부산대학교 도서관

Barium strontium cobaltite (Ba0.5Sr0.5CoO3−δ) nanoparticles were synthesized by using without water and surfactant (WOWS) sol-gel method, co-precipitation method and composite mediated hydrothermal method (CMHM). Co-precipitation synthesis was carried out for 0.4 M precursors solutions of strontium nitrate Sr (NO3)2, cobalt nitrate hexahydrate Co (NO3)2·6H2O and barium nitrate Ba (NO3)2 and with the sodium hydroxide NaOH as precipitating agent, sol-gel synthesis was done using ethylene glycol as precipitating agent and the CMHM synthesis was done using sodium hydroxide and Potassium hydroxide (NaOH-KOH) as reactants and precipitating agents at 180 °C for 65 min. Calcination of the synthesized samples was done at 830 °C for 02 hours. Pellets of calcined powder was sintered at 850 °C for 20 minutes. X-ray diffraction (XRD) study was used to find the structural parameters (crystal structure, crystallite size and phase purity). The observed phase transformation of pure barium strontium cobaltite monoclinic to orthorhombic structure was found after heat treatment. Crystallite sizes were calculated by using Scherrer’s formula. Temperature dependent (100 to 600 °C) dc conductivities of the sintered pellets were measured and found to be increased with the successive increase in measuring temperature. Temperature dependent (100 to 600 °C) impedances of all samples synthesized through wet chemical methods at fixed frequency of (10kHz) was also measured and compared. The structural and AC/DC electrical properties were correlated to different synthesis methods. The synthesized samples can be thought as an electrode material for intermediate temperature range solid oxide fuel cells (IT-SOFCs).