The infrared and Raman spectra of β- and α-tricalcium phosphate (Ca3(PO4)2)

Factor group analysis was applied to interpret the vibrational spectra of beta- and alpha- tricalcium phosphate (Ca-3(PO4)(2)). The analysis predicts the number of bands formed due to the splitting of the fundamental vibrational modes of the PO43- ion. The number of the infrared and Raman bands predicted by this analysis for the two phases are drastically different and can be ascribed to the difference in atomic arrangements in the two phases resulting in greater shielding of the PO43- ions in the beta- phase than in the alpha- phase. Discrepancies in the number of predicted and experimentally-observed bands can be attributed to the weak intensities of some vibrational modes or the convolution of vibrations and limited spectral resolution.