X-ray diffraction evidence for a ferroelectric phase transition in zinc cadmium telluride

X-ray diffraction measurements on ZnxCd1−xTe were made on samples with x = 0.00, 0.10, 0.30 and 0.45. The measurements were made both at room temperature, i.e. below the transition temperature, and well above the transition. We have found a distinct splitting of the diffraction lines in the low temperature phase. The room temperature measurements were compared with the high temperature spectra where the splitting disappears. From the line positions and intensities at room temperature it was found that the spectra are consistent with a rhombohedral structure with the tellurium atom displaced from the central position. The rhombohedral angle was found to be 89.4±0.1°, and the displacement of the tellurium from the centre (11±2) × 10−2A. The distortions were the same for all zinc-containing samples and were found to be consistent with theoretical calculations. The non-cubic structure of the low temperature phase supports the observation of ferroelectricity in materials that have the zinc blende structure in their high temperature phase.