SYNTHESIS OF YTTRIA-STABILIZED ZIRCONIA NANOPARTICLES BY DECOMPOSITION OF METAL NITRATES COATED ON CARBON POWDER

Weakly agglomerated nanoparticles of yttria-stabilized zirconia (YSZ) were synthesized by a novel process which involved the decomposition o f metal nitrates that had been coated on ultrafine carbon black powder , after which the carbon black was gasified. The use of ultrafine, hig h-surface-area carbon black powder apparently allowed the nanocrystall ine oxide particles to form and remain separate from each other, after which the carbon black was gasified at a somewhat higher temperature. As a result, the degree of agglomeration was shown to be relatively l ow. The average crystallite size and the specific surface area of the as-synthesized YSZ nanoparticles were 5-6 nm and 130 m(2)/g, respectiv ely, for powder synthesized at 650 degrees C. The as-synthesized YSZ n anoparticles had a light brown color and were translucent, which diffe rs distinctly from conventional YSZ particles which are typically whit e and opaque. The mechanism of the synthesis process was investigated, and indicated that the gasification temperature had a direct effect o n the crystallite size of the as-synthesized YSZ nanoparticles. High-d ensity and ultrafine-grained YSZ ceramic articles were prepared by fas t-firing, using a dwell temperature of 1250 degrees C and a dwell time of two minutes or less.