Enthalpy of Formation and Mixing of Calcium-Cadmium Phosphoapatites
2004 年 15 巻 p. 113-118
詳細
2004 年 15 巻 p. 113-118
Calcium-Cadmium phosphoapatites solid solutions with formula Ca 10-x,Cdx,(PO4)6Y2 where Y is OH, F, or Cl were synthesized and characterized by infrared spectroscopy, X Ray diffraction and chemical analysis. Using an isoperibol calorimeter the enthalpies of solution of these products in nitric acid 9 weight % have been determined. Thermochemical cycles were proposed to acess to the enthalpies of formation and mixing. The results show an increase in the enthalpy of formation with the quantity of cadmium introduced in the lattice. The variations of the enthalpy of solution and the enthalpy of mixing versus Cd/(Ca+Cd) atomic ratio were correlated to the existence of two sites in the apatitic structure.
