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CA:HP42 The Influence of Metal Impurity Content in Raw Si Powder on the Characteristics of Sintered Reaction Bonded Silicon Nitrides
D. KUSANO, H. HYUGA, Y. ZHOU, K. HIRAO, Fine Ceramics Research Association, AIST Chubu, Nagoya, Japan
Recently Si3N4 has attracted attention as a substrate material for power semiconductor devices because of its excellent mechanical properties and high intrinsic thermal conductivity. Zhou et al. have indicated that a reaction bonding process followed by post-sintering is the sensible approach for fabricating Si3N4 ceramics with both high thermal conductivity and high strength. In their investigation high purity Si powder was employed to exclude the influence of impurity elements. However, from the standpoint of industrial application, it would be of great importance to know what level of metallic impurities in the raw powders is tolerable. Our group has, therefore, started systematic investigations on the effect of metal impurities. In this presentation, the sintered reaction bonded Si3N4 were fabricated using high purity Si powder added with various amounts of iron and aluminum impurities, and the thermal, mechanical and electrical properties of the products were examined to clarify the influence of impurity iron content. Research supported by NEDO, Japan.
CA:HP43 The Effect of the Si3N4 diluent for Sintered Reaction-bonded Silicon Nitride
S. IWAKIRI, Y. ZHOU, H. HYUGA, K. HIRAO, Fine Ceramics Research Association, AIST Chubu, Nagoya, Japan
Recently, it was reported that a reaction bonding process followed by post-sintering is an effective way of fabricating Si3N4 ceramics with both high thermal conductivity and high strength. In this process, Si powder is used as a starting material and Si3N4 is converted from Si through the nitridation reaction of Si. But, it is a so highly exothermic reaction that the reaction heat may cause the melting of the Si compacts and result in deformation and incomplete nitridation during mass production. Therefore our group has started systematic studies on the effective control of the reaction heat by adding Si3N4 as a diluent to Si. In this study, Si3N4 ceramics were prepared from mixtures of Si and Si3N4 through reaction bonding process followed by post-sintering, and the relationship between the characteristic of nitrided compact and characteristic of sintered body was evaluated. Research supported by NEDO, Japan.
CA:HP45 Grinding and Characterisation of Nano Pigments for Inkjet Decoration of Ceramic Tiles
E. KUCUKOGLU1, E. OZEL2, 1Ceramic Research Center, Eskisehir, Turkey; 2Anadolu University, Department of Material Science and Engineering, Eskisehir, Turkey
Inkjet decoration, especially in the past decade, is increasingly spreading as a decoration method in different application fields. In ceramic industry this decoration method has several advantages due to being applied to different patterns, having a shorter setup time in the process of switching, three-dimensional decoration possibility, and less need of pigment and less ink waste. İnkjet inks are suspensions which consist of mostly inorganic pigments or complex metal oxides. İnorganic pigments are preferred due to the fact that have more color stability than the organic ones. Inorganic pigments, used in inks, are prepared at the nanosize to reduce the tendency of wear and clogging in piezo-ceramic nozzles. This study discusses the production of nanosize brown pigments by the grinding method and also optimum grinding parameters that need to be determined.
CA:HP46 Influencing Parameters of Intercalation of Solid Ammonium Acetate into Kaolinite
A. KOVACS, E. MAKÓ, University of Pannonia, Veszprem, Hungary
The intercalation of kaolinites is important for the ceramic, paper, plastic, and pharmaceutical industry especially in the field of advanced nano-composites. A wet homogenization method was applied to prepare the kaolinite–ammonium acetate intercalation complexes. The effectiveness of intercalation and influencing factors were analyzed and evaluated. The results show that the intercalation of kaolinite by solid ammonium acetate strongly depends on crystallinity of kaolinite, amount of intercalating reagent, ammonium acetate/water mass ratio, presence of air, and aging time. The low-defect kaolinite is conducive to intercalate ammonium acetate. A higher amount of intercalating agent increases the degree of intercalation, but 1.5 ammonium acetate/water mass ratio seems to be favorable for intercalation. The wet homogenizing method combined with ageing in closed sample holder proved to be effective to intercalate solid ammonium acetate.
Acknowledgement
The support of the Hungarian Ministry of Culture and Education under grant TÁMOP-4.2.2.A-11/1/ KONV-2012-0071 is gratefully acknowledged. The project is co-financed by the European Social Fund with the support of the European Union.
CB:HP22 Self-assembled α-Fe2O3 Mesocrystals/Graphene Nanohybrid for Enhanced Electrochemical Capacitor
LIAN GAO, SHUHUA YANG, XUEFENG SONG, PENG ZHANG, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
Self-assembled α-Fe2O3 mesocrystals/graphene nanohybrids have been successfully synthesized, which possess a unique mesocrystal porous structure, a large specific surface area, and high conductivity. Mesocrystal structure has recently attracted unparalleled attention due to their promising application in energy storage as electrochemical capacitors. However, mesocrystal/graphene nanohybrids and their grow mechanism have not been clearly investigated. Here we show a facile fabrication of short rod-like α-Fe2O3 mesocrystals/graphene nanohybrids by self-assembly of FeOOH nanorods as the primary building blocks on graphene under hydrothermal conditions, accompanied and promoted by concomitant phase transition from FeOOH to α-Fe2O3. A systematic study of the formation mechanism is also presented. The galvanostatic charge/discharge curve shows a superior specific capacitance of the as-prepared α-Fe2O3 mesocrystals/graphene nanohybrid (considering total mass of active materials), which is 306.9 F g-1 at 3 A g-1 in the aqueous electrolyte under voltage ranges of up to 1 V. The nanohybrid with unique sufficient porous structure and high electrical conductivity allows for effective ion and charge transport in the whole electrode.
CB:HP23 Coacervate-mediated Mineralization of Calcium Carbonate Microparticles for Drug Delivery
V.R. LAUTH, M. MAAS, K. REZWAN, Advanced Ceramics Institute, University of Bremen, Bremen, Germany
Microspheres of calcium carbonate loaded with active agents were synthesized using a bio-inspired mineralization approach. Polyacrilic acid (PAA) is used as the additive to modify mineralization, stabilize amorphous calcium carbonate (ACC) and allow the formation of coacervate droplets. These coacervates are submicron-sized droplets that phase-separate from the aqueous solution due to electrostatic interaction between calcium ions and the negatively charged polymer. The size of the droplets may be tailored by controlling the polyelectrolyte concentration and the reaction time of the complexation. The incorporation of active agents within the coacervate droplets is achieved by dispersing the respective molecules in the aqueous solution prior to phase separation. In order to stop the complexation and to stabilize the loaded-droplets, sodium carbonate is added to the solution leading to mineralization of the complex. Since the reactions take place under aqueous conditions, at mild pH and at room temperature, the process presents effective way to synthesize drug-loaded biocompatible ACC microparticles.
CB:HP24 Facile Synthesis of Nitrogen-doped Graphene-ultrathin MnO2 Sheets Composites and their Electrochemical Performances
XUEFENG SONG, SHUHUA YANG, PENG ZHANG, LIAN GAO, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
Nitrogen-doped graphene-ultrathin MnO2 sheets composites (NGMCs) were prepared through a one step hydrothermal method at low temperature (120 °C). Ultrathin MnO2 sheets were well-dispersed and tightly anchored on graphene sheets, which were doped with nitrogen simultaneously. NGMCs electrode exhibited enhanced capacitive performances relative to those of undoped graphene-ultrathin MnO2 sheets composites (GMCs). As the current density increased from 0.2 to 2 A/g, the capacitance of NGMCs still retained ～74.9%, which was considerablely higher than that of GMCs (27%). Moreover, over 94.2% of the original capacitance was maintained after 2000 cycles, indicating a good cycle stability of NGMCs electrode materials.
CB:HP25 Two-step Synthesis of Ultrafine and Nanosized Powders of Tungsten Oxide
I.V. NIKOLAENKO, G.P. SHVEIKIN, Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
In this work a new method of ultrafine and nanosized powders of tungsten oxide and carbide synthesis by means of combinating carbon carrier supported classic liquid-phase precipitation and low-temperature microwave treatment is presented. The use of carbon additive on the precipitation stage makes the adsorption of tungstic acid particles on the surface of acetylene black possible, and thereby to reduce particle agglomeration and to obtain precursor powder with nanodispersed particles size. As it is generally known, microwave heating is more extreme than traditional method of heating, and this feature also allows to block grain growth of substances produced.
The full range of intermediate substances obtained during thermolysis, reduction and carbidization precursors to final products were presented. The thermolysis of tungstic acid with the formation of tungsten oxide and carbide ultrafine particles of different modifications were studied. It was shown, that cooling ammonium tungstate solution to 4°C , and use of carbon carrier on the precipitation stage can increase specific surface area from 20 to 100 m2/g. With the use of SEM precursors particles size were examined (200 nm) and the morphology of initial, intermediate and final products was shown.
CB:HP26 Fabrication Novel Nanostructural Tungsten Based Composites
A. PEIKRISHVILI, E. CHAGELISHVILI, V. PEIKRISHVILI, M. TSIKLAURI, A. DGEBUADZE, Science and Technology Center in Ukraine, Tbilisi, Georgia
Different precursors of refractory nanostructural W-Ag(Cu) and W-Ta composites were consolidated into cylindrical billets by hot explosive consolidation (HEC) method. Different types of compositions with a nanoscale W and Ta phases(80,100 & 150nm) and coarse matrix phase (Ag, Cu) were consolidated to near theoretical density under and around of melting point of Silver and Copper (950-1000oC). In case of W-Ta the temperature was under 1100 °C.
The intensity of loading in all experiments was around 10 GPa. The combination of high temperatures and two stage explosive densification processes was found to be beneficial to the consolidation of the nanostructural W based composites, resulting in high densities, good integrity, and good electronic properties. The structure and property of the samples depends on the value of consolidation temperature and dimension of consolidated particle sizes. It was established that for the W-Ag based composites application of high temperature and consolidation of precursors near melting point of silver 940 °C gives good result and samples without cracking, high value of density and uniform distribution of consisting phases were obtained.
CB:HP27 Bioactive Materials Manufactured from Natural Calcium Phosphates
A. DOBRADI, M. ENISZ-BODOGH, K. KOVACS, University of Pannonia, Veszprém, Hungary
Constituents of bioactive materials (glasses, ceramics, glass ceramics) are identical to those of human bones: hydroxylcarbonate-apatite, hydroxyl/fluoro-apatite and β-whitlockite. These are made of high purity chemicals, but natural Ca-phosphates obtained by chemical/heat treatment of animal bones can also be used. These natural raw materials contain the most important trace elements of human bones. Main advantage of Ca-phosphate biomaterials is their ability to establish a direct bond to bones, therefore they can be used as a prosthetic bone replacement. Body fluids generate an apatite compound similar to bones on the surface of bio-glasses. Their clinical use is limited by their low mechanical strength. This can easily be improved by producing glass ceramics containing crystalline apatite and wollastonite. Phase changes of heat treated animal bones as well as their influence onto the microstructure and solubility was investigated. Glass ceramics were produced from selected animal bones having advantageous phase compositions. Phase changes of bioactive glass ceramics made of high purity chemicals and grinded bone additives were compared. Effect of heat controlled crystallisation onto the solubility, microstructure, and mechanical properties of biomaterials was evaluated.
