In situ neutron diffraction study of BaCe0.4Zr0.4Y0.2O3-δ proton conducting perovskite: insight on phase transition and proton transport mechanism.
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
The understanding of protonic defect transport mechanism in Ba(Ce,Zr)O3 perovskites oxides and its proper temperature range of conductivity are fundamentals for materials design and their technological applications as electrolyte for solid oxide fuel and electrolyzer cells, isotopic separation membranes and hydrogen sensors. Structural features of the material, as well as the lattice distortions and proton diffusion, are key factors defining the protonic conduction. The crystal structure of protonated and deuterated BaCe0.4Zr0.4Y0.2O3−δ (BCZY) perovskite and its correlation with protonic transport was studied by in situ Neutron Powder Diffraction (NPD) and complementary Thermogravimetry (TG), Quasi-Elastic Neutron Scattering (QENS) and Isotope Exchange Depth Profiling (IEDP) techniques. A 2nd order phase transition from rhombohedral to cubic symmetry takes place at intermediate temperatures (400 - 600 ºC). Dynamic measurements of NPD allowed the detection of the temperature of the phase transition for BCZY at around 520 ºC. Crystallographic and microstructural parameters, including deuterium occupancy and anisotropic thermal parameters, were determined from high resolution NPD data. The deuterium (and oxygen) occupancy for pre-hydrated BCZY is maximum at low temperature and decreases above 400 ºC, even through the phase transition and beyond 600 ºC. By contrast, proton diffusion increases with temperature above the phase transition. The combination of both effects, deuterium content and diffusion coefficient, explains previous results showing that the proton conductivity dominates the ionic conductivity over the oxygen vacancy mechanism until 600 ºC. The phase transition is mainly related to oxygen sublattice relaxation and does not impact on the protonic transport mechanism.
Date Issued
2022-03-14
Date Acceptance
2022-03-14
Citation
Journal of Materials Chemistry A, 2022, 10 (16), pp.9037-9047
ISSN
2050-7488
Publisher
Royal Society of Chemistry
Start Page
9037
End Page
9047
Journal / Book Title
Journal of Materials Chemistry A
Volume
10
Issue
16
Copyright Statement
© The Royal Society of Chemistry 2022
Identifier
https://pubs.rsc.org/en/content/articlelanding/2022/TA/D1TA10789E
Subjects
Science & Technology
Physical Sciences
Technology
Chemistry, Physical
Energy & Fuels
Materials Science, Multidisciplinary
Chemistry
Materials Science
KINETIC MONTE-CARLO
HIGH-TEMPERATURE
FUEL-CELLS
CHEMICAL-STABILITY
POWDER DIFFRACTION
BARIUM CERATE
DIFFUSION
PERFORMANCE
SCATTERING
CRYSTAL
0303 Macromolecular and Materials Chemistry
0912 Materials Engineering
0915 Interdisciplinary Engineering
Publication Status
Published
Date Publish Online
2022-03-14