High thermoelectric figure of merit and thermopower in layered perovskite oxides

Fiorentini, Vincenzo;Farris, Roberta;Argiolas, Edoardo;MacCioni, Maria Barbara

2019-01-01

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Abstract

We predict high thermoelectric efficiency in the layered perovskite La2Ti2O7, based on calculations (mostly ab initio) of the electronic structure, transport coefficients, and thermal conductivity in a wide temperature range. The figure of merit ZT computed with a temperature-dependent relaxation time increases monotonically from just above 1 at room temperature to over 2.5 at 1200 K, at an optimal carrier density of around 1020cm -3 . The Seebeck thermopower coefficient is between 200 and 300μV/K at optimal doping, but can reach nearly 1 mV/K at low doping. Much of the potential of this material is due to its lattice thermal conductivity of order 1 W/(K m); using a model based on ab initio anharmonic calculations, we interpret this low value as due to effective phonon confinement within the layered-structure blocks.