FTIR AND RAMAN-SPECTRA OF BIOCERAMICS OBTAINED BY AN INNOVATIVE METHOD

Bioceramic coatings with defined chemical composition and structure ar e often needed to satisfy specific biocompatibility properties in the prosthetic field. An example is hydroxyapatite (HA) for coatings, whic h, according to the Standard Specifications of the ASTM, must be cryst alline and have a stoichiometric molar ratio Ca/P=1.67 with a 95% mini mum amount of HA. Since the methods (plasma flame spray, ion beam sput tering, etc.) to obtain bioceramic coatings, in particular those for H A, induce changes in the chemical composition, structure and physical state of the coating, an alternative and innovative method (the so-cal led polymeric route) which provides bioceramic coatings under less sev ere conditions with controlled chemical composition and structure, was used in this work. The method was applied to the preparation not only of HA, but also, for the first time, of high-temperature-melting calc ium phosphate bioactive glasses with a molar ratio CaO/P2O5=1 (calcium metaphosphate) and in the range 1-1.5 (calcium oligophosphates). The different phases of the process were characterized by vibrational FTIR spectra. The structure of the final glasses were a Iso stud led by Ra man spectroscopy and com pared with the spectra of the same products o btained by the traditional melting method.