School of Chemistry, University of Birmingham, Birmingham, B15 2TT, UK.
Dalton Trans. 2011 May 28;40(20):5599-603. doi: 10.1039/c1dt10253b. Epub 2011 Apr 14.
In this paper we report the successful incorporation of silicon into SrMO(3) (M = Co, Mn) leading to a structural change from a hexagonal to a cubic perovskite. For M = Co, the cubic phase was observed for low doping levels (3%), and these doped phases showed very high conductivities (up to ≈350 Scm(-1) at room temperature). However, annealing studies at intermediate temperatures (700-800 °C), indicated that the cubic phase was metastable with a gradual transformation to a hexagonal cell on annealing. Further work showed that co-doping with Fe resulted in improved stability of the cubic phase; a composition SrCo(0.85)Fe(0.1)Si(0.05)O(3-y) displayed good stability at intermediate temperatures and a high conductivity (≈150 Scm(-1) at room temperature). For M = Mn, the work showed that higher substitution levels were required to form the cubic perovskite (≈15% Si doping), although in these cases the phases were shown to be stable to annealing at intermediate temperatures. Conductivity measurements again showed an enhancement in the conductivity on Si doping, although the conductivities were lower (≈0.3-14 Scm(-1) in the range 20-800 °C) than the cobalt containing systems. The conductivities of both systems suggest potential for use as cathode materials in solid oxide fuel cells.
在本文中，我们成功地将硅掺入 SrMO(3)（M = Co、Mn）中，导致其结构从六方钙钛矿转变为立方钙钛矿。对于 M = Co，在低掺杂水平（3%）下观察到立方相，这些掺杂相表现出非常高的电导率（在室温下高达 ≈350 S cm(-1)）。然而，在中间温度（700-800°C）下的退火研究表明，立方相是亚稳的，在退火过程中逐渐转变为六方晶胞。进一步的工作表明，与 Fe 共掺杂导致立方相的稳定性提高；SrCo(0.85)Fe(0.1)Si(0.05)O(3-y) 组成在中间温度下表现出良好的稳定性和高电导率（在室温下约为 150 S cm(-1)）。对于 M = Mn，研究表明需要更高的取代水平才能形成立方钙钛矿（约 15%的 Si 掺杂），尽管在这些情况下，这些相在中间温度退火时被证明是稳定的。电导率测量再次表明，Si 掺杂会提高电导率，尽管电导率较低（在 20-800°C 范围内约为 0.3-14 S cm(-1)），低于钴基系统。这两个系统的电导率都表明它们有可能用作固体氧化物燃料电池的阴极材料。
