Density Functional Study of the L10-alphaIrV Transition in IrV and RhV
Abstract
Both IrV and RhV crystallize in the alpha IrV structure, with a transition to the higher symmetry L1(sub 0) structure at high temperature, or with the addition of excess Ir or Rh. Here we present evidence that this transition is driven by the lowering of the electronic density of states at the Fermi level of the IrV structure. The transition has long been thought to be second order, with a simple doubling of the L1(SUB 0) unit cell due to an unstable phonon at the R point (0 1/2 1/2). We use first-principles calculations to show that all phonons at the R point are, in fact, stable, but do find a region of reciprocal space where the L1(sub 0) structure has unstable (imaginary frequency) phonons. We use the frozen phonon method to examine two of these modes, relaxing the structures associated with the unstable phonon modes to obtain new structures which are lower in energy than L1(sub 0) but still above IrV. We examine the phonon spectra of these structures as well, looking for instabilities, and find further instabilities, and more relaxed structures, all of which have energies above the alpha IrV phase.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 03, 2010
- Accession Number
- ADA522829
Entities
People
- Gus L. Hart
- Michael J. Mehl
- Stefano Curtarolo
Organizations
- United States Naval Research Laboratory