Electronic structure of the sigma-phase in paramagnetic Fe-V alloys. Experimental and theoretical study

TL;DR

This study combines experimental and theoretical methods to analyze the electronic structure of sigma-phase Fe-V alloys, revealing site-specific charge densities and electric field gradients, and successfully interpreting Mössbauer spectra.

Contribution

It provides the first determination of charge densities and electric field gradients at nonequivalent Fe sites in sigma-phase Fe-V alloys, integrating calculations with experimental spectra analysis.

Findings

Charge densities vary across different Fe sites.

Electric field gradients differ among lattice sites.

The combined approach successfully explains Mössbauer spectra.

Abstract

The electronic structure of $\sigma$-phase Fe$_{100-x}$V$_x$ compounds with 33.3 $\le x \le 60.0$ was calculated from the charge self-consistent Korringa-Kohn-Rostoker method. For the first time, charge densities $\rho_A(0)$ and electric field gradients were determined at Fe nuclei, that occupy five nonequivalent lattice sites. The highest $\rho_A(0)$ values were found on sites A and D, and the lowest one on site B, the difference ranging between 0.162 and 0.174 $\it s$-like electrons per Fe atom for $x = 33.3$ and $x = 60$, respectively. The calculated quantities combined with experimentally determined site occupancies were successfully applied to analyze $^{57}$Fe M\"ossbauer spectra recorded on a series of 8 samples in a paramagnetic state.