The influence of calcium to phosphate ratio on the nucleation and crystallization of apatite glass-ceramics.
The nucleation and crystallization behavior of a series of glasses based on 4.5SiO2-3Al2O3-YP2O5-3CaO-1.51CaF2 was studied. The parameter Y was varied to give calcium to phosphate ratios between one and two. All of the glasses studied crystallized firstly to fluorapatite (Ca5PO4)3F). The glass with a calcium to phosphate ratio of 1.67, corresponding to apatite, bulk nucleated to give fluorapatite (FAP). The glasses with calcium : phosphate ratios either less than that of apatite, or greater than that of apatite all exhibited surface nucleation of FAP. However, following a nucleation hold of one hour at approximately 50 K above the glass transition temperature these glasses exhibited bulk nucleation of FAP.
Clifford
A
A
Department of Materials Science and Technology, University of Limerick, Limerick, Ireland.
Hill
R
R
Rafferty
A
A
Mooney
P
P
Wood
D
D
Samuneva
B
B
Matsuya
S
S