Characteristics of crystals precipitated in sintered apatite/wollastonite glass ceramics

In this paper, apatite/wollastonite (A/W) glass ceramics were obtained by sintering the A/W glass powder compact at 1200°C. XRD, TEM and EDX were used to identify the crystalline phase and determine the chemical composition. The results showed that, the precipitated crystals at 1200°C were wollastonite and whitlockite. The sintered A/W glass ceramics consisted of crystalline phases, while glass matrix was found on the grain boundary. Whitlockite crystal showed a hexagonal morphology, while wollastonite exhibited a column shape. The two crystals were non-stoichiometic, and certain amounts of Mg and Si were found in wollastonite and whitlockite. The existence of Si in whitlockite caused an increment in lattice volume while Mg did not change the lattice parameter of wollastonite due to different ion radius.