Pressure-Temperature Phase Diagram and Crystal Structure of NiS

The antiferromagnetic phase of NiS is suppressed at pressures in excess of 20 kbar and no anomalous behavior is observed in the temperature dependence of the resistivity above the critical pressure. Single-crystal x-ray diffraction studies set a limit on the movement of the sulfur atoms in the antiferromagnetic phase from the centrosymmetric position ($z=\frac{1}{4}$) of $z=0.\mathrm{}252\pm 0.002$.