Abstract
Nanosized MnFe2O4 phase with diameters in the range 13.7 to 100 nm were produced by calcination and sintering treatments in the system zNb2O5 · (50 – z)MnO · 50Fe2O3 with z having values between 0 and 20. Nb5+ ions are believed to give rise to vacancies in the Mn2+ sites, which break up the coupling of ferrimagnetically active oxygen polyhedra. The Curie temperature decreases as the size of the MnFe2O4 phase is reduced. This is explained on the basis of a decrease in the number of exchange pairs of the type Mn2+–Fe3+. The coercivity increases with a decrease in the size of the ferrimagnetic phase. This is believed to arise due to a decrease in saturation magnetization as the size of the MnFeO4 phase is reduced.
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Kundu, T.K., Chakravorty, D. Nanocrystalline MnFe2O4 produced by niobium doping. Journal of Materials Research 14, 3957–3961 (1999). https://doi.org/10.1557/JMR.1999.0535
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DOI: https://doi.org/10.1557/JMR.1999.0535