Structural origin of the enhanced ionic conductivity upon Nb doping in Sr11Mo4O23 defective double perovskite. Issue 12 (7th March 2017)

• Record Type: Journal Article
• Authors: Miranda, C. D.; López, C. A.; Pedregosa, J. C.; Alonso, J. A.
• Is Part Of: Dalton transactions. Volume 46:Issue 12(2017)
• Page Start: 3934
• Page End: 3942
• Publication Date: 2017-03-07
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c7dt00340d
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : We report a substantial enhancement of the oxide-ion conductivity in Sr11 Mo4 O23 achieved by Nb doping the Mo sites. Abstract : We report a substantial enhancement of the oxide-ion conductivity in Sr11 Mo4 O23 achieved by Nb doping the Mo sites. This series responds to the formula: Sr11 Mo4− x Nb x O23− 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 Sr11 Mo4 O23 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.