Neutron diffraction and Mdssbauer study on FeGa _x Cr_2−x S₄

Abstract

Ga doped sulphur spinel FeGa _x Cr_{2- x} S₄ (x=0.1 and 0.3) have been studied with X-ray, neutron diffraction, and Mössbauer spectroscopy. Rietveld refinement of X-ray, neutron diffraction, and Mössbauerspectroscopy lead to the conclusion that the samples are in inverse spinel type, where most Ga ions are present at octahedral site (B). The neutron diffractions on FeGa _x Cr_{2- x} S₄ (x=0.1) above 10K show long range interaction behaviors and reveal a ferrimagnetic ordering, with the magnetic moment of Fe²⁺ (−3.45 μ_B) aligned antiparallel to Cr³⁺ (+2.89 μ_B) at 10 K. Fe ions migrate from the tetrahedral (A) site to the octahedral (B) site with an increase in Ga substitutions. The electric quadrupole splittings of the A and B sites in Mössbauer spectra give direct evidence that Ga ions stimulate an asymmetric charge distribution of Fe ions in the A site.