Abstract: The starting powders selected for solid-state reaction to synthesize alpha-tricalcium phosphate (α-TCP) were CaHPO₄·2H₂O and CaCO₃. The effects of dispersed medium and
mineralizer CaF₂ on the synthesis of α-TCP and phase transformation were investigated. The results show that a metastable high temperature phase (α-TCP) prepared by calcining the
nonstoichiometric hydroxyapatite powder with poor crystallization obtained by grinding the mixture in distilled water is more stable than those prepared by grinding the mixture in an ethanol system. A new
and easy route, based on the solid-state reaction and the addition of CaF₂, was developed to synthesize alpha-calcium phosphate (α-TCP). For samples containing 1.0wt% and 1.5 wt% CaF₂, calcined in
the range of 1350℃ to 1450℃ and 1350℃ to 1480℃, respectively, a pure phase α-TCP was obtained. The transition energy of β-TCP to α-TCP during cooling
process is decreased by adding some mineralizer CaF₂. It will be helpful to keep the metastable high temperature phase (α-TCP) at room temperature. The stability of α-TCP in the course
of furnace cooling is also related to the content of CaF₂.

Key words: α-tricalcium phosphate, solid-state reaction, calcium fluoride, furnace cooling