Effects on Phase Evolution of La2O3-ZrO2 Mixed Oxides Prepared Via Sol-Gel Process and its Crystal Growth Behavior

The nanocrystallite La2Zr2O7 were prepared via sol-gel process with glacial acetic acid (HAc) as hydrolyst and chelating agent and DMF as chemical addition in the water-ethanol solution. The influences of ethanol and glacial acetic acid on phase structure and microstructure of La2Zr2O7 nanopowders were investigated, and the corresponding crystal growth behavior of La2Zr2O7 nanocrystallite was analyzed. The results indicate that pure La2Zr2O7 with pyrochlore structure can be obtained by adjusting the content of ethanol and HAc in solution at low temperature. The mean crystallite size shows an increasing trend as the calcination temperature increases from 800 to 1300 A degrees C. Meanwhile, the effective activation energy for crystal growth in low heat-treatment temperatures (< 1000 degrees C, 13.2 +/- 0.44 kJ/mol) is much lower than that in higher heat-treatment temperatures (> 1000 degrees C, 71.0 +/- 1.16 kJ/mol).