Zirconia nanopowder was successfully prepared using sugar and citric acid by a precursor calcination process, in which sugar was used as a gelling agent and citric acid as a catalyst. The effect of citric acid on this zirconia preparation is found out by the variable time of addition of citric acid on the preparation, namely SZG (before sugar) and SGZ (after sugar). The calcinations were conducted at 600οC and 800οC. XRD results show that at 600οC, t- and m-ZrO2 phases are identified in SZG, whereas t-ZrO2 is the only phase in SGZ. XRD analysis finds that both of the zirconia samples having had crystallites below 20 nm. At a high temperature of 800 ο C, two phases of zirconia are identified as t- and m-ZrO2 in both of the samples with different intensities. A Quanta FEG SEM study shows both of the zirconia samples at 800 ο C have homogenous microstructures and grain sizes less than 100 nm. A high resolution sophisticated SEM investigation shows that the SZG sample at 800 ο C has an average grain size below 50 nm. However, the effect of the citric acid addition time on the zirconia preparation is clearly visible in the zirconia phase transformation. The earlier addition of citric acid on the preparation gives two phases of zirconia in the final product at 600 ο C; and by contrast, the later addition of the acid after sugar on the preparation produces only t-ZrO2 phase.

Keywords: Nanopowder, Zirconia, Preparation, Precursor process, Sugar, Citric acid.