(Cu0.4Al0.3)TaSe2: PREPARATION AND CRYSTAL STRUCTURE ANALYSIS FROM X-RAY POWDER DIFFRACTION

Abstract

A new phase of the (CuAlSe2)1-x(TaSe)x alloy system was synthesized by the melt and annealing technique and studied by SEM, DTA, and XRPD techniques. Its structure has been refined by the Rietveld method using X-ray powder diffraction data. The new alloy corresponds with the stoichiometry Cu0.4Al0.3TaSe2. This compound crystallizes in the hexagonal space group 𝑃6ത𝑚2 (Nº 187) with a MoS2-type structure, and unit cell parameters a = 3.455(2) Å, c = 13.423(4) Å, V = 138.7(1) Å3, Z =2. The crystal structure is based on the MoS2- type of stacking of TaSe2 layers with a partial ordering of Cu and Al cations over the tetrahedral sites. The powder pattern was composed of 63.1% of the principal phase Cu0.4Al0.3TaSe2 and 29.9% of CuAlSe2, 7.0% of TaSe3, as the secondary phases.