Samples in the system BaCe1-xInxO3-alpha were prepared in a concentrat
ion range 0.05 mole less than or equal to x less than or equal to 0.25
mole InO1.5 and the physical-chemical properties determined. The maxi
mum doping level is 0.20 mole InO1.5 in BaCeO3 for which almost single
phase products were obtained. The doped barium cerates correspond wit
h the structure of BaCeO3 with a small amount of CeO2. The compounds a
re stable in reducing and oxidizing atmospheres and have a high solubi
lity of oxygen. The In-doped BaCeO3 shows a point defect behaviour in
the oxygen pressure range from 1 bar to 10(-6) bar. The highest total
electrical conductivity was observed for a content of 0.20 mole InO1.5
in BaCeO3. It is influenced by the water vapour partial pressure in r
educing and inert gases in the temperature range from 700 degrees C to
1000 degrees C. The electrical conductivity of In-doped BaCeO3 does n
ot exceed the conductivity of yttria-stabilized zirconia and not even
that of the brownmillerite-structure oxides Ba2In2-xCexO5. The mean io
nic transport number is (t) over bar(ion) = 1 in hydrogen between 630
degrees C and about 800 degrees C whereas above 800 degrees C a deviat
ion from 1 is detected. In argon larger deviations from 1 are observed
in the whole temperature range. (C) 1998 Elsevier Science B.V. All ri
ghts reserved.