Sintering behavior and electrical conductivity of Ce0.9Gd0.1O1.95 powder prepared by the gel-casting process

Nanoscale Ce0.9Gd0.1O1.95 (gadolinia doped ceria, GDC) powders were prepared by a gel-casting process. Differential thermal analysis, thermogravimetry and X-ray diffraction results showed that the single-phase fluorite structure forms at a relatively low calcination temperature of 600degreesC. X-ray patterns of the GDC powders revealed that the crystallite size of the powders increases with increasing calcination temperature, which is consistent with transmission electron microscopy observations. The sintering behavior and the ionic conductivity of the cast tapes prepared from GDC powders calcined at 600-1000 degreesC were also studied. At sintering temperatures > 1450 degreesC, more than 96% of the relative density is obtained for tapes prepared from powders calcined at three different temperatures. The average grain size increases with decreasing powder calcination temperature. The alternating-current impedance spectroscopy results showed that the GDC sample sintered at 1450 degreesC has ionic conductivity of 0.046 S cm(-1) at 700 degreesC in air. The present work results have indicated that the gel-casting route is a relatively low-temperature preparation technique to synthesize GDC powders with a high sinterability and a good ionic conductivity. (C) 2002 Elsevier Science B.V. All rights reserved.