Engineering Physics

7.10 Ferrimagnetic substances [Ferrites]

In ferrimagnetic crystals, the magnetization of two sublattices occurs as the one in anti-ferromagnetic crystals but of unequal magnitudes, which results a non-zero value. The ferrimagnetic crystals consist of two or more different kinds of atoms. Chemically, they are expressed as M_e⁺⁺ Fe₂⁺⁺⁺ O₄⁻⁻, where M_e⁺⁺ stands for a suitable divalent metal ion such as Fe⁺⁺, Co⁺⁺, Ni⁺⁺, Mg⁺⁺, Mn⁺⁺, Zn⁺⁺, Cd⁺⁺, etc. The Fe₂⁺⁺⁺ is a trivalent ferric ion. If we insert Ni⁺⁺ for Me⁺⁺, then the compound would be called as nickel ferrite, if Fe⁺⁺ is inserted for Me⁺⁺, then the compound is ferrous ferrite, written as Fe⁺⁺ Fe₂⁺⁺⁺ O₄⁻⁻ or in more familiar form as Fe₃ O₄.

X-ray crystallography reveals that usually ferrite oxygens ...