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

TL;DR

This study investigates the melting behavior of tantalum under high pressure and temperature using angle dispersive x-ray diffraction in a laser-heated diamond-anvil cell, providing new experimental data and insights into its phase diagram.

Contribution

It presents the first comprehensive high-pressure melting curve of tantalum determined by angle dispersive x-ray diffraction in a laser-heated DAC, challenging some previous theoretical and experimental results.

Findings

Melting of Ta observed up to 52 GPa and 3800 K.

Melting temperatures agree with previous DAC experiments but contradict some theories.

Estimated a small slope for the melting curve of Ta (dTm/dP = 24 K/GPa).

Abstract

The high pressure and high temperature phase diagram of Ta has been studied in a laser-heated diamond-anvil cell (DAC) using x-ray diffraction measurements up to 52 GPa and 3800 K. The melting was observed at nine different pressures, being the melting temperature in good agreement with previous laser-heated DAC experiments, but in contradiction with several theoretical calculations and previous piston-cylinder apparatus experiments. A small slope for the melting curve of Ta is estimated (dTm/dP = 24 K/GPa at 1 bar) and a possible explanation for this behaviour is given. Finally, a P-V-T equation of states is obtained, being the temperature dependence of the thermal expansion coefficient and the bulk modulus estimated.