Grain size effects on the magnetic properties of Zn_xMn_1−xFe₂O₄ nanoferrites

Single phase nanoferrites bearing the chemical formula Zn_xMn_1−xFe₂O₄ (0≤x≤1.0) have been produced under low reaction temperature of 200 °C. The compounds were characterized by X-ray diffraction, Mössbauer and SQUID measurements. The particle size varies between 5 nm and 14 nm. The particle size dependence of the magnetic properties is investigated. Our results indicate spin-glass behavior at temperatures between 100 K and 200 K. The variation of Zn concentration has also significant effects on the structural and magnetic properties. The complex variation of lattice parameter with x is explained on the basis of redistribution of Zn atoms in both tetrahedral (A) and octahedral (B) sites. The ⁵⁷Fe Mössbauer effect spectra show paramagnetic spin state in all the compounds. - Highlights: • Nanosized Zn_xMn_1−xFe₂O₄ compounds with 5.4–13.7 nm particle size synthesized and studied. • Non-linear variation of lattice constants with Zn content observed. • Spin-glass behavior inferred at intermediate temperatures (100–200 K). • Data show that magnetic behavior can be controlled through a choice of annealing conditions