Thermoelectric and electrical properties of triple-conducting multicomponent oxides based on substituted barium...

Multicomponent oxides often have exceptional thermal stability and interesting electronic properties. The present work presents the thermoelectric and electrical properties of the Ba(Zr_0.2Hf_0.2Sn_0.2Ti_0.2Fe_0.2)O_3- and Ba(Zr_0.1Hf_0.1Sn_0.1Ti_0.1Co_0.1Ce_0.1Bi_0.1Fe_0.1Y_0.1Zn_0.1)O_3- multicomponent perovskites. Single-phase cubic perovskites were synthesized using the solid-state reaction method. They were characterized using X-ray diffraction, drop-solution calorimetry, and thermogravimetry methods. The total electrical conductivity and Seebeck coefficient measurements were performed in dry and wet air at temperatures between 600 and 1050 K. It was found that Ba(Zr_0.1Hf_0.1Sn_0.1Ti_0.1Co_0.1Ce_0.1Bi_0.1Fe_0.1Y_0.1Zn_0.1)O_3- is thermodynamically less stable than Ba(Zr_0.2Hf_0.2Sn_0.2Ti_0.2Fe_0.2)O_3-. Moreover, this oxide incorporates a higher amount of water and exhibits higher conductivity and lower Seebeck coefficient. Charge transport in both perovskites can be assigned to the small-polaron hopping process via electron holes. An interesting temperature dependence of the Seebeck coefficient was found and, at temperatures above 750 K, related to hopping between energetically inequivalent states.