High-pressure effects on the electrical resistivity and structure of single-crystal cadmium sulphide

Electrical resistivity and structural changes resulting from pressure-induced transitions in single-crystal cadmium sulphide are examined at room temperature under hydrostatic and quasi-hydrostatic pressure conditions (of the order of 3.5 GPa). The abrupt transition from the initial wurtzite phase to the rocksalt phase is shown to occur at 2.31 +- 0.02 GPa under hydrostatic pressure. Experiments on low-resistivity (0.5 to 8 Ω cm), high resistivity (108 to 109 Ω cm), and neutron-irradiated (1016 to 1017 n cm-2) single crystals show that this transition is not significantly affected by crystal imperfections or lattice damage. The resistivity in the high-pressure rocksalt phase is 3 to 8 Ω cm and is independent of the initial (wurtzite) sample resistivity. Upon release of pressure the samples transform to a high-resistivity (107 to 109 Ω cm) phase at 1.2 to 1.5 GPa. The resistivity of the recovered material is independent of the initial sample resistivity. This material is also photoconductive and has a low mobility. X-Ray diffraction experiments show that the recovered samples are predominantly of the wurtzite phase. Data are also presented on single-crystal cadmium selenide. (author)