The nucleation and crystallization of a series of glasses based on 4.5SiO(2
).3Al(2)O(3).1.5P(2)O(5).(5 - z)CaO.zCaF(2) with a Ca:P ratio corresponding
to apatite were studied. In these glasses, the objective was to investigat
e the influence of fluorine content and z was varied from 3 to 0. All the g
lasses studied crystallized to fluorapatite (FAP) and mullite with the exce
ption of the glass containing no fluorine, which crystallized to P-tricalci
um phosphate (Ca-3(PO4)(2)) and anorthite (CaAl2Si2O8). Glasses that contai
ned sufficient fluorine to form FAP bulk nucleated to give FAP without a nu
cleation hold. Thermal gravimetric analysis demonstrated a significant weig
ht loss corresponding to the crystallization of mullite, which increased wi
th the fluorine content of the glass and also with decreased particle size.
The loss was attributed to volatile SiF4. The glass transition temperature
decreased with increased fluorine content of the glass.