The pressure and temperature dependence of the structure of CoCr2S4 and Co0.65Ni0.35Cr2S4 have been studied by in situ time-of-flight powder neutron diffraction. While the thiospinel CoCr2S4 transforms to a defect NiAs-type phase at 1.3 GPa and 800 °C, the nickel-doped thiospinel undergoes this phase change at 0.4 GPa and 750 °C. Quenching of the hexagonal high-temperature and high-pressure phase resulted in a transition to a monoclinic Cr3S4 phase, due to the ordering of the metal vacancies in every second layer. Moreover, the spinel CoCr2S4 transforms at room temperature and 8.6 GPa to a phase which does not exhibit a NiAs-type structure.
|Number of pages||6|
|Journal||Physical Review B: Condensed Matter and Materials Physics|
|Publication status||Published - 2001|