Synthesis and magnetic properties of SrO-Fe2O3-B2O3 glass-ceramics

Glasses with nominal compositions of SrFe12O19 + 8SrB(2)O(4) (I) and SrFe12O19 + 12Sr(2)B(2)O(5) (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 950degreesC. 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.