Experimental studies of a new thermoelectric material based on semiconductor solid solution Ti1-xAlxNiSn

Yu. Stadnyk; V.A. Romaka; L. Romaka; A. Horyn; V. Pashkevych

doi:10.15330/pcss.25.1.157-163

Authors

Yu. Stadnyk Ivan Franko National University of Lviv, Lviv, Ukraine
V.A. Romaka Lviv Polytechnic National University, Lviv, Ukraine
L. Romaka Ivan Franko National University of Lviv, Lviv, Ukraine
A. Horyn Ivan Franko National University of Lviv, Lviv, Ukraine
V. Pashkevych Lviv Polytechnic National University, Lviv, Ukraine

DOI:

https://doi.org/10.15330/pcss.25.1.157-163

Keywords:

Semiconductor, Electric conductivity, thermopower coefficient, Fermi level

Abstract

The structural, electrokinetic, and energetic properties of the Ti_1-xAl_xNiSn semiconductor solid solution, obtained by introducing of Al atoms into the structure of the TiNiSn half-Heusler phase by substituting Ti atoms in the crystallographic position 4a, were studied. It is shown that in the range of concentrations x = 0–0.01, Al atoms mainly replace Ni atoms in the 4c position, generating acceptor states. It was established that at temperatures T = 80–160 K, the ratio of concentrations of ionized acceptor and donor states in n-Ti_1-xAl_xNiSn, х = 0–0.04, is unchanged, but the concentration of donors is greater. At higher temperatures, T ≥ 250 K, deep donor states that existed in n-TiNiSn as a result of "a priori doping" of the semiconductor are ionized. An additional mechanism for the generation of donor states in n-Ti_1-xAl_xNiSn when the tetrahedral voids of the structure are partially occupied by Al atoms was revealed. The concentration ratio of the generated donor-acceptor states determines the position of the Fermi level ε_F and the conductivity mechanisms of n-Ti_1-xAl_xNiSn. The studied semiconductor solid solution is a promising thermoelectric material.

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