Cation distribution in NixMg1−xFe2O4 studied by XPS and Mössbauer spectroscopy

Ni–Mg ferrites, synthesized by solid-state route, were analyzed by X-ray photoelectron spectroscopy (XPS) and Mössbauer spectroscopy to find the distribution of Mg2+ in tetrahedral (A) and octahedral (B) sites of the spinel. In NixMg1−xFe2O4, Ni2+ enters in B site resulting in a reduction in the availability of B sites for the distribution of Mg2+ and Fe3+ and thereby influences the distribution of Mg2+. It was observed through both techniques that higher percentage of Mg2+ occupied the tetrahedral sites of Ni rich spinel systems. Thermodynamic considerations showed that entropy played significant role in the distribution of Mg2+ in NixMg1−xFe2O4, in addition the difference in site preference energy between Fe3+ and Mg2+ was too small to cause any influence.