Complex octahedral tilt phases in the ferroelectric perovskite system LixNa1–xNbO3
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High-temperature phase behavior in the system LixNa1−xNbO3 has been studied by using high-resolution neutron powder diffraction. Each of the three compositions studied in the Na-rich part of the phase diagram (viz., x=0.03,0.08, and 0.12) shows evidence for distinct and complex structural modulations based on different tilting schemes of NbO6 octahedral units. Whilst octahedral tilting is prevalent in the structural chemistry of perovskites the details of the long-range tilt phases are distinct from those previously observed in NaNbO3 itself. A phase with a well-defined fourfold superlattice is observed for the composition Li0.12Na0.88NbO3, and yet more complex phases with modulations based on 20-fold and 30-fold repeats are observed for Li0.03Na0.97NbO3 and Li0.08Na0.92NbO3, respectively. This peculiar structural frustration makes the system LixNa1−xNbO3 a most structurally complex “simple” perovskite.
Dixon , C A L & Lightfoot , P 2018 , ' Complex octahedral tilt phases in the ferroelectric perovskite system Li x Na 1–x NbO 3 ' , Physical Review. B, Condensed matter and materials physics , vol. 97 , no. 22 . https://doi.org/10.1103/PhysRevB.97.224105
Physical Review. B, Condensed matter and materials physics
© 2018 American Physical Society. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1103/PhysRevB.97.224105
DescriptionWe thank STFC for provision of neutron diffraction facilities at ISIS and Dr Aziz Daoud-Aladine for experimental assistance. CALD was supported by an EPSRC DTA studentship (EP/L50579/1).
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