Structure induced tunable magnetic properties of Zn substituted Mn1−xZnxFe2O4(x= 0–1) NPs

Abstract

Mn1−xZnxFe2O4 nanoparticles (MZ NPs) owing to their Zn content dependent tunable magnetic properties have potential applications in energy conversion devices and in nanomedicine. It is a well-recognised fact that magnetism of MZ NPs has critical dependence on degree of Zn substitution at tetrahedral sites. In addition, the role of cation distribution between the tetrahedral and octahedral sites for a particular degree of Zn-substitution, i.e. the degree of inversion (δ) also influences their magnetic characteristics. However, the exact correlation between distribution of bivalent metal ions between tetrahedral and octahedral sites and corresponding magnetic characteristics is not well understood. In order to explore this structural dependence of magnetic characteristics of MZ NPs, a series of Mn1−x Zn x Fe2O4 (x = 0−1) nanoparticles have been synthesized by chemical co-precipitation method. Saturation magnetisation and Curie temperature of MZ NPs are strongly correlated with the degree of inversion and exchange interactions between the magnetic ions, while the coercivity and remanence is independent of it and only depends on crystallite size. Both saturation magnetisation and Curie temperature decreases with increasing Zn substitution into spinel matrix. This could be attributed to the weakening of strong (A-B) inter lattice super exchange interaction instead partial substitution of Zn at octahedral Mn sites.