Structural behaviour of NiS₂ up to 54 kbar

Abstract

Single-crystal X-ray diffraction experiments were carried out on NiS₂ under high pressures with the aid of a diamond-anvil cell. The pressure dependence of the a dimension was found to be linear over the experimental pressure range across the transition point with a good approximation. The S–S bond length is practically constant up to the transition pressure and decreases rapidly above it. The Ni–S length decreases with pressure both in the semiconductor and metallic phases within the pressure range of this experiment. However, the decrement is slower in the higher pressure, metallic phase than in the semiconductor phase. Discontinuities in the plots of bond lengths against pressure are not so large as can be recognized with the precision of this experiment.