57Fe M�ssbauer, Infrared and X-Ray Studies of the System Zn1?xCuxCr0.8Fe1.2O4

Spectral studies of the cubic spinel ferrites Zn1—xCuxCr0.8Fe1.2O4, 0 ≤ x ≤ 1 are carried out at room temperature by X-ray, Mössbauer and IR spectra. The deduced X-ray parameters have been studied as functions of x. The average and true lattice parameters (ā and a0), the theoretical and bulk densities (DX and D), and the porosity P were determined for all samples. The positional oxygen parameter u, the tetrahedral and octahedral ionic radii (rA and rB), the tetrahedral and octahedral bond lengths (dAX and dBX), the tetrahedral and shared and unshared octahedral edges (dAE, dBE and dBEU), have been calculated and deduced. It has been found that ā decreases and DX increases with x ≤ 0.6 and the opposite behaviour takes place with x > 0.6. Except x = 0, D decreases and P increases with x. The parameters a0, u, rA, dAX, dAE and dBEU decrease with x while rB, dBX and dBE increase. The room temperature Mössbauer spectra showed that the samples with x ≤ 0.6 are paramagnetic while the samples with x > 0.6 are ferrimagnetic. The determined hyperfine interaction parameters as functions of x have been studied and discussed. The cation distributions have been determined. The infrared studies confirmed the presence of four peaks. These peaks were ν1, ν2, ν3 and ν4 and assigned to the tetrahedral A-site, octahedral B-sites, divalent ions at B-sites and lattice vibrations, respectively.