Exploring the behavior of vanadium under high-pressure and high-temperature conditions

TL;DR

This study combines experimental and theoretical approaches to accurately determine vanadium's melting curve, phase transitions, and equation of state under high-pressure and high-temperature conditions, providing insights consistent with some prior methods but differing from others.

Contribution

It provides a comprehensive and consistent set of data on vanadium's melting behavior and structural phases at extreme conditions, improving upon previous measurements and calculations.

Findings

Melting curve of vanadium accurately determined up to 120 GPa.

Identified the bcc-to-rhombohedral phase transition boundary.

Established an equation of state up to 120 GPa and 2800 K.

Abstract

We report a combined experimental and theoretical study of the melting curve and the structural behavior of vanadium under extreme pressure and temperature. We performed powder x-ray diffraction experiments up to 120 GPa and 4000 K, determining the phase boundary of the bcc-to-rhombohedral transition and melting temperatures at different pressures. Melting temperatures have also been established from the observation of temperature plateaus during laser heating, and the results from the density-functional theory calculations. Results obtained from our experiments and calculations are fully consistent and lead to an accurate determination of the melting curve of vanadium. These results are discussed in comparison with previous studies. The melting temperatures determined in this study are higher than those previously obtained using the speckle method, but also considerably lower than those obtained from shock-wave experiments and linear muffin-tin orbital calculations. Finally, a high-pressure high-temperature equation of state up to 120 GPa and 2800 K has also been determined.