Thermo-physical insights into a series of strontium substituted hydroxyapatite

Abstract

In this study, we investigated the effect of Sr substitution (2, 4, 8, 16 mol. %) on the thermo-physical properties of hydroxyapatite (HA). FTIR and Raman analysis revealed that Sr substitution incorporated CO32 and HPO42 into the HA lattice and consequently SrHA lost more mass according to the TG studies. The substitution of Sr reduced the dehydroxylation peak temperatures from 1266 degrees C to 1226 degrees C and decomposition peak temperatures from 1472 degrees C to 1432 degrees C. Heat treated HA, 2SrHA, 4SrHA and 8SrHA preserved dominant HA phase (>99%). However, 16SrHA decomposed to TCP (>23 wt %). Moreover, Sr substitution increased the a and c lattice constants and thus, enlarging the crystal volume of HA. Raman studies confirmed that Sr substituted HAs up to 8 mol % decomposed slightly to oxyhydroxyapatite (OHA). We employed a deconvolution process to the Raman peaks at similar to 960 cm(-1) to calculate the degree of the OHA decomposition by Sr substitution.