Effect of pressure on the atomic volume of Zn, Cd, and Hg up to 75 GPa

The elemental metals Zn, Cd, and Hg are studied under pressure in a diamond-anvil cell by energy-dispersive x-ray diffraction. While Zn and Cd remain in the hP2 structure up to the highest pressures achieved, several phase transitions are observed in Hg with a hP2 structure for the high-pressure {δ}-Hg phase. Different equation of state (EOS) forms are fitted to these experimental data and, for comparison, also to literature data of Be and Mg. A detailed analysis of the data shows that a simple one parameter EOS form describes the isothermal behavior of almost all the phases. Only the intermediate {γ}-Hg phase shows slight deviations from this ``simple'' EOS behavior. {} 1996 The American Physical Society.