ZnTe at high pressure: X-ray-absorption spectroscopy and x-ray-diffraction studies

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Abstract
ZnTe has been studied by x-ray-absorption spectroscopy at the Zn K edge and by x-ray diffraction up to 30 GPa. Crystallographic transitions were observed at 9.5 and 12 GPa by both techniques. The combination of x-ray-absorption near-edge structure, extended x-ray-absorption fine structure, and diffraction analysis enables us to determine the structure of ZnTe-II which is cinnabar with two pairs of first neighbors at approximately the same distance (∼2.558 Å at 11.7 GPa), maintaining the fourfold coordination, the third pair of neighbors being much farther (∼3.37 Å). At 12 GPa ZnTe-II destabilizes and gives rise to a distorted rocksalt-type coordination, which remains stable at least up to 30 GPa. The succession of transitions is structurally reversible and takes place without amorphization. The hysteresis of the transitions has also been studied. A Murnaghan equation of state fitted to the values of the ZnTe cell parameter in ZnTe-I gives a bulk modulus of 50.5±3 GPa in good agreement with previous work.