Synthesis and electrical transport properties of Er1-xScxNiSb semiconducting solid solution

L Romaka,Yu Stadnyk,P Klyzub,V Pashkevych,A Horyn,P Garanyuk,V.A Romaka

doi:10.15330/pcss.22.1.146-152

Abstract

Samples of Er1-xScxNiSb (x = 0–0.10) solid solution were synthesized by an arc-melting and the effect of doping by Sc atoms on the electrokinetic and energetic characteristics of the half-Heusler ErNiSb phase was investigated. It was established that at the studied concentrations the main carriers of electricity in the Er1-xScxNiSb semiconductor are holes. It was shown that doping of p-ErNiSb compound by Sc atoms introduced by substitution of Er atoms in 4a position is accompanied by the occupation of presented vacancies in position 4a, which leads to the reduction and elimination of structural defects of acceptor nature and corresponding acceptor band. The concentration ratio of ionized acceptors and donors generated in Er1-xScxNiSb determines the position of the Fermi level and the mechanisms of electrical conduction. The investigated solid solution Er1-xScxNiSb is a promising thermoelectric material.

Highlights

One of the ways to obtain thermoelectric materials based on half-Heusler phases with high efficiency of thermal energy conversion into electricity is doping of basic semiconductors, in particular, n-MNiSn, n-MCoSb and n-VFeSb (M = Ti, Zr, Hf), by impurity atoms, which generates structural defects of the neutral, donor and/or acceptor nature
The introduction into the p-ErNiSb semiconductor impurity Sc atoms by substitution of Er atoms in position 4a is accompanied by the occupation of Sc atoms of available in the compound vacancies in the crystallographic position 4a, which results in the reduction and elimination of structural defects of acceptor nature and corresponding acceptor band εАEr
The structural defects of donor nature are generated in the 4a position, and an impurity donor band εDSc appears

Summary

Introduction

One of the ways to obtain thermoelectric materials based on half-Heusler phases (structure type MgAgAs, space group F4-3m [1, 2]) with high efficiency of thermal energy conversion into electricity is doping of basic semiconductors, in particular, n-MNiSn, n-MCoSb and n-VFeSb (M = Ti, Zr, Hf), by impurity atoms, which generates structural defects of the neutral, donor and/or acceptor nature. This doping allows to change smoothly the values of the thermopower coefficient , the electrical conductivity σ, and the thermal conductivity in a semiconductor and to obtain high values of the thermoelectric figure of merit Z (Z = 2 σ/ ) [2, 3].

Experimental details

Crystalline and electronic structures modeling of Er1-xScxNiSb

Study of electrokinetic and energetic characteristics of Er1-xScxNiSb

Conclusions