Enhanced thermoelectric performance in Ca substituted Sr3SnO

TL;DR

This study demonstrates a 45% enhancement in thermoelectric efficiency of Sr3SnO through Ca substitution, supported by first-principles calculations revealing changes in electronic and thermal properties.

Contribution

The paper provides new insights into how Ca substitution improves thermoelectric performance in Sr3SnO, including detailed mechanisms and computational validation.

Findings

ZT of Sr2CaSnO at 500K is 0.6

Seebeck coefficient reaches 219 μV/K for optimized hole concentration

Lattice thermal conductivity closely matches experimental data

Abstract

We report 45% enhancement in the thermoelectric figure of merit, ZT of Sr3SnO via Ca substitution. First-principles calculations have been performed to study the electronic and thermoelectric transport properties of Ca substituted Sr3SnO (Sr3-xCaxSnO). The effects of Ca subtitution on bandgap are studied and detailed mechanisms are proposed to explain the obtained results. We have found that effective mass and thermopower of Sr3SnO redueces with the increase of hole concentration. The optimum hole concentration has been obtained for Sr2CaSnO and the corresponding Seebeck coefficient is 219 {\mu}V/K. The electrical conductivity of Sr3SnO and its alloys exhibits semiconducting nature which contradicts with experimental results in Ca3SnO. We have found that due to the Ca-deficiency, the Ca3SnO shows the metallic conductivity and removes this contradiction with our results. The lattice thermal conductivities (\kl) of Sr3SnO and Ca3SnO have been calculated by using both PBE and GW functionals. The lattice thermal conductivity obtained by PBE functional largely underestimates the experimental value for Ca3SnO. The total thermal conductivity (with kl obtained by GW) at 300K is 2.33 and 1.897 W/mK for Sr3SnO and Ca3SnO, respectively, with excellent agreement with experimental value 1.707 W/mK for Ca3SnO. The dimensionless figure of merit (ZT) for Sr2CaSnO at 500 K is 0.6 and making it promising for thermoelectric applications.