Structural and electrochemical characterization of yttrium doped barium cerate BaCe0.85Y0.15O3-α for applications in solid oxide fuel cells

G. Raikova (1) , K. Krezhov (1) , I. Genov (1) , Alain Thorel (2) , Anthony Chesnaud (2) , T. Malakova (1) , D. Vladikova (1) , Z. Stoynov (1)

1 Institute of electrochemistry and energy systems
2 CDM - Centre des Matériaux

The aim of this work is to achieve a deeper understanding of the conductivity mechanisms in BaCe0.85Y0.15O3-α (BCY15) material displaying good proton conductivity. The study is directly related to the application of BCY15 in an innovative and competitive concept for a high temperature fuel cell operated in reverse mode in the range of 600-700 °C. New approach for combining the information on atomic level by X-ray and neutron-diffraction (ND) and on macro level by impedance spectroscopy for deeper insight into the origin of its mixed (proton and oxide-ion) conductivity is applied. Single-phase BaCe0.85Y0.15O3-α samples with different porosity obtained by addition of graphite powders as pore former and changing sintering conditions were characterized in wet and dry atmosphere and their conductivity was measured in air and hydrogen in wide temperature range. The first neutron diffraction data collected at different temperatures show that the crystal structure of the samples adopts orthorhombic symmetry independently of their porosity and preparation technological conditions. Oxygen vacancies remain random at room temperature. Comparison of the proton and oxide-ion conductivity indicates that at operating temperatures (600-700 oC) they are equal. The results obtained from the electrochemical studies show that porosity of about 30-35% ensures an optimal microstructure in respect to conductivity and mechanical stability.

Keywords: Doped perovskite oxides; Neutron diffraction; Electrochemical impedance spectroscopy; Mixed ionic conductivity

Domains: Materials Science [cond-mat.mtrl-sci]

G. Raikova, K. Krezhov, I. Genov, Alain Thorel, Anthony Chesnaud, et al.. Structural and electrochemical characterization of yttrium doped barium cerate BaCe0.85Y0.15O3-α for applications in solid oxide fuel cells. Bulgarian Chemical Communications, 2017, 49 (Special issue C), pp.162-170. ⟨hal-01678037⟩