CD:HP05 Influencing Factors on the Reactive Wetting of Cu-Sn-Ti- and Ag-Cu-Ti-alloys on Silicon Carbide – Microstructural Observations, Effects and Multivariate Modelling
W. TILLMANN, J. PFEIFFER, L. WOJARSKI, M. BRUNS, Institute of Materials Technology, TU Dortmund, Germany
Despite the fact that active brazing represents a suitable and well-established method for joining ceramics to each other as well to metals, issues concerning possible influences and their effects on the wetting properties of the used filler alloys are not yet entirely clarified. It is well known that process parameters such as the temperature, the surface roughness of the ceramic, and the atmosphere during wetting influence the wetting angle and the spreading kinetics of the molten filler metal. However, a quantitative description of these influences is still missing.
This study closely investigates the isolated effects of the temperature, the surface roughness of the ceramic, as well as the atmosphere on the wetting of Ag-Cu-Ti and Cu-Sn-Ti on silicon carbide. In order to evaluate the effects of the considered factors as well as their interdependencies, a multivariate statistical approach is employed and a linear regression model for both, the contact angle and the spreading area, will be derived. Besides quantitative measurements of the contact angle on solidified sessile drops, microstructural and chemical aspects will be discussed and connected to the results of the wetting experiments as well. By this means, valuable information can be obtained which lead to a profound understanding concerning changes in the wetting behavior. Furthermore, the study allows a comparison of measurements carried out using varying experimental conditions.
CE:HP21 MgAl2O4 ceramic fibres for virus removal from drinking water
M. SCHABIKOWSKI, W.SOJA, D. KATA, T. GRAULE, AGH University of Science and Technology, Cracow, Poland
Viral contamination of drinking water is a growing issue especially in less-developed coun-tries. State of the art organic membranes are of 10÷20 nm pore size. These membranes are prone to clogging and are characterised by high pressure drop during filtration. Due to material used they are also difficult to clean (usually by means of chemical treatment), thus reduc-ing their lifetime. Recent studies have shown that viruses can be efficiently removed by adsorption-enhanced filtration. This type of filtration relies on electrostatic surface interactions between contaminants and filters. Because of the fact that many viruses are negatively charged in water positively-charged media with large surface area will potentially be a good candidate for removal of viral contamination from drinking water. This work presents a study on fabrication of submicron ceramic fibres with the use of forcespinning. The adsorption principle eliminates the need of small size pores eliminating high pressure drop issue. Fibres are characterised by large surface area and, due to its nature, can be easily purified after operation by thermal treatment, which should increase the lifetime of a final product.
CF:HP14 Stressed Oxidation Life Predication of 3D C/SiC in Static Atmospheres
XINGANG LUAN, LAIFEI CHENG, Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an, Shaanxi, China
For the applications in high temperature aero-engine environments, the stressed oxidation of 3D C/SiC composite was investigated in simulating aero-engine environments. The degradation process of 3D C/SiC was studied, the degradation mechanisms and the effects of atmospheres and loads were discussed. The continuity and periodicity of the degradation process because of the capability of the composite in remembering the damage were found. The degradation mode of divisional load-bearing and divisional damage is suggested for the first time. The divisional area depended not on the kinds of load but on the max value of load history. Oxygen and water vapor were the major factors to induce the degradation of 3D C/SiC, Sodium sulfate vapor accelerated the degradation by facilitating the oxidation of SiC which resulted in the increase of interface strength. The interface strength affected not only the strength and the toughness of the composite, but also the degradation process. When the interface strength was higher than the appropriate value, the strength of 3D C/SiC will be improved because of the slight degradation of interface. The effect of kinds of load on the degradation speed of 3D C/SiC is carried out by changing the number and distribute of cracks.
An uniform stressed oxidation degradation model was established. The life prediction equation was deduced based on the model, in which the parameters included temperature, atmosphere pressure, partial pressure of oxygen, kinds of load, normalization peak strength, properties of fiber, braiding angle of fiber preform and thickness of sample, et al.. It was proved by the experimental results that the prediction accuracy of the proposed equation was good in the researched environments.
CF:HP15 Influence of B4C, SiC and Si3N4 Additions on Microstructures and Selected Properties of Titanium Nitride Matrix Materials obtained by HPHT Method
J. CYBORON, P. KLIMCZYK, P. FIGIEL, M. KAROLUS, The Institute of Advanced Manufacturing Technology, Cracow, Poland
The paper presents the results of the High Pressure and High Temperature (HP-HT) sintering and research of Ultra High Temperature Ceramics (UHTC) composites of titanium nitride matrix. The aim of these studies were to determine the influence of additives on the ceramic phase composition, microstructure and selected properties. Three different kinds of mixtures were prepared. B4C, SiC and Si3N4 in amounts of 8 to 22 wt% were added as additional phases. Composites were sintered under high-pressure high-temperature conditions (HP-HT) using a Bridgman-type apparatus at about 6 GPa. Sintering temperature was within the range of 1450 to 1690 ° C, sintering duration was 60s. Phase composition, microstructure, apparent density, Young's modulus, hardness and fracture toughness KIC (HV) using the Vickers indentation method were examined.
The best properties were obtained for sintered titanium nitride with 22 wt% silicon carbide addition . For this material the relative density is 99%, the Young's modulus 435 GPa, Vickers hardness 18.3 GPa HV1 and fracture toughness 5,5 MPa∙m1/2.
CG:HP02 Optical and Electronic Properties of Two-dimensional Ti3C2 Epitaxial Thin Films
J. HALIM1,2,3, M.R. LUKATSKAYA1,2, K.M. COOK1,2, JUN LU3, C.R. SMITH1,2, L.-A. NÄSLUND3, S.J. MAY1, L. HULTMAN3, Y. GOGOTSI1,2, P. EKLUND3, M.W. BARSOUM1, 1Dept. of Materials Science & Engineering, Drexel University, Philadelphia, PA, USA; 2A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, PA, USA, Dept. of Materials Science & Engineering, Drexel University, Philadelphia, PA, USA; 3Thin Film Physics Division, Dept. of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, Sweden
Since the discovery of graphene, two-dimensional (2D) materials receive growing interest because of their unique properties as compared to their bulk counterparts. Although graphene has garnered the lion’s share of this attention, other 2D materials beyond MoS2 and BN are being sought out. Recently, a new family of 2D materials of early transition metal carbides and carbonitrides (Ti2C, Ti3C2, Ti3CN, V2C, Nb2C, Ta4C3 and more) known as MXenes has been discovered. Herein we show the fabrication of a 2D epitaxial Ti3C2 thin film, formed by the selective etching of Al from magnetron sputter-grown Ti3AlC2. The optical transmittance, electrical resistivity, and magnetoresistance of the films were also measured. These data show that the films are up to ~ 90% transparent in the visible to infrared range, and that metallic-like conductive behavior is exhibited down to ~ 100 K. At temperatures below 100 K, resistivity of the films increased with decreasing temperature and magnetoresistance proved to be negative, due to a weak localization phenomenon characteristic of 2D films. These results illustrate the potential for the use of Ti3C2 thin films as transparent conductive electrodes, as well as in electrical, photonic and sensing applications.
1. Department of Materials Science & Engineering, Drexel University, Philadelphia, PA 19104, USA
2. A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, PA 19104, USA. Department of Materials Science & Engineering, Drexel University, Philadelphia, PA 19104, USA
3. Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
CH:HP10 Thermal Stability of Nd-added Pt/SiO2 Catalyst for Oxidation of NO to NO2
YONG KWON CHUNG, JUN YOUNG CHO, GWI RANG KIM, JAE HUN HAN, CHAN PARK, Department of Materials Science and Engineering, Seoul National University, Seoul, Rep. of Korea
Pt-based catalysts cannot be used permanently for the diesel after-treatment system because the catalytic activity is decreased due to coarsening of Pt particles at high temperature of the exhaust gas. In this study, to prevent Pt-based catalyst from deactivation, Nd was added to the Pt/SiO2 catalyst, and the effect of the Nd addition on the catalytic activity was investigated. The Pt/SiO2 catalyst showed a high catalytic activity for the oxidation of NO but was severely deactivated after the fast thermal aging process. Pt crystallite size was increased and some Pt particles were buried in the SiO2 pore during the fast thermal aging process, which led to the decrease of catalytic activity. Nd-added Pt/SiO2 catalyst showed lower activity than Pt/SiO2 catalyst, but Pt-Nd/SiO2 catalyst maintained its catalytic activity after fast thermal aging process. The stable Nd silicate, on which Pt particle is placed, protected the destruction of SiO2 pore, and so the number of the catalytically active site was maintained. Nd was also doped in the Pt site, which brought synergistic effect on oxidation of NO.
CH:HP11 Mechanical and Durable Properties of Ni-YSZ Electrode under High Temperature for Solid Oxide Electrolysis Stack
BYUNG-KOOG JANG1, T. MATSUDAIRA2, S. KITAOKA2, SUNG-DONG KIM3, SANG-KUK WOO3, 1National Institute for Materials Science, Japan; 2Japan Fine Ceramics Center, Japan; 3Korea Institute of Energy Research, Korea
Many researches based on SOFC development and high temperature electrolysis (HTE) have been reported in the last couple of decades. The processing and structure of HTE is closely related to the knowledge and concept of solid oxide fuel cells (SOFCs). Specially, it is very important to evaluate the durability’s properties of oxide electrolysis stacks under high temperature as well as steam environment to apply HTE. Unfortunately, no study has been reported the durable properties of oxide electrolysis stacks at high temperature as well as steam environment. For the reason, the aim of this work is to realize the durable properties (ex, high temperature strength fatigue and creep) at high temperature of 600°C~850°C for oxide electrolysis stacks which consists of 55%NiO-45%YSZ(8mol%Y2O3) composition. NiO-YSZ cathode supports were prepared in the shape of flat tubes by extrusion method. The pre-sintered NiO-YSZ flat tubes were dip-coated in YSZ slurry to secure the interconnector area with a masking fluid and then were sintered at 1400°C for 3h. The creep properties showed decreasing tendency with increasing applied load in range of 40~80MPa and temperature in range of 600°C~800°C. The life time of fatigue at 850°C under Ar-4%H2O environment was decreased with increasing applied load.
