PROPERTIES OF SOL-GEL DERIVED Al2O3-15 WT% ZrO2 (3 MOL% Y2O3) NANOPOWDERS USING TWO DIFFERENT PRECURSORS

Alumina-15 wt% zirconia (3 mol% yttria) nanopowders were synthesised by a sol-gel method using salt and alkoxide as precursors. Al(NO3)3.9H2O, ZrOCl2.8H2O and Y(NO3)3.6H2O were used as the salt precursors and Al(OC4H9)3 and Zr(OC4H9)4 were used as alkoxide precursors. The dried gels of the two precursors were heat treated at 450-1350 C. The powders produced by the alkoxide precursors calcined at 750 C had a particle size in the range 15-75 nm, while those prepared by salt precursors had a particle size in the range 30-90 nm. The former powders had a higher surface area and smaller mean pore diameter compared with the latter powders, i.e. 152 m2/g and 5.63 nm compared with 121 m2/g and 9.79 nm, respectively. The phase transformation in the former occurred at lower temperatures.