Inelastic neutron scattering studies of synthetic calcium phosphates

Infrared and Raman spectra have been used extensively for the characterisat ion of the mineral component of mineralised tissues, especially bone and te eth. Often the vibrational modes of hydroxy groups and hydrogen phosphate a re masked in the presence of substituent anions such as carbonate. The inel astic neutron scattering (INS) spectra are dominated by the vibrations of g roups with hydrogen or with hydrogen riding on groups. Two sets of bands ha ve been assigned to the hydroxy librations related to the hexagonal and mon oclinic polymorphs of hydroxyapatite. Of the phosphate bands in brushite on ly the HPO42- bands are seen in the INS spectrum. These INS studies of synt hetic hydroxyapatites and brushite present new opportunities for studying a spects of biominerals not accessible by standard vibrational techniques.