The Cu 2 GeTe 3 compound crystallizes in the Imm2 (N° 44) space group, Z = 2, with a = 12.641(1) Å, b = 4.2115(2) Å, c = 5.9261(2) Å, V = 315.49(3) Å 3 . Its structure was refined from X-ray powder diffraction data using the Rietveld method. The refinement of 23 instrumental and structural variables led to R p = 8.2%, R wp = 11.6%, R exp = 6.8%, R B = 11.2 % and S = 1.7, for 5501 step intensities and 253 independent reflections. This compound is isostructural with Cu 2 GeSe 3 , and consists of a three-dimensional arrangement of slightly distorted CuTe 4 and GeTe 4 tetrahedra connected by common corners.

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A dynamic pulse‐echo overlap method is used to measure the longitudinal and transverse sound velocities of polycrystalline samples of CuInTe2 and CuInSe2 between 4.2 and 300 K. From these measurements the temperature dependence of the elastic moduli is obtained. From the low temperature value of the average sound velocity, the Debye temperature is calculated to be 197.5 and 243.7 K for CuInTe2 and CuInSe2, respectively. Using the Szigeti relationships the ionicities are estimated to be 0.39 and 0.34 for CuInSe2 and CuInTe2, respectively.

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