Synthesis, differential thermal analysis, and crystal structure of the quaternary chalcogenide compound Cu₂FeGeTe₄

This study reports on the quaternary diamond-like semiconductor copper iron germanium tellurium, Cu₂FeGeTe₄. The material was synthesized using the melt and annealing technique by directly reacting the elements. The thermal behavior of the Cu2FeGeTe4 compound was investigated using thermogravimetric analysis. The Rietveld refinement method characterized the crystal structure through X-ray powder diffraction. The powder diffraction pattern revealed that the principal phase, Cu2FeGeTe4, constituted 85.4%, while the secondary phase, FeTe2, accounted for 14.6%. The quaternary chalcogenide compound Cu2FeGeTe4 belongs to the I2-II-IV-VI4 system and crystallizes in the stannite structure within the non-centrosymmetric tetragonal space group I-42m (N^◦ 121), Z = 2, with unit cell parameters a = 5.9293(8) Å, c = 11.9239(8) Å, V = 419.20(2) ų. Its structure consists of a three-dimensional close-packed arrangement of slightly distorted CuTe4, FeTe4, and GeTe4 tetrahedra, interconnected through shared faces and corners. The chemical structure was verified through Bond Valence Sum (BVS) calculations.