Magnetic materials cubic spinel ferrites

Ferrites with the cubic spinel structure (see Section 5.3.10) are soft magnetic materials (see Section 12.4.3), widely used in electronic circuitry. The formula of all ferrites can be written as A +Fe +04, where can be chosen from a large number of medium-sized cations, for example Ni or Zn. The majority of the important ferrites are inverse spinels, in which the cations occupy the octahedral sites, together with half of the Fe + ions. The other half of the Fe cations is found in the tetrahedral sites. Thus nickel ferrite would be written (Fe +)[Ni Fe ]04, where the cations in octahedral sites are enclosed in square brackets and those in tetrahedral sites in parentheses. Lodestone, or magnetite, Fe304, described in Section 12.3.4, is an example in which the cations are Fe and Fe, and the cation distribution is (Fe +)[Fe2+Fe +]204. 

Estimate (a) the saturation magnetisation and (b) the magnetic inductance for the cubic ferrite CoFe204 with the inverse spinel stmcture. Co " " is a d ion. The cubic unit cell has a lattice parameter of 0.8443 nm and contains eight formula units. Assume that the orbital angular momentum is completely quenched in this material. 

---