PHASE-SEPARATION IN BA-FERRITE GLASS-CERAMICS INVESTIGATED BY FARADAYMICROSCOPY

The crystalline phase precipitation in the glass crystallization of M- type Ba-hexaferrite fine particles is investigated by means of Faraday microscopy. The experimental method using a magneto-optical garnet se nsor film which converts the magnetic stray field distribution at the sample surface into a luminance distribution in the recorded image is described. By combination with X-ray diffractometry, magnetization mea surements and scanning electron microscopy including EDX-microprobe an alysis the phase constitution of glass ceramics prepared in different ways is determined. It is shown that the precipitation of fine crystal line particles of different phases is influenced by inhomogeneous inte rnal stress in the glass matrix which is either related to the crystal lization process in a self-generating manner or may be induced by mech anical crushing of the starting glass phase.