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1:1:1 triple-cation B-Site-ordered and oxygen-deficient perovskite Ca4GaNbO8: a member of a family of anion-vacancy-based cation-ordered complex perovskites

DOI: 10.1021/ic302414u DOI Help

Authors: Tao Yang (University of Liverpool) , John B. Claridge (University of Liverpool) , Matthew J. Rosseinsky (University of Liverpool)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Inorganic Chemistry , VOL 52 (7) , PAGES 3795 - 3802

State: Published (Approved)
Published: April 2013

Abstract: Exploration of the Ca–Ga–Nb–O phase diagram by solid-state reaction in air led to isolation of Ca4GaNbO8. The crystal structure was determined ab initio by synchrotron X-ray and high-resolution neutron powder diffraction. Ca4GaNbO8 adopts a heavily distorted oxygen-deficient perovskite structure with the rare feature of complete ordering of the three B-site cations, driven by their distinct chemistries. One of the calcium cations occupies a distorted octahedral cavity and together with tetrahedrally coordinated Ga and octahedrally coordinated Nb is considered as a B-site cation in the ABO3–x perovskite. This interpretation of the structure reveals Ca4GaNbO8 is part of a family of B-site and vacancy-ordered perovskites related to mineral structures. The anion-vacancy ordering pattern in Ca4GaNbO8 is driven by the coordination preferences of the three structurally distinct cations and correlated with the ordering of each cation on a distinct site. Alternating current impedance spectra show Ca4GaNbO8 is insulating (bulk conductivity 10–5–10–7 S·cm–1) over the measured temperature range 550–950 °C with an activation energy of 1.10(3) eV.

Subject Areas: Chemistry, Materials

Instruments: I11-High Resolution Powder Diffraction

Added On: 05/04/2013 13:15

Discipline Tags:

Physical Chemistry Chemistry Materials Science Inorganic Chemistry Perovskites Metallurgy

Technical Tags:

Diffraction X-ray Powder Diffraction