Са$_{3}$(РО$_{4}$)$_{2}$ polymorphism

The present article is devoted to the $\beta\to\alpha$ phase transformation of Са$_{3}$(РО$_{4})$. This phase transformation is low-rate, first-order reconstructive transition, $\alpha$-Са$_{3}$(РО$_{4}$)$_{2}$ can be obtained in the course of low-rate cooling (ca. 5$^\circ$С/min). Transformation $\alpha\to\alpha$' is a high-rate, first-order deformation phase transition; such a fact indicates that $\alpha$'-Са$_{3}$(РО$_{4}$)$_{2}$ cannot be obtained even by quenching.