Structural stability of calcium phosphate cement during aging in water

A calcium phosphate cement (CPC) has been prepared by mixing dicalcium phosphate anhydrate (DCPA, CaHPO4) and calcium hydroxide (Ca(OH)2) with a sodium phosphate (Na2HPO4) solution. After setting and hardening, the cement is aged in water. High resolution structural and microstructure analyses are carried out to evaluate the stability of the CPC in water over a period of 150 days. The lattice parameters of the apatite crystal remain the same throughout the aging process. The size of apatite crystallites is not changed either; nevertheless, the shape of the particles changes from equiaxed to rod-like.