Ca3PO42

Ca3(PO4)2, commonly known as tricalcium phosphate (TCP), is a calcium salt of phosphoric acid with a calcium-to-phosphate ratio of 3:2. It exists in several polymorphs, notably alpha-TCP and beta-TCP, which differ in crystal structure and stability. In water, TCP is sparingly soluble and tends to transform into other calcium phosphate phases over time, especially under acidic or hydrolytic conditions.

TCP can be prepared by precipitation from solutions containing calcium and phosphate ions, and is widely produced for industrial and medical uses. It is a white, odorless powder that is insoluble in water and reacts with acids. Because of its bioactivity, TCP is used as a bone graft substitute and in dental cements, where it can set and gradually remodel into bone mineral. It is also employed as a dietary calcium and phosphate supplement and, in some jurisdictions, as a food additive for fortification and anticaking purposes.

Related calcium phosphate materials include hydroxyapatite (Ca5(PO4)3OH), brushite (CaHPO4·2H2O), monetite (CaHPO4), and octacalcium phosphate (Ca8(HPO4)2(PO4)4·5H2O). The usefulness of TCP in biomedical applications stems from its resorbability and osteoconductivity, allowing it to support bone ingrowth while dissolving to release calcium and phosphate ions.

Safety and handling: TCP is generally regarded as having low toxicity and is relatively insoluble in neutral conditions. Excessive ingestion or exposure to acidic environments can increase solubility and affect mineral balance, so standard handling precautions apply in industrial and clinical settings.