CH:HP12 Co-assembly and One-pot Synthesis of Functionalized Mesoporous Silicas with the Use of Polyethyleneimines
A. PAPAVASILIOU, E.G. DEZE, S.K. PAPAGEORGIOU, F.K. KATSAROS, Demokritos National Centre for Scientific Research, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, Athens, Greece; J.L. NYALOSASO, P. COOL, University of Antwerp, Department of Chemistry, Antwerpen, Belgium
Over the last years, mesoporous silicas have gathered immense interest especially in the field of catalysis, considered as excellent catalytic supports owing to their high internal surface area and large mesochannels. Herein, the synthesis of copper functionalized mesoporous silicas by means of co-assembly and one-pot pathways is described. Metal functionalization of the mesostructured material is accomplished with the use of hyperbranched Polyethyleneimines (PEIs), serving both as chelating and secondary structure directing agents. In co-assembly methodology, PEI is introduced into the initial reaction mixture, containing the triblock copolymer Pluronic P123 as the template and TEOS as the silica source. Functionalization of the co-assembled materials is performed at a second step by impregnation into copper nitrate solutions. In one-pot approach, silica’s functionalization is realized in a single step through the direct incorporation of PEI preloaded with copper, into the synthetic gel. Several parameters are investigated including solution’s pH, reaction path, PEI’s content and molecular weight. The effect of hyperbranched polymer on the formation of silica’s mesostructure along with final copper uptake was determined via XRD, N2 porosimetry, SEM and UV-DR analyses.
CI:HP14 APCVD Synthesis of Ti-doped Hematite Photoanode based on Ferrocene Evaporation
SHIPU LI, PENG ZHANG, XUEFENG SONG, LIAN GAO, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
Ti-doped α-Fe2O3 photoanode was prepared by a facile atmospheric pressure chemical vapor deposition (APCVD) method. Evaporation of ferrocene on Ti substrate leads to doping of Ti4+ into hematite thin films. The surface feature shows faceted nanoparticles with sizes of ~30 nm. The photocurrent of this Ti:Fe2O3 in1 M NaOH reaches 110 μA/cm2 at 1.0 VSCE under 9 mW/cm2 illumination. The measured Incident Photon-to-current Conversion Efficiency (IPCE) at 360 nm at 1.0 VSCE is 15.4%. X-Ray photoelectron spectroscopy revealed the Ti atomic concentration of 0.36% in hematite thin film.
CI:HP15 Synthesis and Gas Sensing Properties of TiO2-ZnO Core-Shell Nanowires
JUN-SEONG LEE, SUN-WOO CHOI, AKASH KATOCHI, JAE-HUN KIM, SANG SUB KIM, Department of Materials Science and Engineering, Inha University, Incheon, Rep. of Korea
In recent years, one-dimensional oxide gas sensors have been received much attention for various applications with growth of nano-material industry. Specially, their sensing capability to detect chemical species as low as ppb level is promising due to their peculiar properties such as a large surface-to-volume ratio and nearly perfect crystalline quality. Many efforts have been made for improving the gas detection capability of oxide-nanowire sensors. They include functionalization of noble metallic nanoparticles, doping, composite and the use of core-shell structures. Among them, the core-shell structures are of great importance because of their outstanding capability to detect reducing gases. Formation of a surface-depleted shell layer and heterojunction are responsible for the improved sensing properties. Importantly, the selection of a good material combination is another essential parameter to maximize their sensing capability. In this work, we fabricated TiO2-ZnO core-shell nanowires, where TiO2 nanowires were grown as the core and ZnO as the shell. Their gas sensing properties are tested as a function of ZnO shell layer thickness. We find that the shell layer thickness greatly influences the sensing properties. The underlying sensing mechanism will be discussed in detail.
CI:HP16 Synthesis of CuO-TiO2 Core-shell Nanowires and their Sensing Properties
JAE HYOUNG LEE, SUN-WOO CHOI, AKASH KATOCH, GUN-JU SUN, SANG SUB KIM, Department of Materials Science and Engineering, Inha University, Incheon, Rep. of Korea
Over the past few years, detection of toxic gases has become important for environment and safety applications. A lot of research has been made to realize highly sensitive and selective gas sensors. One approach to improve sensing properties is to use nanostructured materials such as, nanowires, nanofibers and nanorods because they provide a large surface to interact with gas molecules in comparison to bulk or thin film counterparts. In recent years, much effort has been paid to improve their sensitivity by modification of nanostrucutres. Therefore, it is essential to investigate the potential of p-n type core-shell structure in order to realize its applications to gas sensors. In this study, we have fabricated CuO-TiO2 core-shell nanowires. Here, CuO nanowires were synthesized by the thermal oxidation technique at 500 °C in air. Subsequently, TiO2 shell layers were deposited using the atomic layer deposition (ALD) process. The prepared samples were heat-treated at 600 °C for 1 h in air. We investigated their sensing properties to oxidizing and reducing gases as a function of shell layer thickness. We found that the shell thickness is a key processing parameter to improve the sensing performances.The underlying sensing mechanism will be proposed.
CI:HP17 Reactive Chemical Vapor Deposition of (111)-oriented TixAl1-xN Thin Films on Monocrystalline Aluminium Nitride
H. SHIMODA1, 2, F. MERCIER1, S. LAY1, E. BLANQUET1, 1SIMaP, CNRS, Grenoble University, Saint Martin d’Heres, France; 2Tohoku University, Sendai, Japan
In this work, we report on the preparation of Ti1-xAlxN thin films by a novel way, namely Reactive Chemical Vapor Deposition (R-CVD). Recently we have grown Ti1-xAlxN films by R-CVD from reaction of titanium tetrachloride and hydrogen gas mixture on c-plane (0001) monocrystalline hexagonal aluminium nitride layers at varied temperature between 800°C and 1200°C [1]. The Ti1-xAlxN thin films have been analyzed by Field Emission Gun Scanning Electron Microscopy (FEG-SEM), Transmitting Electron Microscope (TEM), and X-ray Diffraction (XRD). Additionally, thermodynamic simulations have been carried out to predict the influence of the major operating parameters. In this presentation, we focus on the chemical processes between the Ti1-xAlxN solid phase and the chlorine-based gaseous phase. The effect of the process conditions such as temperature, composition of the gas phase, deposition time on the thin films’ properties (composition, thickness) will be discussed regarding both experiments and thermodynamic calculations. As a typical result, 70-nm-thick layer with (111)-oriented cubic Ti1-xAlxN (0.1≤x≤0.45) has been obtained. Work is going on to propose the best conditions for preparing Ti1-xAlxN thin films by Reactive CVD.
[1]: R. Boichot et al. SCT, 2013,p118.
CI:HP18 High Temperature Thick Film Resistors for SiC Power Module Applications
T. SHIMIZU, K. TANAKA, Fine Ceramics Research Association (FCRA), KOA Corporation, K. SHINODA, T. TSUCHIYA, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan; Y. NAKAMURA, M. MIYAYAMA, University of Tokyo, Japan
Realization of low carbon-emission society requires silicon carbide (SiC) technology as a post silicon device because it can improve the efficiency of power devices drastically and can also downsize the power modules. The SiC power modules are designed to work at operating temperatures around 250 ℃. Among the peripheral components in SiC power modules, resistors need to withstand higher temperatures because of Joule self-heating, which are expected to be 350 ˚C. However, the use of resin protective coatings and tin-plating electrodes in current resistors limits their use in such high temperatures. Therefore, in order to develop high temperature resistant chip resistors, we have investigated the effect of the protective layer and electrodes on the heat resistance in the chip resistors. The use of the glass protective layer and Au electrodes suppressed the resistance variation less than 0.02% for 1000 h at 250 ℃. On the other hand, at 350 ℃, resistance was dramatically changed after 750 h. Thermal degradation mechanism of the chip resistors is discussed. A part of this research work was carried out under the novel semiconductor power electronics projects realizing low carbon-emission society promoted by New Energy and Industrial Technology Development Organization (NEDO), Japan.
CJ:HP20 The Effect of Barium Carbonate Morphology on the Properties of Barium Titanate
S. CAN1, G.O. DEMIREL2, A.M. AVCI2, E. SUVACI1, E. OZEL1, 1Anadolu University, Department of Materials Science and Engineering, Iki Eylul Campus, Eskisehir, Turkey; 2ENTEKNO Ltd., Anadolu Teknopark, Eskisehir, Turkey
Barium titanate (BaTiO3) is a ferroelectric material, which widely used in electronic systems such as multilayer ceramic capacitors (MLCC), embedded capacitance in printed circuit boards, underwater transducers (sonars) and thermistors with a positive temperature coefficient of resistivity (PTCR) applications. Barium titanate is a very important material for MLCC applications due to its superior frequency character, higher reliability and high dielectric constant. Many methods have been utilized to produce fine BaTiO3 particles including using solid-state reaction, hydrothermal synthesis, solvothermal method, oxalate route etc. Owing to large-scale production option and low cost, solid state reaction is a convenient way for the commercial production of BaTiO3 powders. In the solid-state reaction, BaTiO3 powders are synthesized by mixing the starting materials, usually titanium dioxide (TiO2) and barium carbonate (BaCO3), and calcining them at an elevated temperature. The research objectives of this study were to investigate the effect of the morphology of BaCO3 powder on the physical properties and tetragonality (=c/a) of BaTiO3 powders. Two different BaCO3 powders which have needle like and equiaxied shape were used to produce BaTiO3 powders via solid-state reaction. With using equiaxied BaCO3, tetragonality of BaTiO3 powder was 1.006 with particle size > 350 nm. On the other hand, higher tetragonality (1.0084) with particle size < 350 nm was obtained with using needle like BaCO3, under the same conditions.
