Anomalous variation of electric field gradient in α-Ti

Abstract

Variation of electric field gradient (EFG) at ¹⁸¹Ta occupying substitutional sites in α-Ti matrix has been studied in the temperature interval from 10 to 300 K using time differential perturbed angular correlation spectroscopy. Among the main sources of EFG such as conduction electrons and lattice ions, the present study shows that in α-Ti, the temperature dependence of EFG is predominantly due to conduction electrons. The variation of EFG could not be fitted with either as the linear dependence of temperature (T) or T^3/2 over the whole temperature interval 10-300 K. Existence of two different slopes with a change of slope occurring around 150 K is observed while the EFG is fitted with T or T^3/2. The above change of slopes of EFG in α-Ti, which is understood to be due to a slight modification in conduction electron-phonon interactions based on this work, is possibly caused by the electronic topological transitions below 150 K as has been reported.