(ZrO₂)_0.86(Sm₂O₃)_0.14 and (ZrO₂)_0.88(Sm₂O₃)_0.12 nano-powders were hydrothermally prepared in basic media by co-precipitation of Zr(OH)₄ and Sm(OH)₃. Green compacts made with the nano-powders prepared hydrothermally could be sintered to above 98% of theoretical density at 1450 ℃, which was 150 ℃ lower than that (＞1600 ℃) used for traditional high-temperature solid state reaction. The results of XRD indicated that both the nano-powders and sinter of (ZrO₂)_0.86(Sm₂O₃)_0.14 are in a cubic phase, and (ZrO₂)_0.88(Sm₂O₃)_0.12 nano-powder is in a cubic phase, but its sinter is in a mixed phase of cubic phase and monoclinic phase. The oxygen ion conduction properties of (ZrO₂)_0.86(Sm₂O₃)_0.14 ceramic were investigated by means of complex impedance, oxygen concentration cell and oxygen pump (electrochemical oxygen permeation) at 600～1000 ℃. The maximal conductivity of the ceramic is 3.2×10^－2 S•cm^－1 in O₂ at 1000 ℃. The conduction in the ceramic is purely oxide-ionic with oxygen ion transference number of 1 over the whole temperature range of 600～1000 ℃. This ceramic is obviously superior to YSZ ceramic in oxygen pump performance.

Key words: (ZrO₂)_0.86(Sm₂O₃)_0.14, nano-powder, solid-electrolyte, hydrothermal synthesis, SOFC