VIBRATIONAL SPECTROSCOPIC STUDY OF TETRACALCIUM PHOSPHATE IN PURE POLYCRYSTALLINE FORM AND AS A CONSTITUENT OF A SELF-SETTING BONE-CEMENT

Polycrystalline tetracalcium phosphate (TTCP), a material of considera ble interest for human implantation due to its similarity to hydroxyap atite, was studied by means of Raman and FT-LR spectroscopy. The spect ra were interpreted on the basis of group theoretical considerations. In addition, the setting reaction of a calcium phosphate cement (CPC) consisting of an equimolar mixture of TTCP and dicalcium phosphate (DC PA) was investigated by Raman spectroscopy The band of the totally sym metric phosphate mode nu(1) of TTCP showed marked factor group splitti ngs. The splitting components arose at coincident wave numbers in the IR and Raman spectra. This observation was in accordance with space gr oup P2(1) (factor group C-2(2), Z = 4). The characteristic splitting o f nu(1) allowed the setting reaction of CPC to hydroxyapatite to be fo llowed. According to the Raman spectroscopic results, considerable amo unts of TTCP must be present at the sample surface after 24 h of setti ng in an aqueous environment. (C) 1998 John Wiley & Sons, Inc.