Effect of Hot-Defection on Thermoelectric Properties of Ca3Co4O9 Synthesized By Hot Pressing

Abstract

The Calcium Cobalt Oxide (Ca₃Co₄O₉) nano powder were synthesized by a Sol-gel method using calcium nitrates (Ca(NO₃)₂×4H₂O) and cobalt nitrates (Co(NO₃)₂×6H₂O) raw materials. The nano powder was grinded by mortar for 2 h in air and optimized to achieve highly pure and fully dense pellets by hot pressing method at 900°C for 1 h in Ar atmosphere. The sample was annealed by furnace 900 °C for 12 h in air at after hot pressing. The crystal structure of sample was analyzed by X-ray diffraction technique and compared with literature review data. The electrical resistivity, Seebeck coefficient and power factor of the sample were measured and evaluated by ZEM3 at room temperature to 600 °C. It was found that the crystal structure Ca₃Co₄O₉ shows monoclinic structure correspond with literature data, a = 5.31 Ȧ, b = 4.58 Ȧ, c = 11.16 Ȧ and  b = 102.82°. The highest power factor value of Ca₃Co₄O₉ is 0.18 mW m^-1K^-2 at 600°C.