Effect of Microwave Processing on Polycrystalline Hard Barium Hexaferrite

The present paper describes our results on the phase transformation (from crystalline to amorphous) of M- type hard barium hexaferrite, and consequently its conver- sion into soft ferrite by the application of magnetic energy at microwave frequency (2.45 GHz). The rapid volumetric heating of the conventionally prepared polycrystalline hexa- ferrite by microwave energy at a temperature of 950 °C in a short duration of only 5 min resulted in a decrystallized phase. The magnetic studies (M–H loops) of the resistively heated and MW processed samples have revealed a lower- ing in coercivity (from 188 to 2 mT) in the latter samples, thereby establishing the formation of soft ferrite. An attempt has also been made to understand the observed transformation from hard to soft ferrite