Understanding the defect.pdf (692.64 kB)
Understanding the defect chemistry of alkali metal strontium silicate solid solutions: insights from experiment and theory
journal contribution
posted on 2017-01-08, 00:00 authored by R.D. Bayliss, S.N. Cook, D.O. Scanlon, S. Fearn, J. Cabana, C. Greaves, J.A. Kilner, S.J. SkinnerRecent reports of remarkably high oxide ion conduction in a new family of strontium silicates have been
challenged. It has recently been demonstrated that, in the nominally potassium substituted strontium
germanium silicate material, the dominant charge carrier was not the oxygen ion, and furthermore that
the material was not single phase (R. D. Bayliss et. al., Energy Environ. Sci., 2014, DOI: 10.1039/
c4ee00734d). In this work we re-investigate the sodium-doped strontium silicate material that was
reported to exhibit the highest oxide ion conductivity in the solid solution, nominally Sr0.55Na0.45SiO2.775.
The results show lower levels of total conductivity than previously reported and sub-micron elemental
mapping demonstrates, in a similar manner to that reported for the Sr0.8K0.2Si0.5Ge0.5O2.9 composition,
an inhomogeneous chemical distribution correlating with a multiphase material. It is also shown that the
conductivity is not related to protonic mobility. A density functional theory computational approach
provides a theoretical justification for these new results, related to the high energetic costs associated
with oxygen vacancy formation.
Funding
RDB would like to thank the King Abdullah University of Science and Technology for providing resources to complete the work. The UCL/Diamond work presented here made use of the UCL Legion HPC Facility, the IRIDIS cluster provided by the EPSRC funded Centre for Innovation (EP/K000144/1 and EP/ K000136/1), and the ARCHER supercomputer through membership of the UK's HPC Materials Chemistry Consortium, which is funded by EPSRC grant EP/L000202.
History
Publisher Statement
This is a copy of an article published in the Journal of Materials Chemistry A © 2014 Royal Society of Chemistry Publications.Publisher
Royal Society of Chemistryissn
2050-7488Issue date
2014-09-24Usage metrics
Categories
No categories selectedKeywords
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC