Inorganic semiconductors are vital for a number of critical applications but are almost universally brittle. Here, we report the superplastic deformability of indium selenide (InSe). Bulk single-crystalline InSe can be compressed by orders of magnitude and morphed into a Möbius strip or a simple origami at room temperature. The exceptional plasticity of this two-dimensional van der Waals inorganic semiconductor is attributed to the interlayer gliding and cross-layer dislocation slip that are mediated by the long-range In-Se Coulomb interaction across the van der Waals gap and soft intralayer In-Se bonding. We propose a combinatory deformability indicator (Ξ) to prescreen candidate bulk semiconductors for use in next-generation deformable or flexible electronics.

The mechanism responsible for deformation-induced crystalline-to-amorphous transition (CAT) in silicon is still under considerable debate, owing to the absence of direct experimental evidence. Here we have devised a novel core/shell configuration to impose confinement on the sample to circumvent early cracking during uniaxial compression of submicron-sized Si pillars. This has enabled large plastic deformation and in situ monitoring of the CAT process inside a transmission electron microscope. We demonstrate that diamond cubic Si transforms into amorphous silicon through slip-mediated generation and storage of stacking faults (SFs), without involving any intermediate crystalline phases. By employing density functional theory simulations, we find that energetically unfavorable single-layer SFs create very strong antibonding interactions, which trigger the subsequent structural rearrangements. Our findings thus resolve the interrelationship between plastic deformation and amorphization in silicon, and shed light on the mechanism underlying deformation-induced CAT in general.

Chestnut-like SnO 2 and SnO 2 /C nanocomposites with hierarchical structures are synthesized by hydrothermally oxidizing Sn nanoparticles in glucose solution. Structural characterizations using SEM and TEM reveal that the SnO 2 nanoparticles are composed of numerous, randomly arranged SnO 2 nanosheets with hollow cores. Owing to the short electron and ion diffusion distances and transformation strain accommodation mechanism of this structure, the new SnO 2 /C nanocomposites exhibit enhanced lithium ion storage properties with a capacity of ~ 930 mA h g-1 and capacity retention of about 96% after 100 cycles at 0.1 C. An in situ TEM study of the electrochemically driven lithiation/delithiation of SnO 2 /C nanocomposites reveals that their enhanced cycling stability is mainly facilitated by the limited volume expansion and excellent mechanical robustness of the hollow chestnuts.

Inorganic semiconductors exhibit multifarious physical properties, but they are prevailingly brittle, impeding their application in flexible and hetero-shaped electronics. The exceptional plasticity discovered in InSe crystal indicates the existence of abundant plastically deformable two-dimensional van der Waals (2D vdW) materials, but the conventional trial-and-error method is too time-consuming and costly. Here we report on the discovery of tens of potential 2D chalcogenide crystals with plastic deformability using a nearly automated and efficient high-throughput screening methodology. Seven candidates e.g., famous MoS2, GaSe, and SnSe2 2D materials are carefully verified to show largely anisotropic plastic deformations, which are contributed by both interlayer and cross-layer slips involving continuous breaking and reconstruction of chemical interactions. The plasticity becomes a new facet of 2D materials for deformable or flexible electronics.

Despite their energy-efficient merits as promising light-weight structural materials, magnesium (Mg) based alloys suffer from inadequate corrosion resistance. One primary reason is that the native surface film on Mg formed in air mainly consists of Mg(OH)2 and MgO, which is porous and unprotective, especially in humid environments. Here, we demonstrate an environmentally benign method to grow a protective film on the surface of Mg/Mg alloy samples at room temperature, via a direct reaction of already-existing surface film with excited CO2. Moreover, for samples that have been corroded obviously on surface, the corrosion products can be converted directly to create a new protective surface. Mechanical tests show that compared with untreated samples, the protective layer can elevate the yield stress, suppress plastic instability and prolong compressive strains without peeling off from the metal surface. This environmentally friendly surface treatment method is promising to protect Mg alloys, including those already-corroded on the surface.

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Si pillars fabricated by focused ion beam (FIB) had been reported to have a critical size of 310–400 nm, below which their deformation behavior would experience a brittle-to-ductile transition at room temperature. Here, we demonstrated that the size-dependent transition was actually stemmed from the amorphous Si (a-Si) shell introduced during the FIB fabrication process. Once the a-Si shell was crystallized, Si pillars would behave brittle again with their modulus comparable to their bulk counterpart. The analytical model we developed has been proved to be valid in deriving the moduli of crystalline Si core and a-Si shell.

Ceramics possess high temperature resistance, extreme hardness, high chemical inertness and a lower density compared to metals, but there is currently no technology that can produce satisfactory joints in ceramic parts and preserve the excellent properties of the material. The lack of suitable joining techniques for ceramics is thus a major road block for their wider applications. Herein we report a technology to weld ceramic nanowires, with the mechanical strength of the weld stronger than that of the pristine nanowires. Using an advanced aberration-corrected environmental transmission electron microscope (ETEM) under a CO2 environment, we achieved ceramic nanowelding through the chemical reaction MgO + CO2 → MgCO3 by using porous MgO as the solder. We conducted not only nanowelding on MgO, CuO, and V2O5 nanowires and successfully tested them in tension, but also macroscopic welding on a ceramic material such as SiO2, indicating the application potential of this technology in bottom-up ceramic tools and devices.