铁电性
材料科学
八面体
格子(音乐)
空位缺陷
结晶学
凝聚态物理
扫描透射电子显微镜
亚稳态
电子
离子
透射电子显微镜
晶体结构
物理
纳米技术
化学
电介质
光电子学
量子力学
声学
作者
Changjin Guo,Jiajun Zhu,Xia-Li Liang,Caifu Wen,Jiyang Xie,Chengding Gu,Wanbiao Hu
标识
DOI:10.1038/s41467-024-54229-7
摘要
CuInP2S6 (CIPS) is an emerging 2D ferroelectric material known for disrupting spatial inversion symmetry due to Cu(I) position switching. Its ferroelectricity strongly relies on the Cu(I) atom/ion occupation ordering and dynamics. Nevertheless, the accurate Cu(I) occupations and correlated migration dynamics under the externally applied energy, which are key to unlocking ferroelectric properties, remain controversial and unresolved. Herein, an atomic-level direct imaging through aberration-corrected scanning transmission electron microscopy is performed to precisely trace the Cu(I) dynamic behaviours under electron-beam irradiation along (100)-CIPS. It clearly demonstrates that Cu(I) possesses multiple occupations, and Cu(I) could migrate to the lattice, vacancy, interstitial and interlayer sites between the InS6 octahedral skeletons of CIPS to form local CuxInP2S6 (x = 2-4) structure. Cu(I) multi-occupations induced lattice stress results in a layer sliding along the b-axis direction generating a sliding size of 1/6 b lattice constant. The CuxInP2S6 (x = 2-4) exists in a type of dynamic structure, only metastable with electron dose over 50 e− Å−2, thus generating a dynamic process of $${\mbox{C}}{{\mbox{u}}}_{x}{\mbox{In}}{{\mbox{P}}}_{2}{{\mbox{S}}}_{6}(x=2-4)\rightleftharpoons {\mbox{CuIn}}{{\mbox{P}}}_{2}{{\mbox{S}}}_{6}$$ , a completely unreported phenomenon. These findings shed light on the unveiled mechanism underlying Cu(I) migration in CIPS, providing crucial insights into the fundamental processes that govern its ferroelectric properties. The authors demonstrate that Cu(I) possesses multiple occupations, and Cu(I) migrate to the lattice, vacancy, interstitial and interlayer sites between the InS6 octahedral skeletons of CuInP2S6 to form local CuxInP2S6 (x = 2-4) structure.
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