Colloidal Processing and Ionic Conductivity of Fine‐Grained Cupric‐Oxide‐Doped Tetragonal Zirconia

CuO‐doped tetragonal ZrO 2 (3‐mol%‐Y 2 O 3 ‐doped tetragonal zirconia, 3Y‐TZ) green bodies were consolidated from zirconia slurries with Cu 2+ by a pressure filtration method. The slurries were prepared by dispersing 3Y‐TZ powder in a solution of [NH 4 OH + NH 3 NO 3 ] = 0.1 M at pH 11 and adding an appropriate amount of Cu(NO 3 )·3H 2 O solution. Green bodies with narrow pore‐size distribution were obtained after cold isostatically pressing the pressure‐filtrated bodies. Small amounts of CuO‐doped samples were densified fully at 1200°C. The size of a grain of 0.16‐mol%‐CuO‐doped 3Y‐TZ sintered at 1200°C was 84 nm. Bulk and grain‐boundary conductivities are measured by a complex impedance method. The bulk conductivity of the CuO‐doped 3Y‐TZ was almost equal to the undoped one, but the grain‐boundary conductivity decreased with CuO addition.