کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1519262 | 1511624 | 2006 | 9 صفحه PDF | دانلود رایگان |
First-principles total energy calculation based on the exact muffin-tin orbital and full-potential linear muffin-tin orbital methods were used to calculate the equation of state and shear elastic constants of bcc V, Nb, and the V95Nb05 disordered alloy as a function of pressure up to 6 Mbar. We found a mechanical instability in C44 and a corresponding softening in C′ at pressures ∼2 Mbar for V. Both shear elastic constants show softening at pressures ∼0.5 Mbar for Nb. Substitution of 5 at% of V with Nb removes the instability of V with respect to trigonal distortions in the vicinity of 2 Mbar pressure, but still leaves the softening of C44 in this pressure region. We argue that the pressure-induced shear instability (softening) of V (Nb) originates from the electronic system and can be explained by a combination of the Fermi surface nesting, electronic topological transition, and band Jahn–Teller effect.
Journal: Journal of Physics and Chemistry of Solids - Volume 67, Issues 9–10, September–October 2006, Pages 2056–2064