Structural Studies of the Spinel System GaxCoFe1-xCrO4 (0 ≤ x ≤ 1) by Neutron Powder Diffraction
Solid solutions of GaxCoFe1-xCrO4 ( x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were obtained by solid state reactions in air at 1623K. X-ray and neutron powder diffraction measurements have been performed on the materials in order to characterize them. Rietveld refinement of neutron powder diffraction data showed cubic symmetry corresponding to the space group Fd-3m for all of the samples in the series. The results reveal that Ga has been substituted for Fe selectively. Ga exclusively occupies the octahedral site up to x = 0.8, while at x =1.0 a small amount of Ga (5%)enters into the tetrahedral site in the compound. Cr, Fe and Co cations are distributed between the tetrahedral 8 a and octahedral 16 d sites. Their proportion at each site varies with composition. The fractional coordinates of oxygen are almost the same in all the samples while the lattice parameter shows a slight decrease with increasing Ga content. The magnetic structure at room temperature was ferrimagnetic for the composition x = 0.0 and x = 0.2.
Yvonne Andersson, Eric J. Mittemeijer and Udo Welzel
A.K. Azad et al., "Structural Studies of the Spinel System GaxCoFe1-xCrO4 (0 ≤ x ≤ 1) by Neutron Powder Diffraction", Materials Science Forum, Vols. 443-444, pp. 325-328, 2004