CJ:HP21 Effects of Hydrothermally Synthesized Powder Properties on Electrical and Optical Properties of Magnetron Sputtered
(SnO2)x(ZnO)1-x (x=0.0-0.5) Thin Films
I.G. TUNCOLU1, C. ACIKSARI1, E. SUVACI1, E. OZEL1, S.I. REMBEZA2, E.S. REMBEZA2, E.YU. PLOTNIKOVA2, N.N. KOSHELEVA2, 1Anadolu University, Dept. of Materials Science and Engineering, Iki Eylul Campus, Eskisehir, Turkey; 2Voronezh State Technical University, Department of Semiconductor Electronics and Nanoelectronics, Voronezh, Russia
Zinc oxide (ZnO) is an n-type semiconductor oxide material which has large band gap (3.37 eV) energy, excellent thermal, chemical and structural properties and using a wide range of applications such as sensors, varistors, cosmetics, transparent conductive electrodes etc. As a transparent conductive oxide (TCO) electrode applications have a number of requirements which can be fulfilled by ZnO. Some of these requirements are high transparency in the visible and near infrared spectral region, and possibility to prepare highly-doped films with high free electron density and relatively low resistivity. Moreover they should be low material costs, nontoxicity, and abundance in earth crust. They have possibility to prepare the TCO layers on large areas (>1m2) by deposition methods like magnetron sputtering. Transparent conducting materials are currently available in the marketplace such as indium tin oxide (ITO). However, due in part to the rising cost and limited availability, there is a high demand towards the development of cheaper more accessible film materials such as doped SnO2. The research objectives of this study were to understand effect of hydrothermally synthesized target properties on physical and electrical properties of magnetron sputtered (SnO2)x(ZnO)1-x (x=0.0-0.5) thin films for transparent conductive electrode applications. ZnO and SnO2 powders were successfully synthesized with hydrothermal synthesis. ZnO powders were synthesized from the hydrous zinc nitrate (Zn(NO3)4.6H2O) with ammonium hydroxide (NH4OH) at pH 8.4 by hydrothermal synthesis at 100°C, 3 hours while SnO2 powders were synthesized at 200°C from hydrous tin oxide, which was prepared by direct strike precipitation of SnCl4 solution by adding NH4OH solution at pH 9. ZnO and SnO2 powders uniaxially pressed with 12x100x4 mm dimensions and sintered 2 hours at 1100°C and 1200°C, respectively. All thin film samples were prepared by ion-beam AC-sputtering in the ambient of argon. The distance between target and substrate was 60 mm, sputtering time on the glass substrate was 300 min. Targets were annealed at 500 °C during 16 hours. The results of optical transmission (transparency) T spectra analysis showed that the transparency of thin films increase with increasing Zn content in SnO2 and ZTO films have maximum transparency with compositional value of 13,78%Sn, 28,66%Zn and 54,18%O at.
CJ:HP22 Effects of Hydrothermally Synthesized Targets Properties on Physical and Electrical Properties of Magnetron Sputtered
(SnO2)X(ZnO)1-x (x = 0.5-1.0) Films for Gas Sensor Application
C. ACIKSARI1, I.G. TUNCOLU1, E. SUVACI1, E. OZEL1, S.I. REMBEZA2, E.S. REMBEZA2, E.YU. PLOTNIKOVA2, N.N. KOSHELEVA2, 1Anadolu University, Dept. of Materials Science and Engineering, Iki Eylul Campus, Eskisehir, Turkey; 2Voronezh State Technical University, Department of Semiconductor Electronics and Nanoelectronics, Voronezh, Russia
Tin oxide (SnO2) is an important electronic material which has been widely used in an extensive range of applications such as gas sensor, catalyst, heat mirror, varistor, transparent thin film electrode, optoelectronic device etc. In gas sensor applications, SnO2-based systems are most promising materials which are capable of sensing a large number of pollution species, offer high sensitivity, simpler design, and relatively inexpensive components. One of the most important factors affecting sensitivity of the sensors is the actual grain or crystallite size that should be less than 10 nm for the sensor materials. The other important property of gas sensor materials is high purity (i.e., > 99.9%). The research objective of the study was to develop a fundamental understanding about formation of thin or thick films by magnetron sputtering technique from the hydrothermally synthesized SnO2 and ZnO targets to achieve high gas sensing characteristics. In this study, ZnO and SnO2 powders were successfully synthesized by hydrothermal method. ZnO powders were synthesized from the zinc nitrate Zn(NO3)2 solution at pH 8.4 by hydrothermal synthesis at 100°C for 3 hour while SnO2 powders were synthesized at 200°C for 24 h from hydrous tin oxide, which was prepared by direct strike precipitation of SnCl4 solution by adding NH4OH solution at pH 9. Average primary particle size of agglomerated SnO2 powder calculated from TEM image was about 3 nm and surface area from the BET analysis was 163 m2/g,. Purity level of synthesized SnO2 powder was 99.97% in. On the other hand, average particle size of ZnO powder from SEM image was about 8-10 µm in length and purity level of ZnO powder was 99.97% in. To produce targets, ZnO and SnO2 powders were uniaxially pressed with 84x10x3 mm dimensions and sintered 2 hours at 1100°C and 1200°C, respectively. Then, the films with different compositions (SnO2)x(ZnO)1-x (x=0.5-1.0) were prepared from SnO2 and ZnO targets by ion-beam ac-sputtering in the ambient of argon. Distance between targets and glass substrate was 60 mm during 5 hours. Prepared films were annealed at 500°C during 16 hours. Elemental composition of the films for different x values was determined by x-ray microanalysis technique. The electrical properties of the films were obtained with the help of Hall effect by Van-der-Pauw method in magnetic field B = 0,63 Tl at room temperature. Gas sensitivities of the films, calculated from the ratio Sg = Rair/Rgas, was measured in the ambient of ethanol with concentration 3000 ppm. Thickness of the sputtered films was about 3-4 μm and average grain size was about 20-25 nm from AFM images. Maximum gas sensitivity of the films was obtained with compositional value of 0.7 Zn % at., 20.8 Sn % at., 78.2 O % at. and this film had maximum gas sensitivity at 200°C.
CL:HP17 Synthesis of Dual Fluorescently Labeled Silica Nanoparticles via a Reverse Microemulsion Method for in Vitro Studies
S. SHAHABI, L. TRECCANI, K. REZWAN, Advanced Ceramics, University of Bremen, Bremen, Germany
For nanotoxicological studies fluorescence nanoparticles (NPs) are an essential tool for NP localization within the cells. However, in many in vitro investigations a clear and non-ambiguous discrimination between NPs and fluorescent stained cellular components is still difficult. To address this challenging task, we show a straightforward method for obtaining dual fluorescently labeled silica NPs with high fluorescence intensity (FI), well-defined surface chemistry, shape and size.
Dual fluorescent SiO2-NPs (DF-NPs) were obtained by a novel, reverse microemulsion method and organic fluorescent dyes were simultaneously entrapped inside core and shell of silica NPs. DF-NPs with controllable shape, sizes from 50 to 60 nm, narrow size distribution and high fluorescent intensity were obtained. Moreover, DF-NPs were found to be highly stable in aqueous and cell culture media over long time-periods under physiological conditions. In vitro studies with bone cells showed that DF-NPs were localizable with high accuracy and clearly distinguishable from fluorescently stained cell components. Due to its versatility, our approach enables the synthesis of well-defined NPs highly suitable for toxicological screening, imaging and biomedical investigations and for elucidating NP-cell interactions.
CL:HP18 Huge Susceptibility Increase within the (1-x) TeO2 + x TeO3 Crystal System: Ab Initio Calculation Study
A. PLAT, M. COLAS, J. CORNETTE, M.B. SMIRNOV, O. NOGUERA, O. MASSON, A.P. MIRGORODSKY, P. THOMAS, Université de Limoges, Laboratoire de Sciences des procédés céramiques et traitements de surface (SPCTS), Limoges, France
TeIVO2-based materials and especially glasses have extraordinary dielectric characteristics and therefore are of a great interest for non-linear optical applications as they have shown non-linear optical susceptibilities, χ(3), 50 times greater than that of silica. In this connection, many studies are devoted to the influence of modifiers on the TeO2-MiOk glass constitution and properties and a special attention is paid to the MiOk modifiers in which cations are the d-elements with valence 6. The aim of this work is to estimate such optical characteristics for a quite particular modifier, namely, for the case M = TeVI. In a first step we investigated by using ab initio calculation the non-linear optical properties of the crystalline phases within the TeO2-TeO3 system, TeO2, Te4O9, Te2O5 and TeO3. We evidenced that the average susceptibility χ(3) increases up to 10 times with increasing TeVI content. This augmentation can be related to structural changes associated to a decreasing of the optical band gap and a polymerization of the tellurium-oxygen network (strong augmentation of the Te-atom d-function contributions in valence molecular orbitals which accompanies the Te4+-Te6+ transformation).
CM:HP06 Strength Optimization of Geopolymers Containing Blast Furnace Slags as Sole Binder
I. BALCZAR, T. KORIM, K. KOVÁCS, University of Pannonia, Veszprém, Hungary
Industrial waste (e.g. fly ash and granulated blast furnace slag) based alkali-activated cements play an increasing role as a successful substitute of ordinary Portland cements due to their superior durability and environment friendliness.
Research has been focused onto the manufacture of a novel waste-based binding material system having adequate strength. The molar ratio of components was optimized to reach this favourable property. Granulated blast furnace slag from Dunaújváros Steel Plant was applied as basic raw material. Activating solution was obtained from sodium hydroxide and sodium silicate mixtures, and standard sand was added to the viscous geopolymer paste. Compressive strength, bulk density, and relation of physical properties to phase composition and morphology were studied and evaluated.
Two set of samples were prepared, and the SiO2/Al2O3 as well as the Na2O/Al2O3 molar ratio were varied over a wide range. As a result, compressive strength of blast furnace slag based samples (45.5 MPa and 47.3 MPa at 7 and 28 days age, respectively) surpassed the 28 day compressive strength of Class 2 Portland cements (42.5 MPa).
CN:HP16 Preparation of a SiO2-Na2O-CaO-B2O3-CuO Frite with Photocatalytic Properties for Possible Application In Self-cleaning Ceramic Glaze
J.E. HERNÁNDEZ MOTA1, J.J. RUIZ VALDÉS1, A. HERNÁNDEZ RAMÍREZ2, 1Laboratorio de Materiales III, Escuela de Posgrado, Facultad de Ciencias Químicas, UANL, Monterrey, Nuevo León, México, 2Laboratorio de Fotocatálisis y Electroquímica Ambiental, Escuela de Posgrado, Facultad de Ciencias Químicas, UANL, Monterrey, Nuevo León, México
In the actual production of ceramic materials such as tiles and pavements there is a great interest in the development of self-cleaning ceramic surfaces, wich can be obtained by specific surface treatments or by using coatings or glazes which could exhibit this property. In the present investigation, CuO (Eg=1.4) is used as a semiconductor material in the preparation of a ceramic frit by fusion-casting method, incorporating different concentrations of CuO in the SiO2-Na2O-CaO-B2O3 vitreous system, in order to present photocatalytic activity within the frit an to obtain a glaze which could be capable of degrading organic compounds, and its application on a ceramic substrate. The frits were characterized by XRD, DTA and XPS. Through Diffuse Reflectance Spectroscopy, the bandgap (Eg) of the material was calculated; photocatalytic activity of the frit powders were determined by degradation reactions of methylene blue dye. The results showed that obtained frits presented Tg values between 600 and 700°C. The Eg value of the frit without CuO was 4.17eV and decreased to a value of 2.43eV as concentration of CuO increased. As expected, frits with higher CuO concentration degraded more effectively the organic dye, becomming a promising perspective for photocatalytic coating purposes.
