Cation distribution and crystallographic characterization of the quaternary spinel system Mg xCo 1− xCr xFe 2− xO 4

Abstract

Quaternary spinel compound Mg x Co 1− x Cr x Fe 2− x O 4 ( x = 0.0, 0.25, 0.50, 0.75 and 1.0) was synthesized in the solid state sintering method. Neutron powder diffraction measurements at room temperature were performed on the materials. Rietveld refinement of the neutron powder diffraction data was done for determining the cation distribution and crystallographic characterization of the system. The refinement yielded a mixed cationic distribution with Co, Fe and Mg being distributed over tetrahedral and octahedral sites in varying proportions while Cr was found to uniquely occupy the octahedral interstices. Increase of tetrahedral bond distance and decrease of octahedral bond distance with x was also revealed from the refinement. Sublattice and net magnetic moments at room temperature were also deduced from the refinement of room temperature neutron diffraction data.