Crystallization of a SrO-B
2O
3-SiO
2-Fe
2O
3 glass was investigated to elucidate the precipitation process of SrFe
12O
19 from the glass matrix.
The results obtained are as follows; an unidentified crystal phase, X-phase, precipitates by heating the glass in the temperature range from
Tg (546°C) to 750°C. The X-ray diffraction lines of the X-phase are well indexed with assuming a cubic unit cell with α=7.584Å. In the temperature range from 650°C to 750°C, 4SrO⋅B
2O
3⋅SiO
2 precipitates in the vicinity of the glass surface and gradually grows toward the inside of the glass.
SrFe
12O
19 co-precipitates with 4SrO⋅B
2O
3⋅SiO
2 in the temperature range from 750°C to 850°C. 4SrO⋅B
2O
3⋅SiO
2 has crystallized rapidly in the whole region of the glass and no X-phase is observed in that temperature range. The amount of SrFe
12O
19 with heating time changes relatively in the same manner as that of 4SrO⋅B
2O
3⋅SiO
2. Based on these results, hexagonal platelets of SrFe
12O
19 with a dimension of%cong; 0.3μm are obtained as a precipitate from the glass by the heat-treatment at 800°C for 5 hr.
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