Determination of the Nature of the Structural Phase Transitions in 122 Pnictide Systems
Determination of the Nature of the Structural Phase Transitions in 122 Pnictide Systems
复制标题
122 磷元素体系中结构相变性质的测定
DOI：
10.1088/1742-6596/391/1/012134
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Loudon J
中科院分区：
文献类型：
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作者：
Loudon J
用透射电子显微镜研究了新近发现的铁基超导体SrFe2As2和Ba（Fe0.985Co0.015）2As2的四方相到正交相的相变。我们使用的方法，测量的空间分辨序参量，并表明，而在SrFe2As 2的过渡是一个一阶马氏体相变，Ba（Fe0.985Co0.015）2As 2显示连续变化的序参量的相变发生。这通常表明二阶相变，但情况似乎更复杂，因为在过渡期间，样品的不同区域具有不同的序参量值：这应该只发生在一阶变化中。
Transmission electron microscopy was used to investigate the tetragonal-to-orthorhombic phase transitions in SrFe 2 As 2 and Ba (Fe 0.985 Co 0.015) 2 As 2 which are members of the recently discovered iron-based superconductors. We use a method which measures the spatially-resolved order parameter and show that whereas the transition in SrFe 2 As 2 is a first-order martensitic phase change, Ba (Fe 0.985 Co 0.015) 2 As 2 shows a continuous change of the order parameter as the phase transition takes place. This would normally indicate a second order phase transition but the situation seems to be more complicated as, during the transition, different regions of the sample had different values of the order parameter: something which should only happen in a first order change.