부산대학교 도서관

In this work, we synthesized cubic perovskite ceramics of the whole La1–xSrxCoO3(0 ≤ x≤ 1) solid solution for the first time. Synthesis was carried out by solid state reaction and conventional sintering to reach dense ceramics. For x> 0.8, it was necessary to substitute 3% cobalt by silicon to stabilize the cubic perovskite structure. Electrical conductivity increased with Sr content to reach 3×105S∙m–1at 330 K for x= 0.3. However, the optimum electrical properties have been found for x= 0.05 at 330 K with PFmax= 3.11×10–4W∙m–1∙K–2. Indeed, the Seebeck coefficient was decreasing when xincreased to reach values close to 0 for x≥ 0.3. Thermal conductivity was low at low temperature (≈ 2.5 W∙m–1∙K–1) and increased up to 6.5 W∙m–1∙K–1when temperature increased. As the highest power factor was reached at low temperature as well as the lowest thermal conductivity, La1–xSrxCoO3compounds with low xvalues appeared as very promising thermoelectric materials around room temperature, on the contrary to layered cobalt oxides. For high xvalues, Seebeck coefficient values close to zero made these materials unsuitable for thermoelectric applications.