Search for the electronic phase transition in NiTi

Soft x-ray appearance potential spectroscopy was used to search for evidence of the electronic phase change in NiTi which has been proposed by Mitchell, Wang, and Cullen. No such evidence was found. Any temperature-dependent changes in the filling of the d band or in the s-band–to–d-band ratio are at least an order of magnitude less than predicted by the proposed model. Electron transfer between Ni and Ti atoms accompanies changes in stoichiometry but is not characteristic of the NiTi II–to–NiTi III phase transition.