Effect of MgO and Nd₂O₃ doping on the structural characteristics of nickel ferrite NiFe₂O₄

Abstract

In this work, the effect of MgO and Nd₂O₃ doping on the structural characteristics of spinel-structured nickel ferrite NiFe₂O₄ synthesized by the sol–gel auto-combustion method was investigated. The synthesized samples were subjected to thermal treatment at 1000 °C, after which their phase composition and crystal lattice parameters were examined using X-ray diffraction analysis.

It was shown that the introduction of MgO in the concentration range of 0.05–0.15 M leads to a decrease in the content of impurity phases Fe₂O₃ and FeO and, at concentrations of 0.10–0.15 M, is accompanied by the formation of a new orthorhombic Mg₂Fe₂O₅ phase characterized by enhanced structural ordering. Doping with Nd₂O₃ ensures complete suppression of impurity iron oxide phases and initiates the formation of the FeNdO₃ phase, which contributes to increased thermal and chemical stability of the spinel matrix. It was established that the combined introduction of MgO and Nd₂O₃ results in changes in the unit cell parameters of the main NiFe₂O₄ phase due to cation substitution processes and defect redistribution, as well as structural ordering of impurity phases within the nanocomposites.

The obtained results confirm the possibility of targeted control over the phase composition and structural stability of spinel-structured nickel ferrite, creating prerequisites for optimizing its functional properties and application in adsorption-based water purification processes.