The Relation Between The Elastic And Electronic Structure Properties Of Niobium Under Ultrahigh Pressures
Lugovskoy A. V. 1, Tal A. A.1,2, Mosyagin I. Yu. 1,2 Ponomareva A. V. 1 , Abrikosov I. A. 1,2
1 NUST MISIS, Materials Modeling and Development Laboratory, Moscow, Russia
2 Linköpings University, IFM, Linköping, Sweden
The focus of this work are the effects of electronic structure on the elastic properties of solids at ultrahigh pressures. It is known, that electronic topological transitions, which take place under extreme compressions are responsible for many unique effects. We chose niobium as the object of study, since the transition metals are the usual material for samples in groundbreaking experimental works in the field of static high pressure techniques. At the same time the 5-th group transition metals (V, Nb, Ta) demonstrate an outstanding combination of properties as well as interesting behavior under pressure. For example, vanadium is known to have phase transition to low symmetry phase at the pressure of ~70 GPa. The presence of electronic topological transition in both vanadium and niobium are well known from the literature, at the same time, intense studies are usually only dedicated to the former.
We present qualitatively new picture of the relation of electronic structure and elastic properties in pure niobium. Careful ab initio calculations were performed to figure out the impact of electronic topological transition (ETT) on the character of stress-strain relations in the material. A peculiarity of the elastic properties of Nb is clearly observed in the pressure range of 0-100 GPa. The range of strains in which the Hook’s low holds is shrinking upon the approach to the ETT at high pressure, and effectively vanishes at the ETT. The role of the electronic structure modification upon deformation in this effect can be clearly distinguished. The mechanism of this subtle, but explicilty observed relation is discussed. The fundamental nature of the phenomena points on the possibility of such effects in other metallic systems.