Dielectric Properties of Fine Particles of Fe₃O₄ and Some Ferrites

Abstract

A study is made on the dispersions of resistivity and dielectric constant of α-Fe 2 O 3 , γ-Fe 2 O 3 , Fe 3 O 4 , Zn ferrite, Mn ferrite, and MnZn ferrite fine particles over the frequency range of 10 Hz to 1 MHz in the temperature range from 77°K to 300°K. The Maxwell-Wagner interfacial polarization arising from the heterogeneity of oxidation is observed in the fine particles of the oxides, except α-Fe 3 O 3 , which are prepared from aqueous solutions of divalent metal salts as well as in the powders of ferrites containing ferrous ions which are prepared by the calcination at high temperatures. The structures of heterogeneity in the fine particles are explained by the model that there are high resistivity shells with poor ferrous ions on the surfaces of the particles.