Quantitative Analyses of Microstructural Alterations in Multiphasic Calcium Phosphate by Micro-Raman Spectroscopy

Multiphasic calcium phosphate (CaP) composites made of hydroxyapatite (HAp), α-tricalcium phosphate (α-TCP), or β-tricalcium phosphate (β-TCP) are promising for biomedical applications. In this paper, the changes in Raman spectra of a series of HAp/α-TCP and HAp/β-TCP were calibrated and new algorithms using microRaman spectroscopy were established for an efficient and quantitative analysis of the constituent phases in multiphasic CaP systems, taking advantages of their characteristic Raman bands. The reliability of the proposed Raman algorithms was further examined and verified by the investigation of a tri-phase CaP mixture and thermally treated monolithic ceramics of HAp, α-TCP and β-TCP using both Raman and XRD analyses. The results demonstrated the applicability of the proposed method for quantitative phase evaluation, as well as higher sensitivity of Raman spectroscopy to nonstoichiometric alteration for more precise phase control and quality evaluation in the presence of defects in multiphasic CaP systems.