Investigation of the structural, electronic, thermoelectric, and thermal transport properties of zıntl BaIn2Te4 material from first principles

In this study, the structural, electronic, lattice dynamical, thermoelectric and thermal transport properties of the tellurium-based BaIn2Te4 material were investigated theoretically. Total energy and lattice dynamical calculations have been performed on the basis of density functional theory (DFT) and using the generalized gradient approach (GGA). The calculation of the thermoelectric coefficients was obtained by solving the electronic Boltzmann transport equation under the relaxation time approximation. Phonon transport properties are also obtained from the linearized phonon Boltzmann transport equation. Equilibrium lattice parameters obtained without using experimental parameters are in good agreement with the experiment together with internal parameters. The indirect band-gap was found in the electronic band structure calculations and the gap value was obtained as 0.963 eV at the GGA limits. Phonon distribution curves are positive, showing that the structure is dynamically stable. Among the thermoelectric coefficients we have calculated, the Seebeck coefficient has been found to have higher values for p-type doping compared to n-type at similar carrier concentrations. The lattice thermal conductivity of BaIn2Te4 was found to be anisotropic, and its average was found to be in perfect agreement with the experiment. It was observed that the ZT value, all calculated with the theoretically obtained quantities, was 0.25 and below at room temperature, and it reached high values at medium and high temperatures. Especially in p-type doping, values higher than ZT>1 have been reached starting from 500K. In n-type doping, on the other hand, ZT>1 value is reached starting from about 700K temperature.