Abstract
is a high-temperature shape-memory alloy that undergoes a martensitic transformation from a parent cubic -phase into a tetragonal phase at . Measurements of the phonon dispersion curves on a single crystal show that the [110]- phonon branch, corresponding in the limit to the elastic constant has an anomalous temperature dependence. Nearly the entire branch softens with decreasing temperature as is approached. The temperature dependence of the low- phonon energies suggests that the elastic constants would approach 0 as approaches , indicating a second-order transition. No additional lattice modulation is observed in the cubic phase.
- Received 1 March 2006
DOI:https://doi.org/10.1103/PhysRevB.73.214114
©2006 American Physical Society