perovskite, Ba-substituted LaCoO3, oxide, thermoelectric, p-type semiconductor
In the present work, dense perovskite ceramics were successfully prepared from a series of La1−xBaxCoO3 solid solutions in the range of substitution 0 ≤ x ≤ 0.75 using solid state reaction and conventional sintering. Structural properties of La1−xBaxCoO3 were systematically investigated and thermoelectric properties were measured in the temperature range of 330-1000 K. The results show that the thermoelectric properties of Ba-substituted LaCoO3 depend on x. Indeed, at 330 K, electrical conductivity presents an optimum value for x = 0.25 with a value of σmax ≈ 2.2×105 S·m-1 whereas the Seebeck coefficient decreases when x and/or the temperature increases. The Ba-substituted LaCoO3 samples exhibit p-type semiconducting behaviour. The best power factor value found is 3.4×10-4 W·m-1·K-2 at 330 K for x = 0.075, which is 10% higher than the optimum value measured in La1-xSrxCoO3 for x = 0.05. The thermal diffusivity and thermal conductivity increase with increasing temperature and Ba concentration. La1−xBaxCoO3 shows a maximum figure of merit (ZT = 0.048) for x = 0.05 at 330 K, 25% higher than the best value in La1-xSrxCoO3 compounds.
Tsinghua University Press
Mohamed Ali BOUSNINA, Fabien GIOVANNELLI, Loïc PERRIERE et al. Ba substitution for enhancement of the thermoelectric properties of LaCoO3 ceramics (0≤x≤0.75). Journal of Advanced Ceramics 2019, 8(4): 519-526.