Xing Li

Diamond has been recognized as the ultimate semiconductor due to its ultra‐wide bandgap, exceptional carrier mobility, high breakdown voltage, and superior thermal conductivity. However, its application in memristors is significantly limited by challenges in modulating its electrical conductivity and its chemical stability. Here, by leveraging the rapid metal‐diamond reactions at diamond grain boundaries (GBs), we constructed vertical ion migration channels along the GBs and realized the nonvolatile resistive switching behavior in polycrystalline diamond (Poly‐D). The diamond memristor presents a high switching ratio (∼10 ⁴ ) along with reliable cycling and retention performance over a wide temperature range from ‐150°C to 600°C. In‐situ biasing transmission electron microscopy observations confirm the reproducible formation and rupture of Ag conductive filaments (Ag CFs) along the constructed channels at the GBs. The diamond memristor demonstrates its capabilities as an artificial synapse and in biological nociception. Our work demonstrates the application of diamond in memristors and highlights its potential for neuromorphic computing, particularly under extreme conditions.

β-Ga2O3 exhibits great potential for next-generation power electronics, while its low thermal conductivity poses a challenge to efficient heat dissipation. We address this challenge by developing a gallium-assisted epitaxial strategy to synthesize highly oriented β-Ga2O3 film on diamond. The β-Ga2O3 presents a high thermal conductivity of 9.0 W m−1 K−1 and low thermal boundary resistance of 6.05 m2 K GW−1. In-situ experiments reveal a high interfacial bonding strength (>2.09 GPa), resulting from the atomically sharp and covalently bonded interface. The identified new interfacial phonon mode at ∼60 meV through the vibrational electron energy-loss spectroscopy can significantly enhance the phonon transport between diamond and β-Ga2O3. The developed gallium-assisted strategy may mitigate the thermal constraints of β-Ga2O3, offering a promising route for the heterointegration of β-Ga2O3-based power devices with diamond.

Diamond, an archetype of hardness and brittleness, can nonetheless display striking elastic compliance at the nanoscale, in sharp contrast to its ultrastiff, fracture prone bulk behavior. Despite recent experimental progress, the atomic scale origin of this anomalous elasticity remains unresolved. Here, we uncover a pronounced size- dependent softening in nanodiamond, with the effective axial Young’s modulus decreasing from about 1000 to about 700 GPa as the particle diameter shrinks from 13 to 4 nm. By integrating transmission electron microscopy nanomechanical testing with first principles calculations and molecular dynamics simulations, we show that this stiffness reduction does not arise from the surface atomic layers, which remain comparatively stiff, but instead from weakened bonding in a distinct interfacial region between the surface and the crystalline core. These under-coordinated regions localize strain and accommodate large elastic deformation. The results uncover a previously overlooked interfacial mechanism that governs elasticity in brittle nanomaterials and offer design principles for nanomechanical resonators, quantum devices, and thermal transport applications with tunable stiffness.

Diamond, composed of sp³ covalent carbon bonds, is renowned for its exceptional hardness, thermal conductivity, and wide bandgap, yet its intrinsic brittleness severely limits deformation and processing. Here, we report an amorphization-mediated ultralarge plasticity in nanodiamonds using a custom-designed in-situ transmission electron microscopy mechanical holder. Unlike conventional mechanisms such as dislocation motion or crystalline phase transformation, the deformation is governed by the formation of an interconnected amorphous carbon network that accommodates stress and enables cooperative grain rotation and sliding. This amorphization-mediated plasticity allows nanodiamonds to sustain compressive strains exceeding 90% without fracture. A distinct size-dependent transition is identified: ultralarge plasticity occurs only below ~13 nm, while larger diamonds deform in a brittle manner. This work provides critical insights into nanoscale mechanics and offering exciting opportunities for diamond-based nano-manufacturing, strain engineering, and advanced quantum or electronic device applications.

β-Ga2O3/diamond heterojunctions demonstrate considerable potential for applications in electronics and optoelectronics. However, theoretical investigations into their electrical properties remain largely unexplored. In this study, we provide a detailed examination of the electrical properties in β-Ga2O3/diamond heterojunctions with various experimentally reported surface combinations. All heterojunctions exhibit type-II band alignment, with valence band offsets (VBOs) ranging from 1.84 to 2.78 eV owing to material anisotropy and mismatch-induced strains. Furthermore, the influence of H-termination on the β-Ga2O3/diamond heterojunction was systematically investigated. Results indicate that H-termination significantly increases the VBOs by 1.11–1.88 eV while introducing a van der Waals barrier that impedes carrier transport. At covalent-bonded interfaces, band bending reduces the interface barrier, thereby facilitating carrier transport. Finally, the application prospects of these heterojunctions were comprehensively explored. This work offers theoretical insights for the co-design of β-Ga2O3/diamond heterojunctions.

