Electron diffraction from micro- and nanoparticles of hydroxyapatite.
Hydroxyapatite (HAP) obtained from aqueous solutions under different conditions has been examined by high-resolution transmission electron microscopy (HRTEM) and electron diffraction, including selected-area electron diffraction (SAED) and microdiffraction. A Philips CM300 field-emission gun electron microscope with a Schottky W/ZrO field-emission tip and a spherical aberration constant of 0.65 mm was used at 300 kV. The HAP crystals had different sizes, ranging from a few nanometres to a few micrometres. Single-crystal diffraction patterns have been obtained from the largest microcrystals using the conventional SAED technique. Assemblies of nanoparticles gave only broad diffuse rings. Nevertheless, microdiffraction with electron microprobes 3.5-10 nm in diameter clearly indicated the crystalline character of the nanoparticles in these assemblies. Experimental HRTEM images, Fourier transforms and calculated images exhibited the fine structure of the HAP crystals.
Suvorova
EI
Institute of Crystallography, Leninsky pr., 59, Moscow 117333, Russia.
Buffat
PA