D. KUSANO, H. HYUGA, Y. ZHOU, K. HIRAO, Fine Ceramics Research Association, AIST Chubu, Nagoya, Japan
Recently Si3N4 has attracted attention as a substrate material for power semiconductor devices because of its excellent mechanical properties and high intrinsic thermal conductivity. Zhou et al. have indicated that a reaction bonding process followed by post-sintering is the sensible approach for fabricating Si3N4 ceramics with both high thermal conductivity and high strength. In their investigation high purity Si powder was employed to exclude the influence of impurity elements. However, from the standpoint of industrial application, it would be of great importance to know what level of metallic impurities in the raw powders is tolerable. Our group has, therefore, started systematic investigations on the effect of metal impurities. In this presentation, the sintered reaction bonded Si3N4 were fabricated using high purity Si powder added with various amounts of iron and aluminum impurities, and the thermal, mechanical and electrical properties of the products were examined to clarify the influence of impurity iron content. Research supported by NEDO, Japan.
CA:HP43 The Effect of the Si3N4 diluent for Sintered Reaction-bonded Silicon Nitride
S. IWAKIRI, Y. ZHOU, H. HYUGA, K. HIRAO, Fine Ceramics Research Association, AIST Chubu, Nagoya, Japan
Recently, it was reported that a reaction bonding process followed by post-sintering is an effective way of fabricating Si3N4 ceramics with both high thermal conductivity and high strength. In this process, Si powder is used as a starting material and Si3N4 is converted from Si through the nitridation reaction of Si. But, it is a so highly exothermic reaction that the reaction heat may cause the melting of the Si compacts and result in deformation and incomplete nitridation during mass production. Therefore our group has started systematic studies on the effective control of the reaction heat by adding Si3N4 as a diluent to Si. In this study, Si3N4 ceramics were prepared from mixtures of Si and Si3N4 through reaction bonding process followed by post-sintering, and the relationship between the characteristic of nitrided compact and characteristic of sintered body was evaluated. Research supported by NEDO, Japan.
CA:HP45 Grinding and Characterisation of Nano Pigments for Inkjet Decoration of Ceramic Tiles
E. KUCUKOGLU1, E. OZEL2, 1Ceramic Research Center, Eskisehir, Turkey; 2Anadolu University, Department of Material Science and Engineering, Eskisehir, Turkey
Inkjet decoration, especially in the past decade, is increasingly spreading as a decoration method in different application fields. In ceramic industry this decoration method has several advantages due to being applied to different patterns, having a shorter setup time in the process of switching, three-dimensional decoration possibility, and less need of pigment and less ink waste. İnkjet inks are suspensions which consist of mostly inorganic pigments or complex metal oxides. İnorganic pigments are preferred due to the fact that have more color stability than the organic ones. Inorganic pigments, used in inks, are prepared at the nanosize to reduce the tendency of wear and clogging in piezo-ceramic nozzles. This study discusses the production of nanosize brown pigments by the grinding method and also optimum grinding parameters that need to be determined.
CA:HP46 Influencing Parameters of Intercalation of Solid Ammonium Acetate into Kaolinite
A. KOVACS, E. MAKÓ, University of Pannonia, Veszprem, Hungary
The intercalation of kaolinites is important for the ceramic, paper, plastic, and pharmaceutical industry especially in the field of advanced nano-composites. A wet homogenization method was applied to prepare the kaolinite–ammonium acetate intercalation complexes. The effectiveness of intercalation and influencing factors were analyzed and evaluated. The results show that the intercalation of kaolinite by solid ammonium acetate strongly depends on crystallinity of kaolinite, amount of intercalating reagent, ammonium acetate/water mass ratio, presence of air, and aging time. The low-defect kaolinite is conducive to intercalate ammonium acetate. A higher amount of intercalating agent increases the degree of intercalation, but 1.5 ammonium acetate/water mass ratio seems to be favorable for intercalation. The wet homogenizing method combined with ageing in closed sample holder proved to be effective to intercalate solid ammonium acetate.
Acknowledgement
The support of the Hungarian Ministry of Culture and Education under grant TÁMOP-4.2.2.A-11/1/ KONV-2012-0071 is gratefully acknowledged. The project is co-financed by the European Social Fund with the support of the European Union.
CB:HP22 Self-assembled α-Fe2O3 Mesocrystals/Graphene Nanohybrid for Enhanced Electrochemical Capacitor
LIAN GAO, SHUHUA YANG, XUEFENG SONG, PENG ZHANG, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
Self-assembled α-Fe2O3 mesocrystals/graphene nanohybrids have been successfully synthesized, which possess a unique mesocrystal porous structure, a large specific surface area, and high conductivity. Mesocrystal structure has recently attracted unparalleled attention due to their promising application in energy storage as electrochemical capacitors. However, mesocrystal/graphene nanohybrids and their grow mechanism have not been clearly investigated. Here we show a facile fabrication of short rod-like α-Fe2O3 mesocrystals/graphene nanohybrids by self-assembly of FeOOH nanorods as the primary building blocks on graphene under hydrothermal conditions, accompanied and promoted by concomitant phase transition from FeOOH to α-Fe2O3. A systematic study of the formation mechanism is also presented. The galvanostatic charge/discharge curve shows a superior specific capacitance of the as-prepared α-Fe2O3 mesocrystals/graphene nanohybrid (considering total mass of active materials), which is 306.9 F g-1 at 3 A g-1 in the aqueous electrolyte under voltage ranges of up to 1 V. The nanohybrid with unique sufficient porous structure and high electrical conductivity allows for effective ion and charge transport in the whole electrode.
CB:HP23 Coacervate-mediated Mineralization of Calcium Carbonate Microparticles for Drug Delivery
V.R. LAUTH, M. MAAS, K. REZWAN, Advanced Ceramics Institute, University of Bremen, Bremen, Germany
Microspheres of calcium carbonate loaded with active agents were synthesized using a bio-inspired mineralization approach. Polyacrilic acid (PAA) is used as the additive to modify mineralization, stabilize amorphous calcium carbonate (ACC) and allow the formation of coacervate droplets. These coacervates are submicron-sized droplets that phase-separate from the aqueous solution due to electrostatic interaction between calcium ions and the negatively charged polymer. The size of the droplets may be tailored by controlling the polyelectrolyte concentration and the reaction time of the complexation. The incorporation of active agents within the coacervate droplets is achieved by dispersing the respective molecules in the aqueous solution prior to phase separation. In order to stop the complexation and to stabilize the loaded-droplets, sodium carbonate is added to the solution leading to mineralization of the complex. Since the reactions take place under aqueous conditions, at mild pH and at room temperature, the process presents effective way to synthesize drug-loaded biocompatible ACC microparticles.
CB:HP24 Facile Synthesis of Nitrogen-doped Graphene-ultrathin MnO2 Sheets Composites and their Electrochemical Performances
XUEFENG SONG, SHUHUA YANG, PENG ZHANG, LIAN GAO, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
Nitrogen-doped graphene-ultrathin MnO2 sheets composites (NGMCs) were prepared through a one step hydrothermal method at low temperature (120 °C). Ultrathin MnO2 sheets were well-dispersed and tightly anchored on graphene sheets, which were doped with nitrogen simultaneously. NGMCs electrode exhibited enhanced capacitive performances relative to those of undoped graphene-ultrathin MnO2 sheets composites (GMCs). As the current density increased from 0.2 to 2 A/g, the capacitance of NGMCs still retained ～74.9%, which was considerablely higher than that of GMCs (27%). Moreover, over 94.2% of the original capacitance was maintained after 2000 cycles, indicating a good cycle stability of NGMCs electrode materials.
CB:HP25 Two-step Synthesis of Ultrafine and Nanosized Powders of Tungsten Oxide
I.V. NIKOLAENKO, G.P. SHVEIKIN, Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
In this work a new method of ultrafine and nanosized powders of tungsten oxide and carbide synthesis by means of combinating carbon carrier supported classic liquid-phase precipitation and low-temperature microwave treatment is presented. The use of carbon additive on the precipitation stage makes the adsorption of tungstic acid particles on the surface of acetylene black possible, and thereby to reduce particle agglomeration and to obtain precursor powder with nanodispersed particles size. As it is generally known, microwave heating is more extreme than traditional method of heating, and this feature also allows to block grain growth of substances produced.
The full range of intermediate substances obtained during thermolysis, reduction and carbidization precursors to final products were presented. The thermolysis of tungstic acid with the formation of tungsten oxide and carbide ultrafine particles of different modifications were studied. It was shown, that cooling ammonium tungstate solution to 4°C , and use of carbon carrier on the precipitation stage can increase specific surface area from 20 to 100 m2/g. With the use of SEM precursors particles size were examined (200 nm) and the morphology of initial, intermediate and final products was shown.
CB:HP26 Fabrication Novel Nanostructural Tungsten Based Composites
A. PEIKRISHVILI, E. CHAGELISHVILI, V. PEIKRISHVILI, M. TSIKLAURI, A. DGEBUADZE, Science and Technology Center in Ukraine, Tbilisi, Georgia
Different precursors of refractory nanostructural W-Ag(Cu) and W-Ta composites were consolidated into cylindrical billets by hot explosive consolidation (HEC) method. Different types of compositions with a nanoscale W and Ta phases(80,100 & 150nm) and coarse matrix phase (Ag, Cu) were consolidated to near theoretical density under and around of melting point of Silver and Copper (950-1000oC). In case of W-Ta the temperature was under 1100 °C.
The intensity of loading in all experiments was around 10 GPa. The combination of high temperatures and two stage explosive densification processes was found to be beneficial to the consolidation of the nanostructural W based composites, resulting in high densities, good integrity, and good electronic properties. The structure and property of the samples depends on the value of consolidation temperature and dimension of consolidated particle sizes. It was established that for the W-Ag based composites application of high temperature and consolidation of precursors near melting point of silver 940 °C gives good result and samples without cracking, high value of density and uniform distribution of consisting phases were obtained.
CB:HP27 Bioactive Materials Manufactured from Natural Calcium Phosphates
A. DOBRADI, M. ENISZ-BODOGH, K. KOVACS, University of Pannonia, Veszprém, Hungary
Constituents of bioactive materials (glasses, ceramics, glass ceramics) are identical to those of human bones: hydroxylcarbonate-apatite, hydroxyl/fluoro-apatite and β-whitlockite. These are made of high purity chemicals, but natural Ca-phosphates obtained by chemical/heat treatment of animal bones can also be used. These natural raw materials contain the most important trace elements of human bones. Main advantage of Ca-phosphate biomaterials is their ability to establish a direct bond to bones, therefore they can be used as a prosthetic bone replacement. Body fluids generate an apatite compound similar to bones on the surface of bio-glasses. Their clinical use is limited by their low mechanical strength. This can easily be improved by producing glass ceramics containing crystalline apatite and wollastonite. Phase changes of heat treated animal bones as well as their influence onto the microstructure and solubility was investigated. Glass ceramics were produced from selected animal bones having advantageous phase compositions. Phase changes of bioactive glass ceramics made of high purity chemicals and grinded bone additives were compared. Effect of heat controlled crystallisation onto the solubility, microstructure, and mechanical properties of biomaterials was evaluated.
