Thermal decomposition of carbonated calcium phosphate apatites

The thermal stability of AB-type carbonated calcium phosphate apatites prepared by precipitation from aqueous media was studied. The behavior of powders was investigated using temperature programmed XRD, infrared spectroscopy and thermogravimetry. In N-2 atmosphere, two successive peaks of decarbonatation with maxima at about 700 and 950 degreesC occurred. This behavior is explained by different substitution modes for carbonates in the apatite. The decarbonatation peaks were shifted to higher temperature under CO2 (around 900 and 1150 degreesC). The analysis of the thermal stability allowed further densification of carbonate apatite ceramics without important carbonate loss.