in the area of physical chemistry research (for studying dy-Monodispersed nanoscale metal oxide powders are important prenamic behavior and stability of particulate systems) but also cursors for the preparation of advanced ceramics with uniform nanoin various industries. Such industries include production of structures and properties. Hydrous zirconia particles in nanometer advanced ceramics (in the form of dense ceramic monoliths, dimensions were synthesized via forced hydrolysis, that is, homogedense films, membranes, fibers, aerogels, and xerogel neous hydrolysis and controlled hydrothermal polymerization/conglasses), catalysts, sensors, superconductors, semiconductdensation of zirconium tetramers in aqueous solutions of zirconyl ing materials, engine parts, and drug-delivery systems-as inorganic salt. This thermohydrolytic route uses inexpensive starting well as chromatography packing materials, pigments, coschemicals-that is, inorganic metal salt, which makes the forcedmetics, magnetic recording particles, photographic emulhydrolysis approach more competitive than other sol-gel routes using metal alkoxides. Hydrothermal treatment of zirconyl salt solutions sions, and many others (1, 2). In particular, nanometer-(0.01 to 0.075 M) produced nanocrystalline monoclinic ZrO 2 powder size particles/clusters are the constituent grains (or building with a narrow size distribution. The hydrous zirconium oxide particles blocks, typically from 1 to 100 nm in diameter) of materials are somewhat porous, cube-shaped aggregates of small crystallites (รต such as nanophase ceramics, which are considered one of 5 nm). The nucleation and nanoparticle growth in zirconyl chloride the frontiers of research in ceramics science. By controlling aqueous solutions (100ะC) was successfully monitored with a customthe size of the nanoparticles, the mechanical, optical, chemidesigned, low-power dynamic laser light-scattering spectrophotomecal, electrical, and magnetic properties of the nanophase mater. Extensive experimental evidence strongly supports the position terials can be dramatically improved and, thus, tailored to that particle growth is mainly via an aggregation mechanism. On the meet specific needs (3). Monodispersity is preferred to enother hand, the growth kinetics are controlled by the coupled events hance densification and grain growth in ceramics. However, involving polymerization/condensation and colloidal coagulation.
synthesis methods are needed for production of monodis-Both the controlled-reaction and the controlled-aggregation approaches were studied to reduce the induction period for nucleation persed nanoparticles.
as well as to enhance particle growth kinetics. The present study of Ultrafine zirconia (ZrO 2 ) particles are of particular interthe synthesis process and the characterization of nanosize powders est in this work because of their potential use in the fabricaconstitute prerequisite steps for fabrication of dense, nanophase zircotion of dense nanocrystalline zirconia ceramics that have a nia materials (with grain size on the order of 1 to 100 nm) that unique set of properties: high refractoriness and corrosion are expected to have improved mechanical and thermomechanical resistance, mechanical strength and fracture toughness, and stability at elevated temperatures.