NMR investigations of ion distribution in real structure of manganese-zinc ferrites

Using the nuclear magnetic resonance, X-ray and electromagnetic methods we investigated structure and properties of the single- and polycrystalline manganous and manganese-zinc ferrites: MnFe₂O₄, Mn_0.8Zn_0.2Fe₂O₄, Mn_0.6−xCu_xZn_0.3Fe_2.1O₄ (0 ≤x ≤ 0.3). The real structure of the manganous and manganese-zinc ferrites is found to contain simultaneously vacancies in cationic and anionic sublattices. The analysis of the NMR spectra of⁵⁵Mn,⁵⁷Fe,^63,65Cu and⁶⁷Zn ions allowed us to find the magnetic and valence states of all ions and their distribution in the real spinel structure. It was shown that the Fe³⁺ paramagnetic ions, Zn²⁺ diamagnetic ions and cationic vacancies in tetrapositions are distributed statistically. The Mn³⁺ and Cu²⁺ Jahn-Teller ions and presumably Fe²⁺ in octahedral positions are distributed nonstatistically forming cluster-type mesoscopic inhomogeneities. The correlation between distribution of ions and vacancies in the real structure of manganese-zinc ferrites and their functional electromagnetic properties was found.