Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
Department of Geological Sciences, Stanford University, Stanford, California 94305, United States.
J Am Chem Soc. 2022 Dec 28;144(51):23595-23602. doi: 10.1021/jacs.2c10884. Epub 2022 Dec 19.
Low-dimensional metal halides exhibit strong structural and electronic anisotropies, making them candidates for accessing unusual electronic properties. Here, we demonstrate pressure-induced quasi-one-dimensional (quasi-1D) metallicity in δ-CsSnI. With the application of pressure up to 40 GPa, the initially insulating δ-CsSnI transforms to a metallic state. Synchrotron X-ray diffraction and Raman spectroscopy indicate that the starting 1D chain structure of edge-sharing Sn-I octahedra in δ-CsSnI is maintained in the high-pressure metallic phase while the SnI octahedral chains are distorted. Our experiments combined with first-principles density functional theory calculations reveal that pressure induces Sn-Sn hybridization and enhances Sn-I coupling within the chain, leading to band gap closure and formation of conductive SnI distorted octahedral chains. In contrast, the interchain I...I interactions remain minimal, resulting in a highly anisotropic electronic structure and quasi-1D metallicity. Our study offers a high-pressure approach for achieving diverse electronic platforms in the broad family of low-dimensional metal halides.
低维金属卤化物表现出强烈的结构和电子各向异性，使它们成为获得异常电子性质的候选材料。在这里，我们证明了 δ-CsSnI 中存在压力诱导的准一维（准 1D）金属性。通过施加高达 40 GPa 的压力，最初绝缘的 δ-CsSnI 转变为金属态。同步加速器 X 射线衍射和拉曼光谱表明，在高压金属相中，边缘共享 Sn-I 八面体的 δ-CsSnI 的起始 1D 链结构得以保持，而 SnI 八面体链发生了扭曲。我们的实验结合第一性原理密度泛函理论计算表明，压力诱导了 Sn-Sn 杂化，并增强了链内的 Sn-I 耦合，导致带隙闭合和形成导电 SnI 扭曲八面体链。相比之下，链间的 I...I 相互作用仍然很小，导致具有高度各向异性的电子结构和准 1D 金属性。我们的研究为在广泛的低维金属卤化物家族中实现多样化的电子平台提供了一种高压方法。
