Mössbauer studies of Co xFe 1−xCr 2S 4

Abstract

The mixed spinel systems Co x Fe 1− x Cr 2S 4 has been studied using the Mössbauer effect. Spectra have been collected over the temperature range 83–300 K. The isomer shifts indicate that the charge states of Fe ions are ferrous in character throughout the series. Absence of quadrupole splitting above the magnetic ordering temperature T c suggests that iron ions occupy only tetrahedral sites. It is notable that as the temperature decreases below T c , both quadrupole shift and asymmetrical line-broadening appear and increase with decreasing temperature, suggesting the presence of electric field gradient and accompanying relaxation effects.