Influence of vanadium on the ${}_{}{}^{57}{}_{}{}^{}\mathrm{site}$ spin and charge densities in cobalt-vanadium alloys

The influence of substitutional vanadium on spin and charge densities has been studied for a series of hcp ${\mathrm{Co}}_{100\mathrm{-}\mathrm{x}}$${\mathrm{V}}_{\mathrm{x}}$ alloys with x≤12.5, using ${}_{}{}^{57}{}_{}{}^{}\mathrm{site}$ Mössbauer spectroscopy. It has been shown that one V atom residing in the first-neighbor shell reduces the ${}_{}{}^{57}{}_{}{}^{}\mathrm{site}$ hyperfine field by Δ$H_1$=38.4 kOe and the isomer shift by Δ$I_1$=0.020 mm/s which means an increase of the charge density by Δ$N_1^s$=0.01 s electrons. The influence of one V atom as a second-nearest neighbor is similar in sign but three times smaller in magnitude. The maximum change of the charge density (i.e., that due to three V atoms per unit cell) which can be evaluated from the correlation between the average hyperfine field and the average isomer shift amounts to η=0.03–0.05 s electrons. The results are compared with those obtained for the bcc Fe-V system.