Tate M L, Fuller C A, Avdeev M, Brand H E A, McIntyre G J, Radosavljevic Evans I
Durham University, Department of Chemistry, Science Site, South Road, Durham, DH1 3LE, UK.
Dalton Trans. 2017 Sep 26;46(37):12494-12499. doi: 10.1039/c7dt02871g.
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 S cm 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.
已知孤对阳离子可提高萤石型和奥里维利乌斯型材料中的氧离子传导率。在磷灰石型相中，对于研究更为广泛的硅酸盐氧离子导体，发现了相反的趋势，即在掺入Bi(III)后，其传导率会急剧下降。在这项工作中，通过制备和表征七种Bi(III)含量不同的相关组合物，利用X射线和中子粉末衍射以及阻抗谱，研究了孤对阳离子对磷灰石型锗酸盐氧离子导体性能的影响。所有材料都是非常好的氧离子导体（在775°C时传导率高达1.29×10 S cm）。Bi(III)含量的增加导致传导率提高了一个数量级，这表明含孤对的磷灰石型锗酸盐和硅酸盐固体电解质之间的氧离子传导机制存在显著差异。
