Unraveling the relationships between chemical bonding and thermoelectric properties: n-type ABO3 perovskites

Abstract

Establishing the relationships between chemical bonding and functional properties is at the core of condensed matter and materials science and is key to the rational design of novel materials. High-throughput (HTP) studies provide an opportunity to explore large sets of materials thereby enabling a global view of relationships between bonding and properties. Here we use HTP methods to investigate ABO₃ cubic perovskites for n-type thermoelectric properties. Of the 313 ABO₃ entries investigated, 46 are found to have a finite band gap and meet the lattice stability criterion. Four distinctly different structures of conduction band minima (CBMs) are identified. These are based on classification by the band degeneracy and location of the band edge. These four types of CBMs arise from four different types of chemical bonding; compounds with triply degenerate CBMs from B-site t_2g orbitals have both the largest density of states near the CBM and the most favorable Pisarenko curves. They also possess the best electrical transport properties including consideration of the relaxation times from the deformation potential approximation. When the calculated electrical transport properties are combined with the lattice thermal conductivity, 13 ABO₃ perovskites with high ZT (ZT > 0.5) values at 700 K are identified as n-type candidates. This work demonstrates the importance of chemical bonding in determining transport properties.