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

Abstract

The compositional dependence of structural parameters and X-ray Debye temperature for CuAl x Fe 2− x O 4 ( 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 Al 3+-substitution has marked influence on various parameters. A deficit of Cu 2+-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.