Electronic Nature and Thermoelectric Characteristics of Cubic LaPb₃ LaIn₃ and LaTl₃ Compounds: B3PW91 Approach

Abstract

In this paper the structural, electronic and transport properties of the strongly correlated intermetallics LaX₃ (X=Pb, In and Tl) in the space group Pm-3m (221) have been investigated using B3PW91 hybrid functional within the framework of density functional theory. These compounds have 4f orbitals and hence strong electron-electron correlation effect is expected, therefore, the electronic properties are also calculated with the B3PW91 hybrid functional and the effect of B3PW91 hybrid functional on the density of states is discussed in details. The band structure and density of states, demonstrate the metallic nature of these compounds. Using the semi-empirical Boltzmann’s approach implemented in the BoltzTraP code, the transport parameters, such as the Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit as a function of the chemical potential are computed at a temperature gradient of 500 K. For all materials the thermal and electrical conductivities, and Seebeck coefficient has higher values for n-type doping in comparison with p-type doping. The moderate values of figure of merit obtained for these materials indicate that these materials have applicability where small values of thermoelectric efficiency are required and higher values can harm the process but need experimental verification. LaIn₃ has the highest value of electrical conductivity per relaxation time and thermal conductivity per relaxation time are 9.43 x 10²⁰ 1/Ωms and 107.65 x 10¹⁴ W/mKs respectively. LaTl₃ has the highest figure of merit among these materials.