SrFe_(1.5-x)Co_xO_(3.25+δ)体系结构、相组成和电导研究

Structure, Phase Composition and Conductivity Study of Mixed Conductor SrFe_(1. 5 -x)Co_xO_(3. 25 +δ)

利用碘量法测定了ＳｒＦｅ_（１．５－ｘ）ＣＯ_ｘＯ_（３．２５＋δ）系列样品在不同温度下的金属平均价态，结合ＸＲＤ谱图研究了温度、钴含量对其结构、相组成的变化的影响规律。研究发现：随钻含量增加，体系由层状相过渡到钙钛矿相，并伴随有尖晶石相的出现。此外，由交流四端子法测量了ＳｒＦｅ_（１．５－ｘ）Ｃｏ_ｘＯ_（３．２５＋δ）系列样品的总电导率随钴含量的变化关系，总电导率随钻含量和温度的升高而增大，但对于钻含量较多的样品，电导率在～９００℃附近的较窄的温度范围内，出现一最大值。本文探讨了出现这一现象的可能原因。

The average valence of Fe/Co in SrFe_(1.5 -x)Co_xO_(3.25+δ) systems was determined by iodometric titration. The structure of SrFe_(1.5 -x)Co_xO_(3.25+δ) was determined by X-ray powder diffraction. When the Co ions content increase, Sr_4Fe_(6-x)Co_xO_z layered-phase transforms to perovskite phase, with the appearance of the spinel phase. The electrical conductivities of the samples increase with temperature and the cobalt content, while for the samples with higher cobalt content, a maximum appears around 900℃, which can be attributed to the changes of phase composition.