Glass crystallization synthesis of ultrafine hexagonal M-type ferrites: Particle morphology and magnetic characteristics

This review concerns the synthesis and functional properties of ultrafine particles of M-type hexagonal ferrites prepared by the most advanced process of oxide glass crystallization. Hexaferrite phase formation during the heat treatment of multicomponent oxide glasses of various chemical compositions containing boron and/or silicon oxides as glass formers is considered. This route is useful to prepare assemblies of single-crystal strontium barium hexaferrite particles in the range of average particle sizes from tens of nanometers to several micrometers. The resulting glass ceramics and magnetic particle assemblies recovered from them are characterized by high coercive forces, approaching the theoretical limit for such compounds, and high magnetizations, close to the magnetization value for coarse-grained materials.