CRYSTAL STRUCTURE OF THE QUATERNARY SEMICONDUCTOR COMPOUND CuFeCrSe3

Abstract

The compounds with ternary structures of the chalcopyrite family Cu-III-Se2 (III = Al, Ga, In, Cr) form a wide group of semiconductor materials with diverse optical and electrical properties, and the addition of FeSe binary compound produces alloys of the type (Cu-III-Se2)1-x(Fe-Se)x. These types of materials have received increasing attention as promising thermoelectric materials due to their high efficiency, tunable transport properties, high elemental abundance and low toxicity. This work aims to synthesize and characterize structurally a new material belonging to this semiconductor system with x = ½, the quaternary compound CuFeCrSe3. This material was prepared by the melt and anneal technique and its structure was refined from Xray powder diffraction pattern using the Rietveld method. The X-ray powder pattern was mainly composed of CuFeCrSe3 (79.1%) with CuCr2Se4 (20.9%) appearing as secondary phase. The principal phase crystallizes with tetragonal symmetry in the space group P 4 2c (Nº 112), Z = 1, with a = 5.5082(2) Å, c = 10.943(1) Å, V = 332.01(1) Å3. The refinement of 18 instrumental and structural parameters led to Rp = 8.8 %, Rwp = 9.1 %, Rexp = 7.8 % and S = 1.2. This material, belonging to the semiconductor system I-II-III-VI3, crystallizes with a CuFeInSe3-type structure in a normal adamantane-structure. CuFeCrSe3 is a new semiconductor compound, related to the superionic phase CuCrSe2, and can be considered as a potential candidate for mediumtemperature thermoelectric applications.