Melting of tantalum at high pressure determined by angle dispersive x-ray diffraction in adouble-sided laser-heated diamond-anvil cell

Abstract

The high-pressure and high-temperature phase diagram of Ta has been studied in alaser-heated diamond-anvil cell (DAC) using x-ray diffraction measurements up to 52 GPaand 3800 K. The melting was observed at nine different pressures, the melting temperaturebeing in good agreement with previous laser-heated DAC experiments, but incontradiction with several theoretical calculations and previous piston–cylinderapparatus experiments. A small slope for the melting curve of Ta is estimated( at 1 bar) and a possible explanation for this behaviour is given. Finally, aP–V –T equation of states is obtained, the temperature dependence of the thermal expansioncoefficient and the bulk modulus being estimated.