Lookup NU author(s): Dr Stevin Pramana
This is the authors' accepted manuscript of an article that has been published in its final definitive form by Royal Society of Chemistry, 2019.
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The crystal structure of a (3 + 2)D incommensurate modulated LaNb0.88W0.12O4.06 phase, a novel oxygen ionic conductor, is refined using a combination of synchrotron X-ray diffraction and electron diffraction data. The superspace group I2/c(α10γ1)00(α20γ2)00 (a = 5.4131(1) Å, b = 11.6432(2) Å, c = 5.2963(1) Å, β = 91.540(1)°, q1 = 0.2847(5)a* + 0.1098(9)c* and q2 = −0.1266(9)a* + 0.2953(1)c*) was chosen for the refinement. Similar to other scheelite type modulated structures, the modulation of LaNb0.88W0.12O4.06 stems from the cation occupancy ordering in the xz plane. To facilitate the modulated cation sub-lattice, and to compensate for the difference in their size and charge, the B site polyhedra are distorted by stretching the B-O bond lengths. Consequently, an extension in the B site coordination number from 6 to 8 is observed in the modulated phase. An interconnected 3D network of BOx polyhedra, similar to that of modulated CeNbO4.25, is obtained as a result of the structure modulation, which is not present in the unmodulated parent structure. Oxygen tracer diffusivity measurements indicate that the composition is an oxygen ion conductor, which relies on an interstitialcy conduction mechanism with a diffusion coefficient of 2.46 × 10-9 cm2 s-1, at 750 °C reported.
Author(s): Cheng L, Pramana SS, Skinner SJ
Publication type: Article
Publication status: Published
Journal: Dalton Transactions
Print publication date: 07/02/2019
Online publication date: 03/12/2018
Acceptance date: 02/12/2018
Date deposited: 07/12/2018
ISSN (print): 1477-9226
ISSN (electronic): 1477-9234
Publisher: Royal Society of Chemistry
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