Influence of Cr substitution on Debye-Waller factor and related structural parameters of ZnFe_2-xCr_xO₄spinels

The influence of Cr³⁺ions on the Debye-Waller factor and other related structural parameters of the polycrystalline ZnFe_2-xCr_xO₄(0.0 ≤ x ≤ 2.0) system was characterized at room temperature using the XRD, TEM, SEM and infrared (FT-IR) spectroscopy tools. X-ray diffraction results confirm the FCC spinel structure. Values of the lattice constant ‘a’ were found to decrease from 8.4370 Å for ZnFe₂O₄ferrites to 8.3208 Å for ZnCr₂O₄chromates. The structure factors for the (hkl) planes were calculated and used to estimate the intensity of the X-ray diffractions and the cation distributions among the tetrahedral and octahedral sites. The Debye-Waller factors were used to estimate the Debye effective temperatures, the mean square displacements and Debye frequencies of these spinels. The FT-IR spectra were characterized by two main absorption bands υ₁and υ₂in the frequency range of (400–1000) cm⁻¹. These bands are caused by stretching vibrations at the tetrahedral (A) and octahedral (B) sites respectively. The scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs revealed aggregates of stacked grains.