Structural and Magnetic Properties of (Mg0.8Fe2+0.2)(Al0.4CrxFe3+1.6−x)O4 Spinel Solid Solution Obtained by Molten Salt Synthesis

(Mg0.8Fe2+0.2)(Al0.4CrxFe3+1.6−x)O4 (x = 0.0, 0.4, 0.8, 1.2, and 1.6) spinel particles are prepared by molten salt method at 1050 °C for 5 h. The solid solution structure is determined by X‐ray diffraction (XRD) as cubic spinel with Fd‐3m space group. The lattice parameter and crystalline size decrease with increasing Cr content. Cr3+ ions occupy the octahedral sites, as shown by combined Fourier transform infrared spectroscopy (FTIR) and XRD analysis. The magnetization as a function of field (±4.52 T) and field‐cooled (FC) and zero‐field‐cooled (ZFC) magnetization measurements under a field of 100 Oe is measured for temperatures ranging from 1.5 to 300 K. It is found from M(T) curves that the interparticle interactions are suppressed below 28.1–40.8 K, and the curves also shows the ferromagnetic from M(H) hysteresis for the samples with x = 0.0, 0.4, and 0.8. However, for x = 1.2 and 1.6, the samples show superparamagnetic, as also supported by the obtained electron paramagnetic resonance (EPR) and Mössbauer spectra. (Mg0.8Fe2+0.2)(Al0.4CrxFe3+1.6−x)O4 particles are prepared by molten salt method. A single‐phase spinel solid solution is formed for x = 0.0–1.2. The lattice constant and particle size decrease with increasing chromium content. Interparticle interactions are suppressed below 28.1–40.8 K, and the samples show ferromagnetic behavior for x = 0.0, 0.4, 0.8, while superparamagnetic for x = 1.2, 1.6.