2010, Vol.20, No.2

Journal of the Korean Crystal Growth and Crystal Technology 2023 KCI Impact Factor : 0.19

pISSN : 1225-1429 / eISSN : 2234-5078
https://journal.kci.go.kr/jkcgct

Sr0.6Ba0.4Nb2O6 (60SBN) and Sr0.75Ba0.35Nb2O6 (75SBN) single crystals were grown by Czochralski method. Growing direction was <001>, and as-grown crystals has well-developed (001) plane. Temperature- and frequency dependence of dielectric constant represent relaxor ferroelectrics. 60SBN has wider optical transmittance than 75SBN.

The microstructural change of the Sm0.5Sr0.5CoO3 (SSC) electrode for a cathode material of solid oxdie fuel cells (SOFCs) deposited by the electrostatic spray deposition (ESD) technique was characterized. Samarium chloride hexahydrate (SmCl3 · 6H2O), strontium chloride hexahydrate (SrCl2 · 6H2O), cobalt nitrate hexahydrate (Co(NO3)2 · 6H2O) as starting materials and methyl alcohol as solvent were used to make precursor solution. The suitable porous SSC films for a cathode of SOFCs were deposited on Si substrate and it is observed that the microstructure was strongly dependent on processing parameters such as deposition time, substrate temperature, and applied voltage. Scanning Electron Microscope (SEM) and X-ray Diffractometer (XRD) measurement were used to investigate the microstructure and crystallinity of the SSC films. The ESD technique is shown to be an efficient method in which the SOFCs’ cathode film can be fabricated with the desired phases and microstructure.

The synthesis and reactivities of molybdenum carbide crystallites were examined in this study. Especially, the effect of synthesis conditions were scrutinized on the preparation of molybdenum carbide crystallites. In order to perform this purpose, various characterization techniques such as BET surface area and oxygen uptake measurements were employed for the synthesized molybdenum carbide crystallites. First of all, the molybdenum carbide crystallites were synthesized using molybdenum oxide crystallites and methane gas or methane-hydrogen mixture. The experimental results showed that BET surface areas ranged from 7.4 m 2/g to 31 m 2/g and oxygen uptake values varied from 8.1 μmol/g to 24.3 μmol/g. The Mo compounds were found to be active for ammonia decomposition reaction. Even though there are some molybdenum carbide crystallites that were exceeded by Pt/Al2O3 crystallite, the steady state reactivities for other molybdenum carbide crystallites were comparable to or even higher than that determined for the Pt/Al2O3 crystallite. These results implied that molybdenum carbide crystallites could be one of the promising crystallites that might be substitutes for Pt-like noble metal crystallites in the petroleum processes.