Electronic structure and low temperature thermoelectric properties of In₂₄ M₈ O₄₈ (M = Ge⁴⁺, Sn⁴⁺, Ti⁴⁺, and Zr⁴⁺)

Abstract

The electronic structure and transport properties of In₂₄M₈O₄₈ (M = Ge(4+), Sn(4+), Ti(4+), and Zr(4+)) have been studied by using the full-potential linearized augmented plane-wave method and the semiclassical Boltzmann theory, respectively. It is found that the magnitude of powerfactor with respect to relation time follows the order of In₂₄Sn₈O₄₈ > In₂₄Zr₈O₄₈ > In₂₄Ge₈O₄₈ > In₂₄Ti₈O₄₈. The largest powerfactor is 2.7 × 10¹² W/K² ms for In₂₄Sn₈O₄₈ at 60 K, which is nearly thirty times larger than those of conventional n-type thermoelectric materials. The origin of the different thermoelectric behavior for these compounds is discussed from the electronic structure level. It is found that, at low temperature, the dopant strongly affect the bands near the Fermi level, which consequently leads to their different thermoelectric properties. The electronic configuration and the difference in atomic number between the dopant and the host atom also play an important role on the thermoelectric properties of In₂₄M₈O₄₈. Our calculations give a valuable insight on how to enhance the thermoelectric performance of In₃₂O₄₈.

High Power Factor vs. High zT—A Review of Thermoelectric Materials for High-Temperature Application

“…Undoped In 2 O 3 is a semiconductor with a band gap of 1.2 eV that can be strongly influenced via doping. The crystal structure can be described as a cubic bixbyite structure with two nonequivalent cation sites that can be substituted with different dopants [ 88 ]. The electron effective mass as well as the carrier concentration of this material strongly depend on the amount of doping within the structure.…”

A comprehensive study on improved power materials for high-temperature thermoelectric generators

“…The influence of these different processing techniques on the thermoelectric properties were compared, since HP and SPS are fast and partly reducing, while pressureless sintering in air and O 2 , are oxidizing techniques. These dense nanocomposite ceramics were combined with recently developed, co-doped n-type indium oxides [40,41,42] in thermoelectric generators. The impact of high zT and high power factor materials on the electrical power output at high temperatures in air from infinite heat sources, as postulated by Narducci [43], were verified.…”