Atomic force microscopy study of silica nanopowder compacts

Nanometer silica powders compacted at different pressures have been studied by atomic force microscopy (AFM). Local elastic moduli measurements made o n the powder compacts yield values smaller than that of bulk silica. Loadin g force-distance curves measured show break points at some critical pressur es. AFM images obtained at constant contact forces above and below the crit ical force at which a break point occured show the break point was a result of AFM tip plowing into the nanometer powder compacts. The applied force r equired for break points to occur increases with sample density. Such a beh avior has been qualitatively explained in terms of adhesion force between n anoparticle and sample surface morphology. (C) 1999 Kluwer Academic Publish ers.