Kanas Nikola, Singh Sathya Prakash, Rotan Magnus, Desissa Temesgen Debelo, Grande Tor, Wiik Kjell, Norby Truls, Einarsrud Mari-Ann
Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
Department of Chemistry, University of Oslo, FERMiO, Gaustadalléen 21, NO-0349 Oslo, Norway.
Materials (Basel). 2019 Feb 6;12(3):497. doi: 10.3390/ma12030497.
High-temperature instability of the Ca₃CoO and CaMnO direct p-n junction causing the formation of Ca₃CoMnO₆ 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 Ca₃CoMnO₆ with = 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 ( = 1) demonstrated a large positive Seebeck coefficient of 668 μV/K at 900 °C, but very low electrical conductivity. Materials with compositions with < 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-. The conductivity reached about 11 S·cm at 900 °C for = 0.05. The material Ca₃CoMnO₆ ( = 0.2) yielded a maximum of 0.021 at 900 °C. While this value in itself is not high, the thermodynamic stability and self-assembly of Ca₃CoMnO₆ layers between Ca₃CoO and CaMnO open for new geometries and designs of oxide-based thermoelectric generators.
Ca₃CoO和CaMnO直接p-n结的高温不稳定性导致Ca₃CoMnO₆的形成，这激发了对该中间相热电性能的研究。在此，报道了Ca₃CoMnO₆（ = 0.05、0.2、0.5、0.75和1）的热电性能，包括塞贝克系数、电导率和热导率。通过固态法合成材料粉末，随后进行常规烧结。材料Ca₃CoMnO₆（ = 1）在900°C时表现出668 μV/K的大正塞贝克系数，但电导率非常低。组成中 < 1的材料具有较低的塞贝克系数和较高的电导率，这与小极化子跳跃一致，其迁移激活能为44±6 kJ/mol，并且空穴电荷载流子的浓度和迁移率均与1-成正比。对于 = 0.05，在900°C时电导率达到约11 S·cm。材料Ca₃CoMnO₆（ = 0.2）在900°C时产生的最大 为0.021。虽然这个值本身并不高，但Ca₃CoMnO₆层在Ca₃CoO和CaMnO之间的热力学稳定性和自组装为基于氧化物的热电发电机的新几何形状和设计开辟了道路。
