Electrochemical impedance spectroscopy of BaCeO3 modified by Ti and Y

Barium cerate exhibits high protonic conductivity, especially when modified by trivalent dopant such as Y, Yb, Nd, Sm or Dy. Unfortunately, the poor chemical stability in the presence of CO₂ is the main disadvantage of this material. One of the possible approach to get the stable protonic conductor is the preparation of solid solutions. For example, doping of BaCeO₃ with Zr leads to the improvement of the chemical stability, but the electrical properties are simultaneously corrupted.In the present work the influence of Ti, per analogy to Zr, and Y dopants on electrical properties of BaCeO₃ was investigated using the electrochemical impedance spectroscopy (EIS) technique. BaCe_1−xTi_xO_3−δ (0 ≤ x ≤ 0.3) and Ba(Ce_0.95Ti_0.05)_0.95Y_0.05O_3−δ solid electrolytes were prepared by solid-state reaction method. It was found that the changes of electrical properties due to the introduction of Ti into the BaCeO₃ lattice is caused predominantly by the modification of the grain boundary properties. The Ti doping leads to the substantial decrease of grain boundary electrical conductivity, comparing to undoped material. The introduction of yttrium dopant to the BaCe_0.95Ti_0.05O₃ lattice has the opposite effect. The total electrical conductivity increases, due to significant modification of grain boundary electrical properties.