High-mobility layered semiconductors have the potential to enable the next-generation electronics and computing. This paper demonstrates that the ultrahigh electron mobility observed in the layered semiconductor Bi2O2Se originates from an incipient ferroelectric transition that endows the material with a robust protection against mobility degradation by Coulomb scattering. Based on first-principles calculations of electron–phonon interaction and ionized impurity scattering, it is shown that the electron mobility of Bi2O2Se can reach 104 to 106 cm2 V–1 s–1 over a wide range of realistic doping concentrations. Furthermore, a small elastic strain of 1.7% can drive the material toward a unique interlayer ferroelectric transition, resulting in a large increase in the dielectric permittivity and a giant enhancement of the low-temperature electron mobility by more than an order of magnitude. These results establish a new route to realize high-mobility layered semiconductors via phase and dielectric engineering.

On account of the high theoretical capacity and preferable electrochemical reversibility, tin selenides have emerged as potential anode materials in the field of sodium ion batteries (SIBs). Unfortunately, the large volume changes, low electrical conductivity, and shuttling effect of polyselenides have impeded their real application. In this work, we present a spatially confined reaction approach for controllable fabrication of SnSe spheres, which are embedded in polydopamine (PDA)-derived N, Se dual-doped carbon networks (SnSe@NSC) through a one-step carbonization and selenization method. The NSC shell can not only buffer the volume changes during the cycling but also ensure strong coupling interaction between the SnSe core and carbon shell through Sn–C bonds, leading to excellent conductivity and structural integrity of the composite. Meanwhile, DFT theory calculations confirm that N, Se codoping in the carbon shell can endow the composite with enhanced adsorption energy and accelerated transfer ability of Na+. Consequently, the SnSe@NSC anode exhibits a high discharge capacity of 302.6 mA h g–1 over 500 cycles at 1 A g–1 and a competitive rate capability of 285.3 mA h g–1 at 10 A g–1. Additionally, a sodium ion full battery is assembled by coupling the SnSe@NSC anode with the cathode of Na3V2(PO4)3 and verified with good cycling durability (190 mA h g–1 at 1 A g–1 over 500 cycles) and high energy density (204.3 W h kg–1). Our scalable and facile design of heterostructured SnSe@NSC provides a new avenue to develop novel advanced anode materials for SIBs.

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Phase engineering by strain in 2D semiconductors is of great importance for a variety of applications. Here, a study of the strain-induced ferroelectric (FE) transition in bismuth oxyselenide (Bi 2 O 2 Se) films, a high-performance (HP) semiconductor for next-generation electronics, is presented. Bi 2 O 2 Se is not FE at ambient pressure. At a loading force of ≳400 nN, the piezoelectric force responses exhibit butterfly loops in magnitude and 180°phase switching. By carefully ruling out extrinsic factors, these features are attributed to a transition to the FE phase. The transition is further supported by the appearance of a sharp peak in optical second-harmonic generation under uniaxial strain. In general, solids with paraelectrics at ambient pressure and FE under strain are rare. The FE transition is discussed using first-principles calculations and theoretical simulations. The switching of FE polarization acts as a knob for Schottky barrier engineering at contacts and serves as the basis for a memristor with a huge on/off current ratio of 10 6 . This work adds a new degree of freedom to HP electronic/optoelectronic semiconductors, and the integration of FE and HP semiconductivity paves the way for many exciting functionalities, including HP neuromorphic computing and bulk piezophotovoltaics.

We propose a van der Waals heterostructure CuInP2S6/germanene by combining two dimensional ferroelectric semiconductor CuInP2S6 with germanene. By density functional theory calculations, we find that the metal-semiconductor transition can be realized in the CuInP2S6/germanene heterostructure by controlling the ferroelectric polarization direction. CuInP2S6 induces the sublattice imbalance of germanene by interface interaction and thus makes it become a normal semiconductor. Then, two opposite ferroelectric polarization states in CuInP2S6/germanene lead to a different band alignment and finally determine its metallic or semiconductor properties. Large transition barriers from ferroelectric to antiferroelectric phases ensure its stability at room temperature. This is a pure electric field controlled metal-semiconductor transition, which has great application potential for exploring nonvolatile ferroelectric switches and memory devices.

The front of the Zoulang Nanshan Caledonian volcanic island arc zone in the northern Qilian Mountains is a forearc accretionary terrane, composed of multiple accretionary volcanic island arcs, flysch accretionary wedges, high ‐ pressure metamorphosed detachment zones and remnants of ophiolites. It resulted from the northeastward subduction of the Early Palaeozoic Qilan oceanic crust beneath the Alxa block. High ‐ pressure metamorphism, which occurred during the subduction, progressed through three stages: the initial stage of medium T ‐ high P, the main stage of temperature decrease and pressure increase, and the lag stage of pressure decrease and temperature increase. Finally the paper presents a retrotrench subduction dynamic model indicative of northward subduction of the central Qilian block and southward accretion of the Alxa block during the period of 450‐500 M a.

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