Pressure fixed points between 100 and 200 kbar based on the compression of NaCl

Abstract

Transformation pressures in three materials, Pb, ZnS, and GaAs, were measured by means of an x‐ray diffraction technique using NaCl as an internal pressure standard. A cubic‐anvil type of high‐pressure apparatus and a high‐power x‐ray diffraction system were used for this study. Based on Decker′s equation of state for NaCl, transition pressures in the increasing and decreasing pressure cycle were determined as follows: for Pb 142±3 and 111±2 kbar, for ZnS 162±4 and 110–100 kbar, and for GaAs 193±5 and 115–100 kbar. These values and the high Ba transformation pressure reported from this laboratory (126±2 and 111±2 kbar in the increasing and decreasing pressure cycle) form a set of pressure fixed points between 100 and 200 kbar at room temperature.