Phase equilibria in the tricalcium phosphate-mixed calcium sodium (potassium) phosphate systems

• Published in: Russian journal of inorganic chemistry Vol. 59; no. 11; pp. 1219 - 1227
• Main Authors: Evdokimov, P. V., Putlyaev, V. I., Ivanov, V. K., Garshev, A. P., Shatalova, T. B., Orlov, N. K., Klimashina, E. S., Safronova, T. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.11.2014
• Subjects: Apatite; Calcium phosphate; Channels; Chemistry; Chemistry and Materials Science; Inorganic Chemistry; Invariants; Phase equilibria; Phase transformations; Sodium; Solid solutions; Synthesis and Properties of Inorganic Compounds; High Temperature Phase; TRICALCIUM Phosphate; Unit Cell Parameter; Differential Thermal Analysis; Phosphorite
• ISSN: 0036-0236; 1531-8613
• DOI: 10.1134/S0036023614110084

Phase equilibria in the quasi-binary sections Ca 3 (PO 4 ) 2 -CaMPO 4 (M = Na, K) are distinguished by high-temperature isomorphism of glaserite-like phases α’-Ca 3 (PO 4 ) 2 and α-CaMPO 4 . The main differences of the Ca 3 (PO 4 ) 2 -CaKPO 4 system from the Ca 3 (PO 4 ) 2 -CaNaPO 4 system are a shift of invariant equilibria toward higher temperatures, deceleration of phase transformations, and the emergence of polymorphism of an intermediate phase of an ordered solid solution based on α-CaKPO 4 . The low-temperature modification of this phase of a composition near Ca 8 K 2 (PO 4 ) 6 has the apatite structure with unoccupied hexagonal channels.