Investigating the high-temperature thermoelectric properties of n-type rutile TiO$_2$

TL;DR

This paper theoretically investigates the high-temperature thermoelectric properties of n-type rutile TiO₂, using ab initio calculations and models to compare with experimental data, aiming to identify its potential as a thermoelectric material.

Contribution

It provides a detailed theoretical analysis of rutile TiO₂'s thermoelectric properties, validating band conduction and predicting high-temperature performance.

Findings

Good agreement with experimental data across carrier concentrations

Band conduction is confirmed in rutile TiO₂

Potential for high thermoelectric efficiency at elevated temperatures

Abstract

Transition metal oxides are considered promising thermoelectric materials for harvesting high-temperature waste heat due to their stability, abundance and low toxicity. Despite their typically strong ionic character, they can exhibit surprisingly high power factors $\sigma S^2$, as in n-type SrTiO$_3$ for instance. Thus, it is worth examining other transition metal oxides that might surpass the performances of SrTiO$_3$. This theoretical paper investigates the thermoelectric properties of n-type rutile TiO$_2$, which is the most stable phase of titanium oxide up to 2000 K. The electronic structure is obtained through ab initio calculations, while the prominent features of strong electron-phonon interaction and defects states are modelled using a small number of parameters. The theoretical results are compared with a wealth of experimental data from the literature, yielding very good agreements over a wide range of carrier concentrations. This validates the hypothesis of band conduction in rutile TiO$_2$ and allows the prediction of the high-temperature thermoelectric properties.