BaBi2O6: A Promising n-Type Thermoelectric Oxide with the PbSb2O6 Crystal Structure

Thermoelectric materials offer the possibility of enhanced energy efficiency due to waste heat scavenging. Based on their high-temperature stability and ease of synthesis, efficient oxide-based thermoelectrics remain a tantalizing research goal; however, their current performance is significantly lower than the industry standards such as Bi2Te3 and PbTe. Among the oxide thermoelectrics studied thus far, the development of n-type thermoelectric oxides has fallen behind that of p-type oxides, primarily due to limitations on the overall dimensionless figure of merit, or ZT, by large lattice thermal conductivities. In this article, we propose a simple strategy based on chemical intuition to discover enhanced n-type oxide thermoelectrics. Using state-of-the-art calculations, we demonstrate that the PbSb2O6-structured BaBi2O6 represents a novel structural motif for thermoelectric materials, with a predicted ZT of 0.17-0.19. We then suggest two methods to enhance the ZT up to 0.22, on par with the current best earth-abundant n-type thermoelectric at around 600 K, SrTiO3, which has been much more heavily researched. Our analysis of the factors that govern the electronic and phononic scattering in this system provides a blueprint for optimizing ZT beyond the perfect crystal approximation.