Synthesis of ZrSiO₄ powders by a sol-gel method with varied calcination temperatures

The effect of calcination temperature on phase formation of the powders prepared with starting materials ZrCL₄ and TEOS (tetraethylorthosilicate) was studied. Stoichiometric Zr/Si (1:1 mol%) mixture of samples were prepared by a sol-gel method after 5 wt.% of PVA (polyvinyl alcohol) addition as a catalyst and mechanical activation via ball milling for 5 h. The mixtures were then calcined at 900, 1000, 1100, 1200, and 1300 °C for 10 h. The phase composition was determined by Rietveld analysis of X-ray diffraction (XRD) data using Rietica software. Results showed that at calcination temperatures of 900, 1000, and 1100 °C, only tetragonal zirconia was observed, but retained silica in an amorphous state. Both phases then completely reacted to form zircon at 1200 °C. At 1300 °C, a little amount of zircon decomposed into tetragonal zirconia and cristobalite. (paper)