Structure and properties of a quasi-one-dimensional compound BaTiS3 under pressure

We report the studies of structure and properties of a quasi-one-dimensional (quasi-1D) compound BaTiS3 under pressure. The poly-crystalline samples are synthesized by solid-state reaction method and single-crystalline samples are produced by chemical vapor transport method. The XRD measurement under ambient pressure confirms the hexagonal structure, which consists of face-sharing octahedral TiS6 chains along c-axis and displays a quasi-1D feature. When applying pressure, the synchrotron X-ray diffraction experiments show that the sample undergoes a phase transition from hexagonal phase to orthorhombic phase at around 10 GPa due to the zig–zag deformation of TiS6 chains, while the quasi-1D structure is reserved. At ambient pressure, BaTiS3 exhibits an insulating behavior with a band gap about 0.273 eV. When applying pressure, the sample undergoes a crossover from insulator to metal due to the enhancement of inter-chain electron hopping.我们报道了压力条件下准一维（quasi-1D）化合物BaTiS3的结构与物性研究。本研究采用固相反应法合成多晶样品，并通过化学气相传输法制备单晶样品。常压下的X射线衍射（X-ray Diffraction，XRD）测试证实，该样品具有六方晶体结构：其沿c轴方向存在由共面八面体TiS6构成的链状结构，呈现准一维特性。施加压力时，同步辐射X射线衍射（synchrotron X-ray diffraction）实验表明，由于TiS6链发生锯齿形形变，该样品在约10吉帕斯卡（GPa）处经历了从六方相向正交相的相变，但其准一维结构得以保留。常压下，BaTiS3表现出绝缘行为，带隙约为0.273电子伏特（eV）。施加压力时，随着链间电子跃迁作用增强，该样品发生从绝缘体到金属态的转变。