Quantitative determination of amorphous content in bioceramic hydroxyapatite (HAP) using X-ray powder diffraction data

Calcium hydroxyapatite (HAP), a bioceramic for clinical application, was prepared by a wet chemical method. Biodegradation of such materials increases with the amorphous content. The parameters involved in the method of preparation were varied and subsequently a standard material was obtained. Rapid estimation of low amorphous content in crystalline matrices was done by applying the X-ray diffraction technique. Here the classification of the crystalline and amorphous X-ray scattering has been made by comparison of the slopes at two successive points of the intensity pattern over scattering angles where both crystalline and amorphous phases superimpose. If the second slope exceeds the first by a stipulated value, the intensity is deemed as crystalline, otherwise the scattering is considered as amorphous. The amount of glass content is within 6% ± 1%. The method of X-ray diffraction technique has unique features and is consequently easy to apply to any composite system. The results obtainable are fairly accurate.