Vibrational Spectra of Hydrothermally Prepared Hydroxyapatites

Apatites can be used as bioceramic materials for tooth and bone implants. Infrared (4000 to 400 cm −1 ) and laser‐Raman spectra were obtained for hydrothermally prepared hydroxyapatites with the general formula X 10 (PO 4 ) 6 (OH) 2 where X= Ca 2+ Sr 2+ , Ba 2+ , or Pb 2+ Fundamental vibrational modes were identified and empirical band assignments made. Analysis of the vibrational spectra led to the reassignment of the v 2 mode to a higher wave‐number, lower‐intensity band (e.g. ∼470 cm −1 for Ca hydroxyapatite). Effects of solid‐state interaction were noted in the vibrational spectra and interpreted by factor‐group analysis. An “effective” factor group C 6h , which neglects the locations of the OH − ions, best describes the vibrational spectra of the hydroxyapatites.