| 1. |
- Jenei, István Zoltán, et al.
(författare)
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Structural phase transition in vanadium at high pressure and high temperature : Influence of nonhydrostatic conditions
- 2011
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 83:5
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Tidskriftsartikel (refereegranskat)abstract
- Vanadium has been reported to undergo phase transition upon compression from body-centered cubic (bcc) to rhombohedral structure around 62 GPa. In this paper we confirm the bcc to rhombohedral phase transition at 61.5 GPa under quasihydrostatic compression in the Ne pressure medium. Under the nonhydrostatic condition we find the phase transition occurring at 30 GPa at ambient temperature and 37 GPa at 425 K. We find the transition under the hydrostatic condition is hindered and it can occur at much lower pressure under the nonhydrostatic condition.
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| 2. |
- Landa, A., et al.
(författare)
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Ab initio calculations of elastic constants of the bcc V-Nb system at high pressures
- 2006
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Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 67:10-sep, s. 2056-2064
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Tidskriftsartikel (refereegranskat)abstract
- 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 C-44 and a corresponding softening in C at pressures similar to 2 Mbar for V. Both shear elastic constants show softening at pressures similar to 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 C-44 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.
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| 3. |
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| 4. |
- Landa, A., et al.
(författare)
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Fermi surface nesting and pre-martensitic softening in V and Nb at high pressures
- 2006
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 18:22, s. 5079-5085
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Tidskriftsartikel (refereegranskat)abstract
- First-principles total-energy calculations were performed for the trigonal shear elastic constant (C-44) of body-centred cubic (bcc) V and Nb. A mechanical instability in C44 is found for V at pressures of similar to 2 Mbar which also shows a softening in Nb at pressures of similar to 0.5 Mbar. We argue that the pressure-induced shear instability (softening) of V (Nb) is due to the intra-band nesting of the Fermi surface.
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