Phase transitions in vanadium at high pressures*

Vanadium metal behavior under high pressure conditions has been the subject of several studies in recent years, both experimental and theoretical. The body centered cubic to rhombohedral phase transition has been reported first experimentally, followed by several theoretical studies, which predict a second rhombohedral phase and ultimately, above 3 megabar pressure, the reentry into the stable high pressure bcc phase. Experimentally, in polycrystalline samples, so far only the lower pressure rhombohedral phase has been reported and only one single crystal experiment reports the higher pressure, second rhombohedral phase. In this report we present experimental results of vanadium compressed in neon pressure medium and without pressure medium to above 3 megabar pressures and will address the stability of the rhombohedral phase of vanadium.