Phonon Triggered Rhombohedral Lattice Distortion in Vanadium at High Pressure

Daniele Antonangeli1, Daniel L. Farber2, Alexei Bosak3, Chantel M. Aracne4, David G. Ruddle4 & Michael Krisch3 2016. “Phonon Triggered Rhombohedral Lattice Distortion in Vanadium at High Pressure.” Scientific Reports 6 (August)

1Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), UMR CNRS 7590, Sorbonne Universités - UPMC, Muséum National d’Hystoire Naturelle, IRD, 75252 Paris, France.

2Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, California 95063, USA.

3European Synchrotron Radiation Facility, 38000 Grenoble, France.

4Lawrence Livermore National Laboratory, Livermore, California 94550, USA.

In spite of the simple body-centered-cubic crystal structure, the elements of group V, vanadium, niobium and tantalum, show strong interactions between the electronic properties and lattice dynamics. Further, these interactions can be tuned by external parameters, such as pressure and temperature. We used inelastic x-ray scattering to probe the phonon dispersion of single-crystalline vanadium as a function of pressure to 45 GPa. Our measurements show an anomalous high-pressure behavior of the transverse acoustic mode along the (100) direction and a softening of the elastic
modulus C44 that triggers a rhombohedral lattice distortion occurring between 34 and 39 GPa. Our results provide the missing experimental confirmation of the theoretically predicted shear instability arising from the progressive intra-band nesting of the Fermi surface with increasing pressure, a scenario common to all transition metals of group V.

http://www.nature.com/articles/srep31887