NANOMETRIC POWDERS AND SINTERED CERAMICS STUDIED BY ATOMIC-FORCE MICROSCOPY

Atomic force microscopy, as well as the Brunauer, Emmett, and Teller t echnique and x-ray diffraction, was used to analyze ultrafine NiZn fer rite powders hydrothermally synthesized at 200 degrees C, for 5 h. The particle sizes, measured through AFM images acquired from the surface of pressed powders, were 52 +/- 6 nm, which were higher than those ob tained by the other techniques. The particles were monodispersed in si ze and approximately spherical, meeting the requirements for the produ ction of high density sintered components. The observations performed on ceramic bodies sintered at different conditions (1100-1400 degrees C, 5 to 240 min) showed necks characteristic of the early stages of si ntering (1100 degrees C) and the expected pore curvature evolution (14 00 degrees C) with sintering time in the final stage of the sintering process. Using a straightforward sample preparation technique, AFM pro ved to be a powerful tool for direct analysis of ceramic powder partic les on the nanometric scale and sintered ceramics at different sinteri ng stages.