Bioceramics Based on β-Calcium Pyrophosphate

Ceramic samples based on β-calcium pyrophosphate β-Ca(2)P(2)O(7) were prepared from powders of γ-calcium pyrophosphate γ-Ca(2)P(2)O(7) with preset molar ratios Ca/P = 1, 0.975 and 0.95 using firing at 900, 1000, and 1100 °C. Calcium lactate pentahydrate Ca(C(3)H(5)O(3))(2)⋅5H(2)O and monocalcium phosphate monohydrate Ca(H(2)PO(4))(2)⋅H(2)O were treated in an aqua medium in mechanical activation conditions to prepare powder mixtures with preset molar ratios Ca/P containing calcium hydrophosphates with Ca/P = 1 (precursors of calcium pyrophosphate Ca(2)P(2)O(7)). These powder mixtures containing calcium hydrophosphates with Ca/P = 1 and non-reacted starting salts were heat-treated at 600 °C after drying and disaggregation in acetone. Phase composition of all powder mixtures after heat treatment at 600 °C was presented by γ-calcium pyrophosphate γ-Ca(2)P(2)O(7) according to the XRD data. The addition of more excess of monocalcium phosphate monohydrate Ca(H(2)PO(4))(2)·H(2)O (with appropriate molar ratio of Ca/P = 1) to the mixture of starting components resulted in lower dimensions of γ-calcium pyrophosphate (γ-Ca(2)P(2)O(7)) individual particles. The grain size of ceramics increased both with the growth in firing temperature and with decreasing molar ratio Ca/P of powder mixtures. Calcium polyphosphate (t (melt) = 984 °C), formed from monocalcium phosphate monohydrate Ca(H(2)PO(4))(2)⋅H(2)O, acted similar to a liquid phase sintering additive. It was confirmed by tests in vitro that prepared ceramic materials with preset molar ratios Ca/P = 1, 0.975, and 0.95 and phase composition presented by β-calcium pyrophosphate β-Ca(2)P(2)O(7) were biocompatible and could maintain bone cells proliferation.