Abstract: The quantitative phase analysis of zirconia powder treated with various temperatures and times was performed based on X-ray profile diffraction data and
Rietveld method. The results showed that zirconia powder obtained by 500℃ heat treatment for 2h was a cubic and tetragonal mixture with the weight ratio of 48:52,
whereas cubic phase disappeared in zirconia powder after 700℃ treatment for 2h and part of tetragonal phase was transformed into monoclinic phase at the same time with the
weight ratio of tetragonal to monoclinic 35:65. Almost pure monoclinic phase was obtained when zirconia powder heated at 800℃ and 900℃ for 8h and 2h respectively
and the tetragonal contents in these two cases were about 5 wt% and 1 wt% respectively. The effect of temperature and time of heat treatment on the size of grain of zirconia
powder was also discussed.

Key words: ZrO₂, quantitative analysis, Rietveld method