Microscopic and Macroscopic Magnetic Properties of the MgAlxCrxFe2 - 2xO4Spinel Ferrite System

To determine the influence of the substitution of Al3+ and Cr3+ for Fe3+ in MgFe2O4 ferrites on the structural and magnetic properties, the MgAl x Cr x Fe2 − 2x O4 (x = 0.0–0.8) spinel systems were studied by using the X-ray diffraction analysis, magnetization in strong fields, magnetic susceptibility in weakly variable electric fields, and Mossbauer spectroscopy. Unlike previous investigations, it was discovered that a half of Al3+ occupies tetragonal positions. The system forms a noncollinear spin structure and a central paramagnetic doublet is superimposed over the magnetic sextet in the Mossbauer spectrum (0.5 > x > 0.2). The dependence of the magnetic susceptibility on temperature reveals the normal ferromagnetic properties of the material.