High Pressure-Temperature Studies of Vanadium

Vanadium, a seemingly simple metal, has captured the interest of high-pressure scientists following the discovery (Ding et al. PRL 2007) of a subtle pressure-induced phase transition from bcc to a rhombohedral phase. Recent first-principles electronic-structure studies (Lee et al. PRB 2007) are consistent with these experiments and extend beyond the range of the measurements, predicting a reentrant phase transition back to bcc at high pressure. Further experiments in the regime of these predictions can validate and advance the understanding of simple metals at high-pressures. We have made x-ray diffraction measurements of the crystal structure and lattice parameters of vanadium at high-pressure and temperature. Detailed comparisons will challenge/validate models and guide development of predictive codes. We will discuss our measurements including high temperature behavior, the EOS, and transitions of vanadium at high pressure.