Mechanochemical synthesis and thermal evolution of La3+-ZrO2 cubic solid solutions

The formation of cubic solid solutions in the system La2O3-ZrO2 by mechanochemical activation of a mixture of the oxides (molar ratio ZrO2 82%-La2O3 18%) is studied. After 6h of activation at room temperature, a poorly crystalline cubic solid solution is formed, with ultimate crystallite sizes in the nanometer range. The mixtures activated during 1-3 h form the solid solution on subsequent heating at 1000 degreesC, while the non-activated mixture does not react, even after thermal treatment at 1200 degreesC. The solid solution obtained at room temperature undergoes partial structural ordering at temperatures between 800 and 1000 degreesC. Long time heating at temperatures of 1000degreesC and above results in the formation of La2Zr2O7 and rejection of the excess ZrO2. Mechanochemical activation offers interesting possibilities for the synthesis of these materials at temperatures lower than those used in conventional processing, and for the control of their physicochemical and microstructural properties. (C) 2004 Elsevier Ltd and Techna S.r.l. All rights reserved.