Size effect in X-ray and electron diffraction patterns from hydroxyapatiteparticles

High-resolution transmission electron microscopy (HRTEM), electron microdif fraction, and X-ray diffraction were used to study hydroxyapatite specimens with particle sizes from a few nanometers to several hundreds of nanometer s. Diffuse scattering (without clear reflections in transmission diffractio n patterns) or strongly broadened peaks in X-ray diffraction patterns are c haracteristic for agglomerated hydroxyapatite nanocrystals. However, HRTEM and microdiffraction showed that this cannot be considered as an indication of the amorphous state of the matter but rather as the demonstration of si ze effect and the morphological and structural features of hydroxyapatite n anocrystals. (C) 2001 MAN "Nauka/Interperiodica".