Electronic structure of the martensitic phases B19'-NiTi and B19-PdTi

Abstract

Self-consistent LAPW band structure calculations were performed for the martensitic phases B19'-NiTi and B19-PdTi. The resulting densities of states (DOS), partial charges, partial densities of states, electron densities and Fermi surfaces were compared to the results of a former calculation for B2-NiTi and B2-PdTi. The DOS at the Fermi level is lower for the martensitic than for the austenitic phases. The most significant changes at the phase transition were found for the Fermi surfaces and derived properties. Nesting between electron and hole sheets of the Fermi surface is greatly reduced in the martensites. The generalized susceptibility and the function zeta (q) approximating the electron-phonon contribution to the dynamical matrix were also calculated for three symmetry directions. Maxima of zeta (q) show up only in the (111) direction. Furthermore, calculated XPS spectra and optical conductivities were compared to experiment, if available.