CD:HP05 Influencing Factors on the Reactive Wetting of Cu-Sn-Ti- and Ag-Cu-Ti-alloys on Silicon Carbide – Microstructural Observations, Effects and Multivariate Modelling
W. TILLMANN, J. PFEIFFER, L. WOJARSKI, M. BRUNS, Institute of Materials Technology, TU Dortmund, Germany
Despite the fact that active brazing represents a suitable and well-established method for joining ceramics to each other as well to metals, issues concerning possible influences and their effects on the wetting properties of the used filler alloys are not yet entirely clarified. It is well known that process parameters such as the temperature, the surface roughness of the ceramic, and the atmosphere during wetting influence the wetting angle and the spreading kinetics of the molten filler metal. However, a quantitative description of these influences is still missing.
This study closely investigates the isolated effects of the temperature, the surface roughness of the ceramic, as well as the atmosphere on the wetting of Ag-Cu-Ti and Cu-Sn-Ti on silicon carbide. In order to evaluate the effects of the considered factors as well as their interdependencies, a multivariate statistical approach is employed and a linear regression model for both, the contact angle and the spreading area, will be derived. Besides quantitative measurements of the contact angle on solidified sessile drops, microstructural and chemical aspects will be discussed and connected to the results of the wetting experiments as well. By this means, valuable information can be obtained which lead to a profound understanding concerning changes in the wetting behavior. Furthermore, the study allows a comparison of measurements carried out using varying experimental conditions.
CE:HP21 MgAl2O4 ceramic fibres for virus removal from drinking water
M. SCHABIKOWSKI, W.SOJA, D. KATA, T. GRAULE, AGH University of Science and Technology, Cracow, Poland
Viral contamination of drinking water is a growing issue especially in less-developed coun-tries. State of the art organic membranes are of 10÷20 nm pore size. These membranes are prone to clogging and are characterised by high pressure drop during filtration. Due to material used they are also difficult to clean (usually by means of chemical treatment), thus reduc-ing their lifetime. Recent studies have shown that viruses can be efficiently removed by adsorption-enhanced filtration. This type of filtration relies on electrostatic surface interactions between contaminants and filters. Because of the fact that many viruses are negatively charged in water positively-charged media with large surface area will potentially be a good candidate for removal of viral contamination from drinking water. This work presents a study on fabrication of submicron ceramic fibres with the use of forcespinning. The adsorption principle eliminates the need of small size pores eliminating high pressure drop issue. Fibres are characterised by large surface area and, due to its nature, can be easily purified after operation by thermal treatment, which should increase the lifetime of a final product.
CF:HP14 Stressed Oxidation Life Predication of 3D C/SiC in Static Atmospheres
XINGANG LUAN, LAIFEI CHENG, Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an, Shaanxi, China
For the applications in high temperature aero-engine environments, the stressed oxidation of 3D C/SiC composite was investigated in simulating aero-engine environments. The degradation process of 3D C/SiC was studied, the degradation mechanisms and the effects of atmospheres and loads were discussed. The continuity and periodicity of the degradation process because of the capability of the composite in remembering the damage were found. The degradation mode of divisional load-bearing and divisional damage is suggested for the first time. The divisional area depended not on the kinds of load but on the max value of load history. Oxygen and water vapor were the major factors to induce the degradation of 3D C/SiC, Sodium sulfate vapor accelerated the degradation by facilitating the oxidation of SiC which resulted in the increase of interface strength. The interface strength affected not only the strength and the toughness of the composite, but also the degradation process. When the interface strength was higher than the appropriate value, the strength of 3D C/SiC will be improved because of the slight degradation of interface. The effect of kinds of load on the degradation speed of 3D C/SiC is carried out by changing the number and distribute of cracks.
An uniform stressed oxidation degradation model was established. The life prediction equation was deduced based on the model, in which the parameters included temperature, atmosphere pressure, partial pressure of oxygen, kinds of load, normalization peak strength, properties of fiber, braiding angle of fiber preform and thickness of sample, et al.. It was proved by the experimental results that the prediction accuracy of the proposed equation was good in the researched environments.
CF:HP15 Influence of B4C, SiC and Si3N4 Additions on Microstructures and Selected Properties of Titanium Nitride Matrix Materials obtained by HPHT Method
J. CYBORON, P. KLIMCZYK, P. FIGIEL, M. KAROLUS, The Institute of Advanced Manufacturing Technology, Cracow, Poland
The paper presents the results of the High Pressure and High Temperature (HP-HT) sintering and research of Ultra High Temperature Ceramics (UHTC) composites of titanium nitride matrix. The aim of these studies were to determine the influence of additives on the ceramic phase composition, microstructure and selected properties. Three different kinds of mixtures were prepared. B4C, SiC and Si3N4 in amounts of 8 to 22 wt% were added as additional phases. Composites were sintered under high-pressure high-temperature conditions (HP-HT) using a Bridgman-type apparatus at about 6 GPa. Sintering temperature was within the range of 1450 to 1690 ° C, sintering duration was 60s. Phase composition, microstructure, apparent density, Young's modulus, hardness and fracture toughness KIC (HV) using the Vickers indentation method were examined.
The best properties were obtained for sintered titanium nitride with 22 wt% silicon carbide addition . For this material the relative density is 99%, the Young's modulus 435 GPa, Vickers hardness 18.3 GPa HV1 and fracture toughness 5,5 MPa∙m1/2.
CG:HP02 Optical and Electronic Properties of Two-dimensional Ti3C2 Epitaxial Thin Films
J. HALIM1,2,3, M.R. LUKATSKAYA1,2, K.M. COOK1,2, JUN LU3, C.R. SMITH1,2, L.-A. NÄSLUND3, S.J. MAY1, L. HULTMAN3, Y. GOGOTSI1,2, P. EKLUND3, M.W. BARSOUM1, 1Dept. of Materials Science & Engineering, Drexel University, Philadelphia, PA, USA; 2A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, PA, USA, Dept. of Materials Science & Engineering, Drexel University, Philadelphia, PA, USA; 3Thin Film Physics Division, Dept. of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, Sweden
Since the discovery of graphene, two-dimensional (2D) materials receive growing interest because of their unique properties as compared to their bulk counterparts. Although graphene has garnered the lion’s share of this attention, other 2D materials beyond MoS2 and BN are being sought out. Recently, a new family of 2D materials of early transition metal carbides and carbonitrides (Ti2C, Ti3C2, Ti3CN, V2C, Nb2C, Ta4C3 and more) known as MXenes has been discovered. Herein we show the fabrication of a 2D epitaxial Ti3C2 thin film, formed by the selective etching of Al from magnetron sputter-grown Ti3AlC2. The optical transmittance, electrical resistivity, and magnetoresistance of the films were also measured. These data show that the films are up to ~ 90% transparent in the visible to infrared range, and that metallic-like conductive behavior is exhibited down to ~ 100 K. At temperatures below 100 K, resistivity of the films increased with decreasing temperature and magnetoresistance proved to be negative, due to a weak localization phenomenon characteristic of 2D films. These results illustrate the potential for the use of Ti3C2 thin films as transparent conductive electrodes, as well as in electrical, photonic and sensing applications.
1. Department of Materials Science & Engineering, Drexel University, Philadelphia, PA 19104, USA
2. A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, PA 19104, USA. Department of Materials Science & Engineering, Drexel University, Philadelphia, PA 19104, USA
3. Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
CH:HP10 Thermal Stability of Nd-added Pt/SiO2 Catalyst for Oxidation of NO to NO2
YONG KWON CHUNG, JUN YOUNG CHO, GWI RANG KIM, JAE HUN HAN, CHAN PARK, Department of Materials Science and Engineering, Seoul National University, Seoul, Rep. of Korea
Pt-based catalysts cannot be used permanently for the diesel after-treatment system because the catalytic activity is decreased due to coarsening of Pt particles at high temperature of the exhaust gas. In this study, to prevent Pt-based catalyst from deactivation, Nd was added to the Pt/SiO2 catalyst, and the effect of the Nd addition on the catalytic activity was investigated. The Pt/SiO2 catalyst showed a high catalytic activity for the oxidation of NO but was severely deactivated after the fast thermal aging process. Pt crystallite size was increased and some Pt particles were buried in the SiO2 pore during the fast thermal aging process, which led to the decrease of catalytic activity. Nd-added Pt/SiO2 catalyst showed lower activity than Pt/SiO2 catalyst, but Pt-Nd/SiO2 catalyst maintained its catalytic activity after fast thermal aging process. The stable Nd silicate, on which Pt particle is placed, protected the destruction of SiO2 pore, and so the number of the catalytically active site was maintained. Nd was also doped in the Pt site, which brought synergistic effect on oxidation of NO.
CH:HP11 Mechanical and Durable Properties of Ni-YSZ Electrode under High Temperature for Solid Oxide Electrolysis Stack
BYUNG-KOOG JANG1, T. MATSUDAIRA2, S. KITAOKA2, SUNG-DONG KIM3, SANG-KUK WOO3, 1National Institute for Materials Science, Japan; 2Japan Fine Ceramics Center, Japan; 3Korea Institute of Energy Research, Korea
Many researches based on SOFC development and high temperature electrolysis (HTE) have been reported in the last couple of decades. The processing and structure of HTE is closely related to the knowledge and concept of solid oxide fuel cells (SOFCs). Specially, it is very important to evaluate the durability’s properties of oxide electrolysis stacks under high temperature as well as steam environment to apply HTE. Unfortunately, no study has been reported the durable properties of oxide electrolysis stacks at high temperature as well as steam environment. For the reason, the aim of this work is to realize the durable properties (ex, high temperature strength fatigue and creep) at high temperature of 600°C~850°C for oxide electrolysis stacks which consists of 55%NiO-45%YSZ(8mol%Y2O3) composition. NiO-YSZ cathode supports were prepared in the shape of flat tubes by extrusion method. The pre-sintered NiO-YSZ flat tubes were dip-coated in YSZ slurry to secure the interconnector area with a masking fluid and then were sintered at 1400°C for 3h. The creep properties showed decreasing tendency with increasing applied load in range of 40~80MPa and temperature in range of 600°C~800°C. The life time of fatigue at 850°C under Ar-4%H2O environment was decreased with increasing applied load.
