Crystal structure and functional properties of Nd1.6Ca0.4Ni1-yCuyO4+δ as prospective cathode materials for intermediate temperature solid oxide fuel cells

• Published in: International journal of hydrogen energy 2021-05, Vol.46 (32), p.17037-17050
• Main Authors: Filonova, E.A., Pikalova, E.Yu, Maksimchuk, T.Yu, Vylkov, A.I., Pikalov, S.M., Maignan, A.
• Format: Article
• Language: English
• Subjects: Cathode material; Chemical compatibility; Electroconductivity; Oxygen electrode; Ruddlesden-Popper phase; Thermal expansion
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2020.10.243

Complex oxides Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0–0.4) have been prepared by a pyrolysis of glycerol-nitrate compositions. According to the X-ray diffraction analysis, the materials are single-phase up to y = 0.3 and crystallize in an orthorhombic structure (Bmab) at room temperature. High-temperature studies assert that they all undergo a phase transition from orthorhombic to tetragonal (I4/mmm) structure in a range of 300–400 °C. With Cu doping, the over-stoichiometric oxygen content δ decreases from 0.07 (y = 0.0) down to 0.00 (y = 0.3). The studies on the compact samples reveal the maximum value of total conductivity (165 S cm−1 at 420 °C) and the minimum value of the linear coefficient of thermal expansion (11.9·10−6 K−1 in a range of 400–1000 °C in air) at y = 0.2. Chemical compatibility of the Nd1.6Cа0.4Ni1-yCuyO4+δ (y = 0.0, 0.2) oxides with oxygen- and proton conducting electrolytes (Ce0.9Gd0.1O1.95, Ce0.8Sm0.2O1.9 and BaCe0.5Zr0.3Y0.1Yb0.1O3-δ) up to a temperature of 1100 °C is demonstrated. [Display omitted] •Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0–0.3) are orthorhombic single phases.•Temperature increasing promotes phase transition to tetragonal structure.•Cu-doping leads to oxygen content decreasing and to electroconductivity increasing.•Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0; 0.2) are compatible with some chosen electrolytes.