PREPARATION OF NANOCRYSTALLINE YSZ POWDERS BY THE PLASMA TECHNIQUE

A plasma synthesis method has been devised to produce nanosize YSZ pow ders with various yttria contents. The powders are synthesized by intr oducing a mixture of coarse-grained zirconia and yttria into an r. f. inductively coupled plasma flame. The average particle size of the as- prepared powders is in the range 20 40 nm and the specific surface are a is 18 50 m(2) g(-1). The phase and granulometric composition of the produced powders depend on the degree of evaporation of raw powders, r eagent concentration in the gas flow and quenching rate, and on the co ntent of Y2O3. Up to 5.5 mol% yttria, the major phase of nanosize powd ers is tetragonal ZrO2, mostly as the non-transformable (t') form. For yttria contents higher than 6 mol%, the major phase is cubic ZrO2. (C ) 1998 Chapman & Hall.