AN ESR STUDY OF DEFECTS IN IRRADIATED HYDROXYAPATITE

Radiation-induced defects in synthetic hydroxyapatite (HAp) of six dif ferent origins have been investigated by electron spin resonance (ESR) , X-ray diffraction (XRD), Raman scattering and IR measurements. The o rthorhombic CO2- radicals were detected in almost of all the samples e xamined, but the isotropic CO2- was produced only in water-containing HAp with low crystallinity. The doublet signal due to H-0 was clearly detected in HAp with extreme calcium deficiency as compared to the sto ichiometry. The results of ESR and FTIR suggest that water molecules i n low crystalline HAp are not on the surface but embedded in the HAp c rystalline lattice. Copyright (C) 1996 Elsevier Science Ltd