Synthesis and Stability of Potassium/Carbonate Co-substituted Hydroxyapatites

摘要

A systematic study of the stability of potassium/carbonate co-substituted hydroxyapatite has been carried out, with samples synthesized by aqueous precipitation according to the charge-balanced mechanism: Ca_(10-x)K_x(PO_4)_(6-x)(CO_3)_x(OH)_2 Samples up to x=1.0 were prepared and their stability determined by heating at a range of temperatures in both air and CO_2 environments. Results showed that whilst samples up to x=1 .0 can be prepared phase-pure, the stability of these materials is strongly dependent on sintering temperature with the full range of compositions only being stable at 600 deg C in CO_2. The c unit cell parameter increases linearly with x, and, for a fixed composition, decreases linearly with temperature indicating loss of carbonate from the A-site. FTIR showed that samples contained carbonate at both A- and B-sites, and that carbonate content increased with x.