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

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 $s$-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.