The thermal decomposition of Mg-containing carbonate apatites

Carbonate apatites precipitated from an aqueous solution and containing Mg²⁺ and Sr²⁺ ion were studied by thermogravimetric, infrared absorption, and X-ray diffraction methods. In the temperature range of 25-350°C water evolves and at 350-905°C carbonate decomposes. Two effects characterize the Mg-containing system: Weight loss during decomposition is related to carbonate in the apatite and to an additional ion; increased formation of whitlockite. The interrelation between these two phenomena and the presence of carbonate and Mg is discussed.