Synthesis and characterisation of new Bi(iii)-containing apatite-type oxide ion conductors: the influence of lone pairs. Issue 37 (12th September 2017)

• Record Type: Journal Article
• Authors: Tate, M. L.; Fuller, C. A.; Avdeev, M.; Brand, H. E. A.; McIntyre, G. J.; Radosavljevic Evans, I.
• Is Part Of: Dalton transactions. Volume 46:Issue 37(2017)
• Page Start: 12494
• Page End: 12499
• Publication Date: 2017-09-12
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c7dt02871g
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : New Bi-containing apatite-type germanates, characterised by X-ray and neutron diffraction, impedance spectroscopy and bond valence analysis, display high oxide ion conductivity. Abstract : Lone-pair cations are known to enhance oxide ion conductivity in fluorite- and Aurivillius-type materials. Among the apatite-type phases, the opposite trend is found for the more widely studied silicate oxide ion conductors, which exhibit a dramatic decrease in conductivity on Bi(iii ) incorporation. In this work, the influence of lone-pair cations on the properties of apatite-type germanate oxide ion conductors has been investigated by preparing and characterising seven related compositions with varying Bi(iii ) content, by X-ray and neutron powder diffraction and impedance spectroscopy. All materials are very good oxide ion conductors (with conductivities of up to 1.29 × 10 −2 S cm −1 at 775 °C). Increasing Bi(iii ) content leads to increases in conductivity by up to an order of magnitude, suggesting significant differences in the oxide-ion conduction mechanisms between lone-pair-containing apatite-type germanate and silicate solid electrolytes.