The mixed perovskites BaCa(1+x)/3Nb(2-x)/3O3-x/2 (x = O ... 0.18): proton uptake

The mixed perovskites BaCa(1+x)/3Nb(2-x)/3O3-x/2 were investigated for x = 0, 0.06, 0.12 and 0.18. The latter compound is the widely studied ceramic B CN18 which has served as a prototypical high temperature proton conductor i n recent years. The ceramics with x = 0.06 and 0.12 show a much lower solub ility for water vapor. A linear increase in lattice parameter was observed when going from x = 0 to 0.18. Density measurements supported the model of vacancies on the O-sublattice in the dry state. The volume of such a vacanc y is close to that required by an O-atom. (C) 2000 Elsevier Science B.V. Al l rights reserved.