Thermoelectric Properties of Ca3Co2−xMnxO6 (x = 0.05, 0.2, 0.5, 0.75, and 1)

Materials

TemesgenDebelo Desissa¹  Truls Norby¹  Mari-Ann Einarsrud²  SathyaPrakash Singh²  Kjell Wiik²  Nikola Kanas²  Magnus Rotan²  Tor Grande² 

[1] Department of Chemistry, University of Oslo, FERMiO, Gaustadalléen 21, NO-0349 Oslo, Norway;Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway;

关键词: Ca₃Co_2−xMn_xO₆;    thermoelectric properties;    thermal conductivity;    electrical conductivity;    Seebeck coefficient;   

DOI  :  10.3390/ma12030497

来源: DOAJ

【 摘 要 】

High-temperature instability of the Ca₃Co_4−yO_9+δ and CaMnO_3−δ direct p-n junction causing the formation of Ca₃Co_2−xMn_xO₆ has motivated the investigation of the thermoelectric performance of this intermediate phase. Here, the thermoelectric properties comprising Seebeck coefficient, electrical conductivity, and thermal conductivity of Ca₃Co_2−xMn_xO₆ with x = 0.05, 0.2, 0.5, 0.75, and 1 are reported. Powders of the materials were synthesized by the solid-state method, followed by conventional sintering. The material Ca₃CoMnO₆ (x = 1) demonstrated a large positive Seebeck coefficient of 668 μV/K at 900 °C, but very low electrical conductivity. Materials with compositions with x < 1 had lower Seebeck coefficients and higher electrical conductivity, consistent with small polaron hopping with an activation energy for mobility of 44 ± 6 kJ/mol and where both the concentration and mobility of hole charge carriers were proportional to 1−x. The conductivity reached about 11 S·cm⁻¹ at 900 °C for x = 0.05. The material Ca₃Co_1.8Mn_0.2O₆ (x = 0.2) yielded a maximum zT of 0.021 at 900 °C. While this value in itself is not high, the thermodynamic stability and self-assembly of Ca₃Co_2−xMn_xO₆ layers between Ca₃Co_4−yO_9+δ and CaMnO_3−δ open for new geometries and designs of oxide-based thermoelectric generators.

【 授权许可】

Unknown