Contrasting Morphology of Calcium Phosphate Powders Prepared by the Wet Method Using Poly (Ethylene Glycol)

When preparing β-tricalcium phosphate (β-TCP), it is difficult to industrialise traditional methods because of the problem of particle aggregation. In this paper, β-TCP was prepared by calcining calcium-deficient hydroxyapatite (CDHA) powders obtained by the wet precipitation method at pH=6 and 40 °C, together with additions of poly (ethylene glycol) (PEG), in order to prevent powder agglomeration. The effect of the Ca/PEG mass ratio on the particle size distribution and the morphology of the resulting powders was evaluated. For comparison purposes, one powder without PEG addition was also synthesized. All synthesized powders were characterized by means of X-ray diffraction analysis, particle size analysis and scanning electron microscopy prior and after calcination in static air at 1000 °C for 15 h. Single-phase β-TCP powders have been obtained by calcining CDHA powders in the temperature range of 850°C-1150°C. It was also found that increasing the PEG content in solution decreased the particle size distribution of the agglomerated particles and the β→α-TCP transition temperature. A plausible explanation consistent with these experimental findings is proposed.