金属アルコキシドの重縮合によるY_2O_3ドープZrO_2塊状ゲルの合成と加熱変化(第2報) : 塊状ゲルの結晶化挙動と透光性ZrO_2塊状物の作製  [in Japanese] Synthesis of Y_2O_3-Doped ZrO_2 Gel Monoliths by Polycondensation of Metal Alkoxide and Their Change on Heating (Part 2) : Crystallization Behavior of Gel Monoliths and Synthesis of Translucent Y_2O_3-Doped ZrO_2 Ceramics  [in Japanese]

Monolithic Y_2O_3-doped zirconia gels were successfully prepared from zirconium alkoxide and yttrium nitrate hydrate. Crystallization behavior of these gels depended upon the concentration of Y_2O_3. Namely, ZrO_2 gel monoliths with 3 mol% Y_2O_3 or less crystallized to tetragonal phase at 400℃. On the other hand, higher concentration of Y_2O_3 resulted in the crystallization of cubic phase at 400℃. Tetragonal to monoclinic phase transformation occurred when the Y_2O_3 concentration was below 2 mol%. Doping of Y_2O_3 more than 3 mol% or 8 mol% stabilized the tetragonal or cubic phase on the further heating. The lattice parameters of the resulting tetragonal or cubic ZrO_2 showed that the Y_2O_3 concentration of the resulting ZrO_2 polycrystal was in good agreement with the batch composition. Translucent monolithic zirconia polycrystals were obtained by the careful heat-treatment of the gels up to 1000℃.