Center of Electron Microscopy and State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
Nanoscale. 2017 Jul 20;9(28):9834-9840. doi: 10.1039/c7nr01513e.
The study of first-order structural transformations has attracted extensive attention due to their significant scientific and industrial importance. However, it remains challenging to exactly determine the nucleation sites at the very beginning of the transformation. Here, we report the atomic scale real-time observation of a unique defect-mediated reversible phase transition between the low temperature phase (LTP) and the high temperature phase (HTP) of VO(A). In situ Cs-corrected scanning transmission electron microscopy (STEM) images clearly indicate that both phase transitions (from the HTP to the LTP and from the LTP to the HTP) start at the defect sites in parent phases. Intriguingly, the structure of the defects within the LTP is demonstrated to be the HTP of VO (A), and the defect in the HTP of VO(A) is determined to be the LTP structure of VO(A). These findings are expected to broaden our current understanding of the first-order phase transition and shed light on controlling materials' structure-property phase transition by "engineering" defects in applications.
由于一阶结构相变具有重要的科学和工业意义，因此引起了广泛关注。然而，要准确确定相变开始时的成核位置仍然具有挑战性。在这里，我们报告了在原子尺度上实时观察到的 VO(A)的低温相（LTP）和高温相（HTP）之间独特的缺陷介导的可逆相变。在位 Cs 校正扫描透射电子显微镜（STEM）图像清楚地表明，两个相变（从 HTP 到 LTP 和从 LTP 到 HTP）都从母体相中缺陷的位置开始。有趣的是，LTP 中缺陷的结构被证明是 VO(A)的 HTP，而 VO(A)的 HTP 中的缺陷被确定为 VO(A)的 LTP 结构。这些发现有望拓宽我们对一阶相变的现有认识，并为通过“工程”缺陷来控制材料的结构-性能相变提供启示。
