ATiO3 (A = Ca, Sr, Ba) oxide perovskites as high-performance thermoelectrics Alveena Z. Khan, Joseph M. Flitcroft, Jonathan M. Skelton University of Manchester, UK All machines of various shapes and sizes generate heat. For example, in an internal combustion engine up to 60% of the energy consumed is wasted as heat. 1 Technologies for efficiently recovering this waste heat as useful electrical energy would help to improve energy efficiency and contribute significantly to the fight against climate change. Thermoelectric generators (TEGs) are solid-state devices that can directly convert thermal energy to electrical power via the Seebeck effect. TEGs also have no moving parts and are easily scalable to a wide range of applications. Oxide materials are attractive for thermoelectric applications due to their low toxicity, low cost, high abundance and chemical robustness, making them of interest for high-temperature automotive and industrial applications. However, most oxides tend to have low electrical conductivity and high thermal conductivity, which limit their thermoelectric performance. There has therefore been substantial research into enhancing their electrical conductivity and suppressing the thermal transport, for example by doping and alloying. However, experimentally finding the optimal set of conditions is costly and time consuming due to the many competing parameters that require optimisation. We have used first-principles modelling to study the thermal and electronic properties of three Group 2 perovskites ATiO 3 (A = Ca, Sr, Ba). We perform lattice-dynamics calculations, including explicit computation of the phonon lifetimes, to evaluate the lattice thermal conductivity, which shows that these perovskites have relatively low thermal conductivity, especially at high temperature. We also use the AMSET code 2 to model the electrical transport properties as a function of temperature and carrier concentration, thereby allowing us to predict thermoelectric performance, expressed by the dimensionless figure of merit ZT. This modelling workflow, and the insight from this study, lays the foundation for theoretical studies on other ternary and higher oxide materials as potential high-performance TEs. References 1. R. Freer and A. V. Powell, J. Mater. Chem. C , 2020, 8 , 441–463. 2. A. M. Ganose, J. Park, A. Faghaninia, R. Woods-Robinson, K. A. Persson and A. Jain, Nat. Commun. , 2021, 12 , 2222.
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