  The pressure-induced insulator to metal transition (IMT) of layered magnetic
nickel phosphorous tri-sulfide NiPS3 was studied in-situ under quasi-uniaxial
conditions by means of electrical resistance (R) and X-ray diffraction (XRD)
measurements. This sluggish transition is shown to occur at 35 GPa. Transport
measurements show no evidence of superconductivity to the lowest measured
temperature (~ 2 K). The structure results presented here differ from earlier
in-situ work that subjected the sample to a different pressure state,
suggesting that in NiPS3 the phase stability fields are highly dependent on
strain. It is suggested that careful control of the strain is essential when
studying the electronic and magnetic properties of layered van der Waals
solids.
