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Issue 12, 2017
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Structural origin of the enhanced ionic conductivity upon Nb doping in Sr11Mo4O23 defective double perovskite

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Abstract

We report a substantial enhancement of the oxide-ion conductivity in Sr11Mo4O23 achieved by Nb doping the Mo sites. This series responds to the formula: Sr11Mo4−xNbxO23−δ (with x = 0.0, 0.5 and 1.0). The original structure can be related to the conventional double perovskite; however, it presents a broken corner sharing connectivity of the octahedral framework, hence leading to a complex and highly defective network. The samples were prepared via citrate precursor method, followed by thermal treatments at 1300 °C for 12 hours in air. The crystal structures were refined from X-ray and neutron powder diffraction (NPD) data. A phase transition from tetragonal to cubic symmetry is identified in a temperature-dependent NPD study, driven by an oxygen delocalization effect. The ionic conductivity measured by impedance spectroscopy is enhanced upon Nb-doping; the x = 1 doped phase exhibits a threefold increase compared to the pristine Sr11Mo4O23 oxide, with conductivity values of 7.6 × 10−3 and 2.7 × 10−2 S·cm−1 at 650 and 800 °C, which are even greater than for YSZ in the 650–800 °C temperature range, and close to those reported for other state-of-the art solid-oxide electrolytes.

Graphical abstract: Structural origin of the enhanced ionic conductivity upon Nb doping in Sr11Mo4O23 defective double perovskite

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Publication details

The article was received on 28 Jan 2017, accepted on 28 Feb 2017, published on 28 Feb 2017 and first published online on 28 Feb 2017


Article type: Paper
DOI: 10.1039/C7DT00340D
Citation: Dalton Trans., 2017,46, 3934-3942
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    Structural origin of the enhanced ionic conductivity upon Nb doping in Sr11Mo4O23 defective double perovskite

    C. D. Miranda, C. A. López, J. C. Pedregosa and J. A. Alonso, Dalton Trans., 2017, 46, 3934
    DOI: 10.1039/C7DT00340D

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