Acceptor doping effects on microstructure, thermal and electrical properties of proton-conducting BaCe0.5Zr0.3Ln0.2O3−δ (Ln = Yb, Gd, Sm, Nd, La or Y) ceramics for solid oxide fuel cell applications

It is found that: (i) the mean grain size grows (from 1.4 to 3.8 μm), (ii) the thermal expansion coefficient increases (from 7.6·10−6 to 11.3·10−6 K−1 in the high-temperature range), (iii) the ionic conductivity decreases (from 10.2 to 0.3 mS cm−1 at 800 °C) with increasing ionic radius of acceptor Ln-dopant. It is also found that BaCe0.5Zr0.3Y0.2O3−δ electrolyte can be considered as the most optimal one for IT-SOFC applications from the view point of electrical properties. However, in the temperature interval of 550-700 °C, this sample possesses nonlinear thermal expansion.