3D anisotropic functional properties (such as magnetic, electrical, thermal, and optical properties, etc.) in a single material are not only beneficial to the multipurpose of a material, but also helpful to enrich the regulatory dimensionality of functional materials. Herein, a colossal 3D electrical anisotropy of layered MAB-phase MoAlB single crystal is introduced and dissected. Using high-temperature metal-solution method, high-quality MoAlB single crystals are obtained and a surprisingly strong out-of-plane ( σ a / σ b = 1.43 × 10 5 , at 2 K) and in-plane ( σ a / σ c = 12.12, at 2 K) electrical anisotropies are first observed. After a series of experimental and theoretical investigations, it is demonstrated that the 3D anisotropic crystal structure and chemical bond of MoAlB result in its 3D anisotropic phonon vibration and electronic structure, influence the corresponding electron-electron as well as electron-phonon interactions, and finally give rise to its colossal 3D anisotropy of electrical conductivity. This work experimentally and theoretically proves MoAlB single crystal possessing the 3D anisotropies of crystal structure, chemical bond, phonon vibration, electronic structure, and electrical transport, but also provides a promising platform for the future design of functionalized electronic devices as well as synthesis of new and large-sized in-plane anisotropic 2D material (MoBene).
Di Wu,Jiao Shi,Xiaoming Zheng,Jinxin Liu,Weidong Dou,Yongli Gao,Xiaoming Yuan,Fangping Ouyang,Han Huang
One-dimensional (1D) atomically thin crystals have attracted considerable interest due to their unique properties and potential applications. Herein, the chemical vapor deposition (CVD) growth of molybdenum disulfide (MoS 2 ) nanoribbons on sapphire(0001) supported monolayer MoS 2 flakes without catalysts as well as the characterizations by means of Raman and photoluminescence (PL) spectroscopy, optical microscopy (OM), atomic force microscopy (AFM), and scanning transmission electron microscopy (STEM). The Raman and PL results is reported, as well as OM images reveal that such MoS 2 nanoribbons grow on monolayer MoS 2 flakes. STEM and selected area electron diffraction (SAED) results reveal that they are grown along the 〈 10 1 ¯ 0 〉 direction with atomically sharp edges. Controlled experiments show that the deficiency of sulfur vapor at the beginning of growth induced 1D MoO x S 2− x crystals as precursors. The subsequent sulfurization changes them into MoS 2 nanoribbons. These findings provide a facile approach to MoS 2 nanoribbons and enrich the horizon of the preparation of nanostructured transition metal dichalcogenides.
The materials with quasi-one-dimensional crystal structure have gained intense interest because of their novel structure and related properties such as electron correlations , charge-density wave and potential superconductivity . Here we report two new Ni-based quasi-one-dimensional selenides : Rb 0.9 Ni 3.1 Se 3 and K 0.7 Ni 3.1 Se 3 . These two compounds are nonstoichiometric and composed of one-dimensional (Ni 3 Se 3 ) ∞ infinite chains with face-sharing Ni 6 octahedra along the c direction. It is found that the interchain distance in these compounds is strongly influenced by the radius of intercalated alkali-metal cations, while the configuration of (Ni 3 Se 3 ) ∞ chains is basically unaffected. The conductivity measurement indicates the metallic behavior of Rb 0.9 Ni 3.1 Se 3 and K 0.7 Ni 3.1 Se 3 . Meanwhile, the magnetic susceptibility reveals the spin-glass state below 10 K. It is indicated that the magnetic moments in these compounds are related to the Ni Ni bonding distance. First-principles calculation reproduces the metallic state of this 133 phase, and also suggests that the magnetic interaction is attributed to the extra Ni in structure. These compounds form a Ni-based quasi-one-dimensional material family, which provides new platform to understand the structure-property relationship of quasi-one-dimensional materials, and also offer a series of potential precursors to synthesis the novel (Ni 3 Se 3 ) ∞ molecular wires .
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