Special Issue Oxide Thermoelectric Materials for Heat-to-Electricity Direct Energy Conversion

Rapid progress in thermoelectric performance of oxide materials has been conducted virtually exclusively in Ja-pan, resulting in more than 10 times increase in the ZT values of oxides within the last two decades. This has caused a revolutionary change in the guiding principles of thermoelectric materials research, in which oxide materials had been disregarded as a potential candidate until early 1990s. Promising oxide thermoelectric materials having been discovered include CaMnO3-based perovskites, Al-doped ZnO, layered cobalt oxides represented by NaCo2O4 and Ca3Co4O9, and SrTiO3-related phases. This paper reviews the current aspects of oxide thermoelectric materials, and some strategies for selective reduction of the lattice thermal conductivity (selective phonon scattering) in bulk oxide ceramics will also be discussed