Aging of ceramic carbonized hydroxyapatite at room temperature

The process of aging of ceramic carbonized hydroxyapatite (CHA) produced in a dry carbon dioxide atmosphere at temperatures of 800–1200$^\circ$C has been studied by chemical and X-ray structural analysis, infrared spectroscopy, and scanning electron microscopy methods. The phase composition and structure of initial prepared ceramics samples and those aged for a year have been compared. It has been shown that relaxation of internal stresses occurring during pressed sample sintering causes plastic deformation of crystallites at room temperature, accompanied by redistribution of carbonate ions between $A$1, $A$2, $B$1, and $B$2 sites and CHA decomposition with the formation of CaO separations.