Highly dense and chemically stable proton conducting electrolyte sintered at 1200 °C

• Published in: International journal of hydrogen energy Vol. 43; no. 2; pp. 894 - 907
• Main Authors: Hossain, Shahzad, Abdalla, Abdalla M., Radenahmad, Nikdalila, Zakaria, A.K.M., Zaini, Juliana H., Rahman, S.M. Habibur, Eriksson, Sten G., Irvine, John T.S., Azad, Abul K.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2018
• Subjects: Chemical stability; Electrolyte; Impedance analysis; Perovskite; Proton conductor; Rietveld refinement; Perovskite; Rietveld refinement; Electrolyte; Proton conductor; Chemical stability; Impedance analysis
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2017.11.111

The BaCe0.7Zr0.1Y0.2−xZnxO3−δ (x = 0.05, 0.10, 0.15, 0.20) has been synthesized by the conventional solid state reaction method for application in protonic solid oxide fuel cell. The phase purity and lattice parameters of the materials have been studied by the room temperature X-ray diffraction (XRD). Scanning electron microscopy (SEM) has been done for check the morphology and grain growth of the samples. The chemical and mechanical stabilities have been done using thermogravimetric analysis (TGA) in pure CO2 environment and thermomechanical analysis (TMA) in Argon atmosphere. The XRD of the materials show the orthorhombic crystal symmetry with Pbnm space group. The SEM images of the pellets show that the samples sintered at 1200 °C are highly dense. The XRD after TGA in CO2 and thermal expansion measurements confirm the stability. The particles of the samples are in micrometer ranges and increasing Zn content decreases the size. The conductivity measurements have been done in 5% H2 with Ar in dry and wet atmospheres. All the materials show high proton conductivity in the intermediate temperature range (400–700 °C). The maximum proton conductivity was found to be 1.0 × 10−2 S cm−1 at 700 °C in wet atmosphere for x = 0.10. From our study, 10 wt % of Zn seems to be optimum at the B-site of the perovskite structure. All the properties studied here suggest it can be a promising candidate of electrolyte for IT-SOFCs.
Rietveld analysis confirms that BaCe0.7Zr0.1Y0.2−xZnxO3−δ (x = 0.05, 0.10, 0.15, 0.20) crystallized in the orthorhombic symmetry after sintering at 1200 °C which are highly dense and good protonic conductors. Insert shows the schematic 3D diagram (left) and high density SEM profile (right). [Display omitted]
•The materials were in single phase orthorhombic structure at 1200 °C.•Highly dense at 1200 °C and large SEM morphology for IT-SOFC electrolyte.•High chemical stability up to 1000 °C under carbon dioxide.•It shows high conductivity of 1.0 × 10−2 S cm−1 at 700 °C in wet H2.