The influence of Y and Gd co-doping on the structure, microstructure, and electrical conductivity of BaCeO3-BaZrO3 protonic conductors

BaCeO 3 is a well-known ceramic proton-conducting material with high electrical conductivity. Unfortunately, the thermodynamic instability of this material in the atmosphere containing CO 2 and H 2 O is still a problem, and numerous studies have focused on improving the chemical stability by partially substituting Ce with Zr in the BaCeO 3 lattice. However, the introduction of Zr impacts the high grain boundary resistivity which directly affects the electrical conductivity of the system. On the contrary, introducing a trivalent dopant such as yttrium or gadolinium helps create the oxygen vacancy and enhance the electrical properties of the material This research aimed to investigate the structure, microstructure, and electrical properties of co-doped materials by yttrium and gadolinium in the solid solution BaCeO 3 - BaZrO 3 . The Y and Gd co-doped BaCe 0.6-x Zr 0.3-y Y 0.1 Gd (x,y) O 3-ẟ (x,y=0, 0.1, 0.2) powder samples were synthesised using the solid-state method then compacted into pellets and free sintered. Detailed structural and microstructural investigations and analyses were conducted. The electrical conductivities of the samples were tested in dry air, wet air, and 5 vol% H 2 in Ar at temperatures ranging from 200°C to 740°C. The influence of dopants on electrical properties was discussed in relation to microstructure and crystal structure modifications. • the Y and Gd co-doped BaCe 0.6-x Zr 0.3-y Y 0.1 Gd x+y O 3-ẟ (x,y=0, 0.1, 0.2) samples were successfully synthesized • the influence of yttrium and gadolinium co-doping of the BaCeO 3 - BaZrO 3 solid solution on the structure, microstructure, and electrical properties was investigated • the electrical conductivity is mostly influenced by the crystal structure type, but the microstructure modification should be also considered