Structure and Dynamics Investigations of Sr/Ca-Doped LaPO4 Proton Conductors

• Published in: Journal of physical chemistry. C 2017-06, Vol.121 (22), p.11991-12002
• Main Authors: al-Wahish, Amal, al-Binni, U, Tetard, L, Bridges, C. A, Kharel, Krishna, Günaydın-Şen, Özge, Huq, A, Musfeldt, J. L, Paranthaman, M. P, Mandrus, D
• Format: Article
• Language: English
• Subjects: INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.7b02254

Proton conductors loom out of the pool of candidate materials with great potential to boost hydrogen alternatives to fossil-based resources for energy. Acceptor-doped lanthanum orthophosphates are considered for solid oxide fuel cells (SOFCs) for their potential stability and conductivity at high temperature. By exploring the crystal and defect structure of x% Sr/Ca-doped LaPO4 with different nominal Sr/Ca concentrations (x = 0–10) with neutron powder diffraction (NPD) and X-ray powder diffraction (XRD), we confirm that Sr/Ca-doped LaPO4 can exist as self-supported structures at high temperatures during solid oxide fuel cell operation. Thermal stability, surface topography, and size distribution are also studied to better understand the proton conductivity for dry and wet compounds obtained at sintering temperatures ranging from 1200 to 1400 °C using a combination of scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and electrochemical impedance spectroscopy (EIS). The results confirm that Sr-doped samples exhibit the highest proton conductivity of our samples and illustrate the impact of material design and versatile characterization schemes on the development of proton conductors with superior functionality.