CH:HP12 Co-assembly and One-pot Synthesis of Functionalized Mesoporous Silicas with the Use of Polyethyleneimines
A. PAPAVASILIOU, E.G. DEZE, S.K. PAPAGEORGIOU, F.K. KATSAROS, Demokritos National Centre for Scientific Research, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, Athens, Greece; J.L. NYALOSASO, P. COOL, University of Antwerp, Department of Chemistry, Antwerpen, Belgium
Over the last years, mesoporous silicas have gathered immense interest especially in the field of catalysis, considered as excellent catalytic supports owing to their high internal surface area and large mesochannels. Herein, the synthesis of copper functionalized mesoporous silicas by means of co-assembly and one-pot pathways is described. Metal functionalization of the mesostructured material is accomplished with the use of hyperbranched Polyethyleneimines (PEIs), serving both as chelating and secondary structure directing agents. In co-assembly methodology, PEI is introduced into the initial reaction mixture, containing the triblock copolymer Pluronic P123 as the template and TEOS as the silica source. Functionalization of the co-assembled materials is performed at a second step by impregnation into copper nitrate solutions. In one-pot approach, silica’s functionalization is realized in a single step through the direct incorporation of PEI preloaded with copper, into the synthetic gel. Several parameters are investigated including solution’s pH, reaction path, PEI’s content and molecular weight. The effect of hyperbranched polymer on the formation of silica’s mesostructure along with final copper uptake was determined via XRD, N2 porosimetry, SEM and UV-DR analyses.
CI:HP14 APCVD Synthesis of Ti-doped Hematite Photoanode based on Ferrocene Evaporation
SHIPU LI, PENG ZHANG, XUEFENG SONG, LIAN GAO, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
Ti-doped α-Fe2O3 photoanode was prepared by a facile atmospheric pressure chemical vapor deposition (APCVD) method. Evaporation of ferrocene on Ti substrate leads to doping of Ti4+ into hematite thin films. The surface feature shows faceted nanoparticles with sizes of ~30 nm. The photocurrent of this Ti:Fe2O3 in1 M NaOH reaches 110 μA/cm2 at 1.0 VSCE under 9 mW/cm2 illumination. The measured Incident Photon-to-current Conversion Efficiency (IPCE) at 360 nm at 1.0 VSCE is 15.4%. X-Ray photoelectron spectroscopy revealed the Ti atomic concentration of 0.36% in hematite thin film.
CI:HP15 Synthesis and Gas Sensing Properties of TiO2-ZnO Core-Shell Nanowires
JUN-SEONG LEE, SUN-WOO CHOI, AKASH KATOCHI, JAE-HUN KIM, SANG SUB KIM, Department of Materials Science and Engineering, Inha University, Incheon, Rep. of Korea
In recent years, one-dimensional oxide gas sensors have been received much attention for various applications with growth of nano-material industry. Specially, their sensing capability to detect chemical species as low as ppb level is promising due to their peculiar properties such as a large surface-to-volume ratio and nearly perfect crystalline quality. Many efforts have been made for improving the gas detection capability of oxide-nanowire sensors. They include functionalization of noble metallic nanoparticles, doping, composite and the use of core-shell structures. Among them, the core-shell structures are of great importance because of their outstanding capability to detect reducing gases. Formation of a surface-depleted shell layer and heterojunction are responsible for the improved sensing properties. Importantly, the selection of a good material combination is another essential parameter to maximize their sensing capability. In this work, we fabricated TiO2-ZnO core-shell nanowires, where TiO2 nanowires were grown as the core and ZnO as the shell. Their gas sensing properties are tested as a function of ZnO shell layer thickness. We find that the shell layer thickness greatly influences the sensing properties. The underlying sensing mechanism will be discussed in detail.
CI:HP16 Synthesis of CuO-TiO2 Core-shell Nanowires and their Sensing Properties
JAE HYOUNG LEE, SUN-WOO CHOI, AKASH KATOCH, GUN-JU SUN, SANG SUB KIM, Department of Materials Science and Engineering, Inha University, Incheon, Rep. of Korea
Over the past few years, detection of toxic gases has become important for environment and safety applications. A lot of research has been made to realize highly sensitive and selective gas sensors. One approach to improve sensing properties is to use nanostructured materials such as, nanowires, nanofibers and nanorods because they provide a large surface to interact with gas molecules in comparison to bulk or thin film counterparts. In recent years, much effort has been paid to improve their sensitivity by modification of nanostrucutres. Therefore, it is essential to investigate the potential of p-n type core-shell structure in order to realize its applications to gas sensors. In this study, we have fabricated CuO-TiO2 core-shell nanowires. Here, CuO nanowires were synthesized by the thermal oxidation technique at 500 °C in air. Subsequently, TiO2 shell layers were deposited using the atomic layer deposition (ALD) process. The prepared samples were heat-treated at 600 °C for 1 h in air. We investigated their sensing properties to oxidizing and reducing gases as a function of shell layer thickness. We found that the shell thickness is a key processing parameter to improve the sensing performances.The underlying sensing mechanism will be proposed.
CI:HP17 Reactive Chemical Vapor Deposition of (111)-oriented TixAl1-xN Thin Films on Monocrystalline Aluminium Nitride
H. SHIMODA1, 2, F. MERCIER1, S. LAY1, E. BLANQUET1, 1SIMaP, CNRS, Grenoble University, Saint Martin d’Heres, France; 2Tohoku University, Sendai, Japan
In this work, we report on the preparation of Ti1-xAlxN thin films by a novel way, namely Reactive Chemical Vapor Deposition (R-CVD). Recently we have grown Ti1-xAlxN films by R-CVD from reaction of titanium tetrachloride and hydrogen gas mixture on c-plane (0001) monocrystalline hexagonal aluminium nitride layers at varied temperature between 800°C and 1200°C [1]. The Ti1-xAlxN thin films have been analyzed by Field Emission Gun Scanning Electron Microscopy (FEG-SEM), Transmitting Electron Microscope (TEM), and X-ray Diffraction (XRD). Additionally, thermodynamic simulations have been carried out to predict the influence of the major operating parameters. In this presentation, we focus on the chemical processes between the Ti1-xAlxN solid phase and the chlorine-based gaseous phase. The effect of the process conditions such as temperature, composition of the gas phase, deposition time on the thin films’ properties (composition, thickness) will be discussed regarding both experiments and thermodynamic calculations. As a typical result, 70-nm-thick layer with (111)-oriented cubic Ti1-xAlxN (0.1≤x≤0.45) has been obtained. Work is going on to propose the best conditions for preparing Ti1-xAlxN thin films by Reactive CVD.
[1]: R. Boichot et al. SCT, 2013,p118.
CI:HP18 High Temperature Thick Film Resistors for SiC Power Module Applications
T. SHIMIZU, K. TANAKA, Fine Ceramics Research Association (FCRA), KOA Corporation, K. SHINODA, T. TSUCHIYA, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan; Y. NAKAMURA, M. MIYAYAMA, University of Tokyo, Japan
Realization of low carbon-emission society requires silicon carbide (SiC) technology as a post silicon device because it can improve the efficiency of power devices drastically and can also downsize the power modules. The SiC power modules are designed to work at operating temperatures around 250 ℃. Among the peripheral components in SiC power modules, resistors need to withstand higher temperatures because of Joule self-heating, which are expected to be 350 ˚C. However, the use of resin protective coatings and tin-plating electrodes in current resistors limits their use in such high temperatures. Therefore, in order to develop high temperature resistant chip resistors, we have investigated the effect of the protective layer and electrodes on the heat resistance in the chip resistors. The use of the glass protective layer and Au electrodes suppressed the resistance variation less than 0.02% for 1000 h at 250 ℃. On the other hand, at 350 ℃, resistance was dramatically changed after 750 h. Thermal degradation mechanism of the chip resistors is discussed. A part of this research work was carried out under the novel semiconductor power electronics projects realizing low carbon-emission society promoted by New Energy and Industrial Technology Development Organization (NEDO), Japan.
CJ:HP20 The Effect of Barium Carbonate Morphology on the Properties of Barium Titanate
S. CAN1, G.O. DEMIREL2, A.M. AVCI2, E. SUVACI1, E. OZEL1, 1Anadolu University, Department of Materials Science and Engineering, Iki Eylul Campus, Eskisehir, Turkey; 2ENTEKNO Ltd., Anadolu Teknopark, Eskisehir, Turkey
Barium titanate (BaTiO3) is a ferroelectric material, which widely used in electronic systems such as multilayer ceramic capacitors (MLCC), embedded capacitance in printed circuit boards, underwater transducers (sonars) and thermistors with a positive temperature coefficient of resistivity (PTCR) applications. Barium titanate is a very important material for MLCC applications due to its superior frequency character, higher reliability and high dielectric constant. Many methods have been utilized to produce fine BaTiO3 particles including using solid-state reaction, hydrothermal synthesis, solvothermal method, oxalate route etc. Owing to large-scale production option and low cost, solid state reaction is a convenient way for the commercial production of BaTiO3 powders. In the solid-state reaction, BaTiO3 powders are synthesized by mixing the starting materials, usually titanium dioxide (TiO2) and barium carbonate (BaCO3), and calcining them at an elevated temperature. The research objectives of this study were to investigate the effect of the morphology of BaCO3 powder on the physical properties and tetragonality (=c/a) of BaTiO3 powders. Two different BaCO3 powders which have needle like and equiaxied shape were used to produce BaTiO3 powders via solid-state reaction. With using equiaxied BaCO3, tetragonality of BaTiO3 powder was 1.006 with particle size > 350 nm. On the other hand, higher tetragonality (1.0084) with particle size < 350 nm was obtained with using needle like BaCO3, under the same conditions.
