Comparison of the hydrogen uptake of different high temperature proton conductors

The water uptake of several high temperature proton conductors was studied in situ by thermogravimetry. These materials were SrCe0.95Yb0.05O3-α, SrZr0.95Yb0.05O3-α and BaCa0.39Nb0.61O3-α. At different temperatures, the weights were recorded as a function of the applied water vapour pressures. From the observed mass changes, the proton contents were calculated. For all of the three systems, the water uptake could be described by an ideal solution process. Each individual system was characterized by two parameters: 1. The solution limit which is the maximum proton concentration that can be incorporated 2. The solution enthalphy which determines the pressure and temperature dependence of the uptake. The solution limits were compared with those expected from stoichiometric considerations. The enthalphies were considered with regard to a possible application as high temperature proton conductor.