Sintering behavior of in situ cobalt oxide-doped cerium-gadolinium oxide prepared by flame spray pyrolysis

Ce0.9Gd0.1O1.95 (CGO10) and in situ cobalt oxide-doped CGO10 were prepared by pilot-scale flame spray synthesis, yielding powders with an average particle size of 40 nm. Cobalt oxide was shown to be a very effective sintering aid for CGO10 and lowered the maximum sintering temperature from 1450 degrees to about 1200 degrees C. Sintering studies revealed that in situ cobalt oxide-doped CGO10 exhibited a temperature of maximum shrinkage rate of 880 degrees C for a dopant concentration of 1 mol% CoO1-x, whereas for conventionally cobalt oxide-doped CGO10, this temperature was 914 degrees C. This decrease is believed to be a result of a more homogeneous dopant distribution of the in situ cobalt oxide-doped CGO nanopowders as compared with the powders in which the doping was introduced as nitrates.