Structural parameters and X-ray Debye temperature determination study on copper-ferrite-aluminates

The compositional dependence of structural parameters and X-ray Debye temperature for CuAlxFe2-xO4 (x = 0.0, 0.2, 0.4 and 0.6) spinel ferrite system has been studied by means of X-ray powder diffraction (XRD) patterns analysis at 300 K. The XRD data have been used to determine the lattice constant, X-ray density, distribution of cations among the tetrahedral and octahedral sites of spinel lattice, oxygen positional parameter, site radii, bond angle, bond length and interionic distances. The X-ray Debye temperatures have been determined from integrated intensities of selected Bragg reflections. It is found that Al3+-substitution has marked influence on various parameters. A deficit of Cu2+-cations at the octahedral sites of the spinel lattice leads to the absence of co-operative active Jahn-Teller distortion and the crystal structure retains into cubic. The increasing disagreement between observed and calculated intensities and reduction in intensity of diffracted beam with increasing Al-concentration have been explained based on preferred orientation and extinction effects. The effect of oxygen deficiency on intensity ratios of planes has been discussed in brief. (C) 2010 Elsevier Masson SAS. All rights reserved.