On the Debye temperature in sigma-phase Fe-V alloys

TL;DR

This study investigates the Debye temperature in sigma-phase Fe-V alloys using neutron, X-ray, and Mossbauer spectroscopy, revealing non-monotonic behavior with composition and providing first-ever data on T_D in these alloys.

Contribution

It is the first study to report the Debye temperature in sigma-phase Fe-V alloys, combining multiple techniques to analyze structural and vibrational properties.

Findings

Debye temperature varies non-monotonically with composition

Lattice parameters increase linearly with V content

Maximum T_D of 600K observed at x=59

Abstract

A series of sigma-phase Fe_{100-x}V_x samples with 34.4 < x < 59.0 were investigated by neutron and X-ray diffraction and Mossbauer spectroscopy (MS) techniques. The first two methods were used for verification of the transformation from alpha to sigma phase and they also permitted to determine lattice parameters of the unit cell. With MS the Debye temperature, T_D, was evaluated from the temperature dependence of the centre shift, <CS>, assuming its entire temperature dependence originates from the second-order Doppler shift. To our best knowledge, it is the first ever-reported study on T_D in sigma-FeV alloys. Both attice parameters i.e. a and c were revealed to linearly increase with x. T_D shows, however, a non-monotonic behaviour as a function of composition with its extreme values between 425K for x=40 and 600K for x=59. A local maximum of 525K was found to exist at x=43.