CJ:HP21 Effects of Hydrothermally Synthesized Powder Properties on Electrical and Optical Properties of Magnetron Sputtered
(SnO2)x(ZnO)1-x (x=0.0-0.5) Thin Films
I.G. TUNCOLU1, C. ACIKSARI1, E. SUVACI1, E. OZEL1, S.I. REMBEZA2, E.S. REMBEZA2, E.YU. PLOTNIKOVA2, N.N. KOSHELEVA2, 1Anadolu University, Dept. of Materials Science and Engineering, Iki Eylul Campus, Eskisehir, Turkey; 2Voronezh State Technical University, Department of Semiconductor Electronics and Nanoelectronics, Voronezh, Russia
Zinc oxide (ZnO) is an n-type semiconductor oxide material which has large band gap (3.37 eV) energy, excellent thermal, chemical and structural properties and using a wide range of applications such as sensors, varistors, cosmetics, transparent conductive electrodes etc. As a transparent conductive oxide (TCO) electrode applications have a number of requirements which can be fulfilled by ZnO. Some of these requirements are high transparency in the visible and near infrared spectral region, and possibility to prepare highly-doped films with high free electron density and relatively low resistivity. Moreover they should be low material costs, nontoxicity, and abundance in earth crust. They have possibility to prepare the TCO layers on large areas (>1m2) by deposition methods like magnetron sputtering. Transparent conducting materials are currently available in the marketplace such as indium tin oxide (ITO). However, due in part to the rising cost and limited availability, there is a high demand towards the development of cheaper more accessible film materials such as doped SnO2. The research objectives of this study were to understand effect of hydrothermally synthesized target properties on physical and electrical properties of magnetron sputtered (SnO2)x(ZnO)1-x (x=0.0-0.5) thin films for transparent conductive electrode applications. ZnO and SnO2 powders were successfully synthesized with hydrothermal synthesis. ZnO powders were synthesized from the hydrous zinc nitrate (Zn(NO3)4.6H2O) with ammonium hydroxide (NH4OH) at pH 8.4 by hydrothermal synthesis at 100°C, 3 hours while SnO2 powders were synthesized at 200°C from hydrous tin oxide, which was prepared by direct strike precipitation of SnCl4 solution by adding NH4OH solution at pH 9. ZnO and SnO2 powders uniaxially pressed with 12x100x4 mm dimensions and sintered 2 hours at 1100°C and 1200°C, respectively. All thin film samples were prepared by ion-beam AC-sputtering in the ambient of argon. The distance between target and substrate was 60 mm, sputtering time on the glass substrate was 300 min. Targets were annealed at 500 °C during 16 hours. The results of optical transmission (transparency) T spectra analysis showed that the transparency of thin films increase with increasing Zn content in SnO2 and ZTO films have maximum transparency with compositional value of 13,78%Sn, 28,66%Zn and 54,18%O at.
CJ:HP22 Effects of Hydrothermally Synthesized Targets Properties on Physical and Electrical Properties of Magnetron Sputtered
(SnO2)X(ZnO)1-x (x = 0.5-1.0) Films for Gas Sensor Application
C. ACIKSARI1, I.G. TUNCOLU1, E. SUVACI1, E. OZEL1, S.I. REMBEZA2, E.S. REMBEZA2, E.YU. PLOTNIKOVA2, N.N. KOSHELEVA2, 1Anadolu University, Dept. of Materials Science and Engineering, Iki Eylul Campus, Eskisehir, Turkey; 2Voronezh State Technical University, Department of Semiconductor Electronics and Nanoelectronics, Voronezh, Russia
Tin oxide (SnO2) is an important electronic material which has been widely used in an extensive range of applications such as gas sensor, catalyst, heat mirror, varistor, transparent thin film electrode, optoelectronic device etc. In gas sensor applications, SnO2-based systems are most promising materials which are capable of sensing a large number of pollution species, offer high sensitivity, simpler design, and relatively inexpensive components. One of the most important factors affecting sensitivity of the sensors is the actual grain or crystallite size that should be less than 10 nm for the sensor materials. The other important property of gas sensor materials is high purity (i.e., > 99.9%). The research objective of the study was to develop a fundamental understanding about formation of thin or thick films by magnetron sputtering technique from the hydrothermally synthesized SnO2 and ZnO targets to achieve high gas sensing characteristics. In this study, ZnO and SnO2 powders were successfully synthesized by hydrothermal method. ZnO powders were synthesized from the zinc nitrate Zn(NO3)2 solution at pH 8.4 by hydrothermal synthesis at 100°C for 3 hour while SnO2 powders were synthesized at 200°C for 24 h from hydrous tin oxide, which was prepared by direct strike precipitation of SnCl4 solution by adding NH4OH solution at pH 9. Average primary particle size of agglomerated SnO2 powder calculated from TEM image was about 3 nm and surface area from the BET analysis was 163 m2/g,. Purity level of synthesized SnO2 powder was 99.97% in. On the other hand, average particle size of ZnO powder from SEM image was about 8-10 µm in length and purity level of ZnO powder was 99.97% in. To produce targets, ZnO and SnO2 powders were uniaxially pressed with 84x10x3 mm dimensions and sintered 2 hours at 1100°C and 1200°C, respectively. Then, the films with different compositions (SnO2)x(ZnO)1-x (x=0.5-1.0) were prepared from SnO2 and ZnO targets by ion-beam ac-sputtering in the ambient of argon. Distance between targets and glass substrate was 60 mm during 5 hours. Prepared films were annealed at 500°C during 16 hours. Elemental composition of the films for different x values was determined by x-ray microanalysis technique. The electrical properties of the films were obtained with the help of Hall effect by Van-der-Pauw method in magnetic field B = 0,63 Tl at room temperature. Gas sensitivities of the films, calculated from the ratio Sg = Rair/Rgas, was measured in the ambient of ethanol with concentration 3000 ppm. Thickness of the sputtered films was about 3-4 μm and average grain size was about 20-25 nm from AFM images. Maximum gas sensitivity of the films was obtained with compositional value of 0.7 Zn % at., 20.8 Sn % at., 78.2 O % at. and this film had maximum gas sensitivity at 200°C.
CL:HP17 Synthesis of Dual Fluorescently Labeled Silica Nanoparticles via a Reverse Microemulsion Method for in Vitro Studies
S. SHAHABI, L. TRECCANI, K. REZWAN, Advanced Ceramics, University of Bremen, Bremen, Germany
For nanotoxicological studies fluorescence nanoparticles (NPs) are an essential tool for NP localization within the cells. However, in many in vitro investigations a clear and non-ambiguous discrimination between NPs and fluorescent stained cellular components is still difficult. To address this challenging task, we show a straightforward method for obtaining dual fluorescently labeled silica NPs with high fluorescence intensity (FI), well-defined surface chemistry, shape and size.
Dual fluorescent SiO2-NPs (DF-NPs) were obtained by a novel, reverse microemulsion method and organic fluorescent dyes were simultaneously entrapped inside core and shell of silica NPs. DF-NPs with controllable shape, sizes from 50 to 60 nm, narrow size distribution and high fluorescent intensity were obtained. Moreover, DF-NPs were found to be highly stable in aqueous and cell culture media over long time-periods under physiological conditions. In vitro studies with bone cells showed that DF-NPs were localizable with high accuracy and clearly distinguishable from fluorescently stained cell components. Due to its versatility, our approach enables the synthesis of well-defined NPs highly suitable for toxicological screening, imaging and biomedical investigations and for elucidating NP-cell interactions.
CL:HP18 Huge Susceptibility Increase within the (1-x) TeO2 + x TeO3 Crystal System: Ab Initio Calculation Study
A. PLAT, M. COLAS, J. CORNETTE, M.B. SMIRNOV, O. NOGUERA, O. MASSON, A.P. MIRGORODSKY, P. THOMAS, Université de Limoges, Laboratoire de Sciences des procédés céramiques et traitements de surface (SPCTS), Limoges, France
TeIVO2-based materials and especially glasses have extraordinary dielectric characteristics and therefore are of a great interest for non-linear optical applications as they have shown non-linear optical susceptibilities, χ(3), 50 times greater than that of silica. In this connection, many studies are devoted to the influence of modifiers on the TeO2-MiOk glass constitution and properties and a special attention is paid to the MiOk modifiers in which cations are the d-elements with valence 6. The aim of this work is to estimate such optical characteristics for a quite particular modifier, namely, for the case M = TeVI. In a first step we investigated by using ab initio calculation the non-linear optical properties of the crystalline phases within the TeO2-TeO3 system, TeO2, Te4O9, Te2O5 and TeO3. We evidenced that the average susceptibility χ(3) increases up to 10 times with increasing TeVI content. This augmentation can be related to structural changes associated to a decreasing of the optical band gap and a polymerization of the tellurium-oxygen network (strong augmentation of the Te-atom d-function contributions in valence molecular orbitals which accompanies the Te4+-Te6+ transformation).
CM:HP06 Strength Optimization of Geopolymers Containing Blast Furnace Slags as Sole Binder
I. BALCZAR, T. KORIM, K. KOVÁCS, University of Pannonia, Veszprém, Hungary
Industrial waste (e.g. fly ash and granulated blast furnace slag) based alkali-activated cements play an increasing role as a successful substitute of ordinary Portland cements due to their superior durability and environment friendliness.
Research has been focused onto the manufacture of a novel waste-based binding material system having adequate strength. The molar ratio of components was optimized to reach this favourable property. Granulated blast furnace slag from Dunaújváros Steel Plant was applied as basic raw material. Activating solution was obtained from sodium hydroxide and sodium silicate mixtures, and standard sand was added to the viscous geopolymer paste. Compressive strength, bulk density, and relation of physical properties to phase composition and morphology were studied and evaluated.
Two set of samples were prepared, and the SiO2/Al2O3 as well as the Na2O/Al2O3 molar ratio were varied over a wide range. As a result, compressive strength of blast furnace slag based samples (45.5 MPa and 47.3 MPa at 7 and 28 days age, respectively) surpassed the 28 day compressive strength of Class 2 Portland cements (42.5 MPa).
CN:HP16 Preparation of a SiO2-Na2O-CaO-B2O3-CuO Frite with Photocatalytic Properties for Possible Application In Self-cleaning Ceramic Glaze
J.E. HERNÁNDEZ MOTA1, J.J. RUIZ VALDÉS1, A. HERNÁNDEZ RAMÍREZ2, 1Laboratorio de Materiales III, Escuela de Posgrado, Facultad de Ciencias Químicas, UANL, Monterrey, Nuevo León, México, 2Laboratorio de Fotocatálisis y Electroquímica Ambiental, Escuela de Posgrado, Facultad de Ciencias Químicas, UANL, Monterrey, Nuevo León, México
In the actual production of ceramic materials such as tiles and pavements there is a great interest in the development of self-cleaning ceramic surfaces, wich can be obtained by specific surface treatments or by using coatings or glazes which could exhibit this property. In the present investigation, CuO (Eg=1.4) is used as a semiconductor material in the preparation of a ceramic frit by fusion-casting method, incorporating different concentrations of CuO in the SiO2-Na2O-CaO-B2O3 vitreous system, in order to present photocatalytic activity within the frit an to obtain a glaze which could be capable of degrading organic compounds, and its application on a ceramic substrate. The frits were characterized by XRD, DTA and XPS. Through Diffuse Reflectance Spectroscopy, the bandgap (Eg) of the material was calculated; photocatalytic activity of the frit powders were determined by degradation reactions of methylene blue dye. The results showed that obtained frits presented Tg values between 600 and 700°C. The Eg value of the frit without CuO was 4.17eV and decreased to a value of 2.43eV as concentration of CuO increased. As expected, frits with higher CuO concentration degraded more effectively the organic dye, becomming a promising perspective for photocatalytic coating purposes.