LOW-TEMPERATURE PREPARATION OF NANOSTRUCTURED ZIRCONIA AND YSZ BY SOL-GEL PROCESSING

Stable zirconia sol, with a particle size sharply monodispersed at 4 nm, was synthesized via hydrolysis of zirconia tetra-n-butoxide in 2-propanol. Stable composite sols were prepared via an ''interparticle'' modification route by introducing yttrium nitrate. Although the nanostructure of the dried gels was insensitive to yttrium addition, the crystallization behaviour was greatly influenced by it. Without yttrium addition the monoclinic zirconia was obtained at 700 K. After ''interparticle'' modification with yttrium, the cubic phase of yttria-stabilized zirconia was directly obtained at 726 K. The sintering of both the systems was also enhanced at low temperature. As a result of the low-temperature processing, nanostructured zirconia and YSZ with homogeneous grain sizes of a few tens of nanometres have been successfully prepared.