Characteristics of crystals precipitated in sintered apatite/wollastonite glass ceramics

In this paper, apatite/wollastonite (A/W) glass ceramics were obtained by s intering the A/W glass powder compact at 1200 degrees C. XRD, TEM and EDX w ere used to identify the crystalline phase and determine the chemical compo sition. The results showed that, the precipitated crystals at 1200 degrees C were wollastonite and whitlockite. The sintered A/W glass ceramics consis ted of crystalline phases, while glass matrix was found on the grain bounda ry. Whitlockite crystal showed a hexagonal morphology, while wollastonite e xhibited a column shape. The two crystals were non-stoichiometic, and certa in amounts of Mg and Si were found in wollastonite and whitlockite. The exi stence of Si in whitlockite caused an increment in lattice volume while Mg did not change the lattice parameter of wollastonite due to different ion r adius. (C) 2000 Elsevier Science Ltd and Techna S.r.l. All rights reserved.