What are ferrox cubes and ferrites? How are mixed ferrites prepared for industrial uses? Give an account of applications of ferrites pointing out their advantages over a ferromagnetic material.
Ferrites are ceramic compounds comprising trivalent metal having three valence electrons, iron and oxide of divalent element i.e., metals having two free electrons for example MFe2O3 where M indicates transition elements like Co, Ni, Mn, divalent iron, Zn and Cu. They are majorly refractory materials in which all of the valence electrons can be considered as being tied up in an ionic bonding. They are hence unavailable for construction and unable to generate eddy currents. Eddy currents not only dissipate energy but also dampen mechanical and electrical vibrations. They hence reduce very much the usefulness of ferromagnetic materials for high frequency applications. Dielectric losses of ferrites are very low at high frequencies as they have electrical resistivity. Ferrites are thus used as ferromagnetic materials for high frequency applications like TV tubes, high-speed switches, memory devices, microwave applications, transformers. Mixing powdered oxides, compacting and sintering at elevated temperatures make them.