Synthesis Of (ZrO₂)_1-x(RE₂O₃)_x(RE=Sm,Yb) And Electrical Properties Of Their Sinters

(ZrO₂)_1-x (RE₂O₃) _x(RE = Sm , Yb) nanocrystallites with a cubic phase were hydrothermally prepared in basic media. For comparison (ZrO₂)_0.91 (Yb₂O₃)_0.09 was syntheized by sol-gel method. It is discovered that the cubic-phased nanocrystallite size is obviously affected by pH value, temperature and time of hydrothermal reaction. Green compacts made from the nanopowders can be sintered to above 97% of theoretical density at 1450 ℃, which is about 150 ℃ lower than that for traditional high temperature(>1600 ℃) solid state reaction. The oxygen ion conduction properties of ceramics were investigated by means of complex impedance, oxygen concentration cell, oxygen pump (electrochemical oxygen permeation) and fuel cell at 600 1000 ℃. The results show that these sinters are almost pure oxygen conductors with oxide-ionic transport number of 1 in oxygen concentration cell over the temperature range of 600 1000 ℃. Only the pump based on (ZrO₂)_0.86(Sm₂O₃)_0.14 ceramic (the hydrothermal conditions: pH = 11.61, 150℃ , 48h) show the equal electrochemical oxygen permeation rates of the observe value and the theoretical value at 600 1000 ℃. But the other ceramics only above 800℃ show the equal values of oxygen pump, whereas below 800 ℃ the observe value was lower than the theoretical value.(ZrO₂)_0.91 (Yb₂O₃)_0.09 prepared by sol-gel method had as higher oxide-ion transport number as hydrothermally prepared, but the fuel cell performance was better than the sinter prepared by hydrothermal reaction.