Yttrium-barium-cobalt-oxide (YBC), especially with low Y content, has
been prepared. Oxygen permeation in these materials is very high at mo
derate temperature. The materials Y0.05BaCo0.95O3-delta and Y0.10Ba0.9
0CoO3-delta consisted of a BaCoO3-delta like main phase and some minor
phases. For the Y0.05BaCo0.95O3-delta material these minor phases wer
e not exceeding 10 vol%. Y0.05BaCo0.95O3-delta had the highest oxygen
permeation value of 3.9 x 10(-7) mol/cm2 s at 900-degrees-C; the surfa
ce exchange reaction may be the rate limiting step here. The material
Y0.33Ba0.67CoO3-delta consisted mainly of two unknown cubic phases.