The H uptake of Ba3(Ca1.18Nb1.82)O9 was studied  in situ  by means of thermogravimetry at various temperatures and water vapor pressures. The results could be described in terms of an ideal solution process. In contrast to previous investigations of Yb-doped cerates, the present work revealed an effective O vacancy concentration which as equal to that expected on the basis of stoichiometric considerations.

F.Krug, T.Schober: Solid State Ionics, 1996, 92[3-4], 297-302