Specific microstructural effects on the performance of thermoelectric oxides

Oxide materials possess notable high-temperature and chemical stability, thus representing certain advantages over traditional thermoelectrics. The thermoelectric performance of oxides is strongly affected by the microstructure, often even dominating over the chemical composition effects. Thus, engineering the microstructure in these materials represents a powerful tool towards improving their thermoelectric performance, both in terms of the maximum output and stable operation at elevated temperatures. This work reviews some representative cases observed for the main thermoelectric oxide families, such as ZnO, SrTiO3, Ca3Co4O9 and CaMnO3-based systems. The selected examples highlight the impacts of the relevant microstructural features, including the presence of porosity, phase morphology and interfaces, on the thermoelectric properties and their evolution with time.publishe