Journal of the American Ceramic Society, Vol.88, No.10, 2942-2944, 2005
Direct calorimetric measurement of enthalpies of phase transitions at 2000 degrees-2400 degrees C in yttria and zirconia
High-temperature differential thermal analysis provided data on phase transitions in zirconia and yttria. The tetragonal form of ZrO2 transforms to the cubic fluorite structure at 2311 degrees +/- 15 degrees C with an enthalpy of 3.4 +/- 3.1 kJ/mol. Cubic C-type Y2O3 transforms, probably to the fluorite structure, at 2308 degrees +/- 15 degrees C with Delta H = 47.7 +/- 3.0 kJ/mol. This high-temperature polymorph melts at 2382 degrees +/- 15 degrees C with an enthalpy of fusion of 35.6 +/- 3.0 kJ/mol.