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. Author manuscript; available in PMC: 2009 Jan 14.
Published in final edited form as: Analyst. 2008 Feb 1;133(3):302–318. doi: 10.1039/b716791a

Table 3.

Some properties of hydroxyapatite and its precursors (adapted from refs 63-66)

Type of BCP Formula Molar ratio Ca : P P content of crystals/mmol g-1 Solubility product constant, Ksp Calcium conc. at equilibrium/mol
Hydroxyapatite (HA) Ca10(PO4)6(OH)2
= Ca5(PO4)3OH
= 3Ca3(PO4)2·Ca(OH)2 		1.67 : 1 5970 2.34 × 10-59 4.36 × 10-7
Tricalcium phosphate Ca3(PO4)2 1.50 : 1 6450 2.83 × 10-30 1.45 × 10-6
Octacalcium phosphate Ca8(HPO4)2(PO4)4·5H2O
= Ca4H(PO4)3·3H20		 1.33 : 1 6000 2.00 × 10-49 1.08 × 10-6