Synthesis and Magnetic Properties of SrO–Fe2O3–B2O3 Glass-Ceramics

Glasses with nominal compositions of SrFe12O19 + 8SrB2O4 (I) and SrFe12O19 + 12Sr2B2O5 (II) are prepared by rapid quenching from the liquid state and are converted to glass-ceramics containing fine magnetic particles of SrFe12O19 by heat treatment between 600 and 950°C. The materials are characterized by x-ray diffraction, differential thermal analysis, electron microscopy, and magnetic measurements. The phase transformations accompanying glass crystallization are identified. The glass composition and heat-treatment conditions are shown to influence the aspect ratio of the forming submicron-sized strontium hexaferrite particles. The strongest coercive fields reached in glass-ceramics I and II are 504 and 456 kA/m, respectively.