Ultraporous Submicron-Grained β-Ca3(PO4)2-Based Ceramics.

β-Tricalcium phosphate (β-Ca3(PO4)2) based ceramics with a relative density of 20–21%, grain size from 200 to 600 nm, and compressive strength from 1.6 to 1.8 MPa have been produced by 1000°C firing of cement stone prepared from a powder mixture having a Ca/P molar ratio of 1.5 and consisting of hydroxyapatite (Ca10(PO4)6(OH)2), calcium citrate tetrahydrate (Ca3(C6H5O7)2·4H2O), and calcium dihydrogen phosphate monohydrate (Ca(H2PO4)2·H2O). The mixing liquid used to initiate chemical binding reaction in the powder mixture was distilled water. The phase composition of the cement stone included brushite (CaHPO4·2H2O) and unreacted starting materials. The presence of platelike calcium pyrophosphate (Ca2P2O7) particles, formed from platelike brushite (CaHPO4·2H2O) particles, impeded densification of the ceramics during firing and ensured the formation of an ultraporous structure. The submicron-grained microstructure and phase composition of the β-Ca3(PO4)2-based ceramics resulted mainly from heterophase interactions between the products of thermal decomposition of cement stone components. Offering sufficient strength, biocompatible and bioresorbable ultraporous submicron-grained β-Ca3(PO4)2-based ceramics can be recommended for use in regenerative medicine for bone tissue defect repair. [ABSTRACT FROM AUTHOR]