Thermoelectric power of mixed electronic-ionic conductors III. Case of calcium titanate

Abstract

Abstract. The primary purpose of the present work is the determination of the thermopower component related to electronic charge carriers for undoped calcium titanate. The second purpose of this work is establishment of the relationship between this thermopower component and the electronic component of electrical conductivity. An essential part of the present study includes the determination of the thermopower components corresponding to different charge carriers (electrons, electron holes and ions). The determination procedures are based on the following three models:9 Symmetrical model. This model assumes consistency between thermopower and electrical conuctivity in terms of the n-p transition (this model assumes that minimum of electrical conductivity corresponds to the electronic component of the thermopower equal zero). It was shown that this model does not apply for CaTiO3. 9 The Heikes model. This model is based on Heikes formula and also hopping mechanism of the transport of electrons. It was shown that thermopower of CaTiO 3 cannot be described by this model and, consequently, thermopower vs. electrical conductivity cannot be considered within the Jonker formalism.

Controlling Precipitation and Dopant Effects To Achieve Promising Thermoelectric Performance in CaTiO3

“…The reported TE properties of pristine CaTiO 3 are mainly obtained through theoretical calculations. − Attou et al predicted that the zT value of B-doped CaTiO 3 (B@Ca) can reach 0.56 at 800 K . Bak et al observed a n-p type transformation in the Seebeck coefficient of CaTiO 3 at high temperatures (1173–1323 K) under different oxygen partial pressures. , It indicates that the presence of oxygen vacancies can lead to an n -type conduction behavior. However, for experimental studies, CaTiO 3 sintered in air demonstrates a remarkably high resistance, resulting in extremely poor thermoelectric properties.…”