The β-Ga₂O₃/SiC heterojunction exhibits significant application potential across multiple fields. This work systematically investigates the influence of β-Ga₂O₃ anisotropy and SiC polarity on interface characteristics by combining different surfaces and terminations of β-Ga₂O₃ with SiC polar faces. All models exhibit type-II band alignment with valence band offsets (VBOs) larger than 1.8 eV, which is suitable for photodetector applications. Contrary to polarity expectations, most Si-face models generally exhibit VBOs larger than those of their C-face counterparts. The observed anomalies arise from unsaturated C-O bonds within the C-face's interfacial six-membered-ring structure, which introduces band edge states at the interface. Holes from the β-Ga₂O₃ side will first occupy these states before transferring to SiC, leading to greater band upward shifting at the β-Ga₂O₃ side and consequently reduced VBOs. By revealing the origin and impact of the underlying mechanisms, this work provides a theoretical basis for band engineering in β-Ga₂O₃/4H-SiC heterojunctions.

The high sulfur content and unique chain structure of VS ₄ make it a promising electrode material, while its further application is limited by the unsatisfactory Li ⁺ diffusion kinetics, structural instability, and challenges in achieving flexible energy storage. Here, a VS ₄ ‐anchored, N‐doped carbon nanofibers (N‐CNFs) network with MXene shell and surface coating is constructed, enabling durable and fast Li ⁺ storage in batteries. This flexible and self‐supported electrode demonstrates high reversible capacity (1350 mAh g ⁻¹ at 0.1 A g ⁻¹ ), excellent rate (430 mAh g ⁻¹ at 10 A g ⁻¹ ) and cycling (453 mAh g ⁻¹ after 2000 cycles at 5 A g ⁻¹ ) performance. The 3D N‐CNFs substrate, with large surface area, mechanical flexibility, and high conductivity, forms a robust interfacial bond with the anchored VS ₄ , thereby enhancing structural stability. The optimized MXene‐VS ₄ interfacial structure is revealed to enhance Li ⁺ adsorption, shorten Li ⁺ transport pathways, and effectively buffer the volume changes of VS ₄ . When paired with NCM8 ₁₁ and LFP cathodes, the flexible pouch cells exhibit high capacities and robust cycling performance under bending conditions. This strategic layered design enhances the reaction kinetics and stability of VS ₄ for Li ⁺ storage, offering a promising electrode design strategy for fast‐charging flexible batteries.

Volatile resistive switching in neuromorphic computing can be tuned by external stimuli such as temperature or electric-field. However, this type of switching is generally coupled to structural changes, resulting in slower reaction speed and higher energy consumption when incorporated into an electronic device. The vanadium dioxide (VO₂), which has near room temperature metal-insulator transition (MIT), is an archetypical volatile resistive switching system. Here, we demonstrate an isostructural MIT in an ultrathin VO₂ film capped with a photoconductive cadmium sulfide (CdS) layer. Transmission electron microscopy, resistivity experiments, and first-principles calculations show that the hole carriers induced by CdS photovoltaic effect are driving the MIT in rutile VO₂. The insulating-rutile VO₂ phase has been proved and can remain stable for hours. Our finding provides a new approach to produce purely electronically driven MIT in VO₂, and widens its applications in fast-response, low-energy neuromorphic devices.

Achieving multiple types of resistive switching in a single material with controlled ionic motion is a key challenge in neuromorphic computing, traditionally addressed by combining materials with distinct switching behaviors. Here, Cu_2‐xS is identified as a promising candidate to overcome this limitation due to its hierarchical phase transitions. Using in situ biasing experiments, reversible and non‐reversible phase transitions (and resistive switching) are demonstrated in γ‐Cu₂S by controlling the compliance current. The formation of parallel high‐digenite Cu_1.8S channels, orientated along the γ‐Cu₂S [201] crystallographic direction, drives the nonvolatile resistive switching. These channels emerge via an intermediate δ‐Cu₂S phase and are stabilized at room temperature by residual strains, alongside β‐Cu₂S phase. The work clarifies the complex, electrically triggered phase transformations in γ‐Cu₂S, and highlights the potential of Cu_2‐xS as a versatile material for neuromorphic computing.

Memristors have garnered significant attention due to their potential for multilevel storage and synaptic learning capabilities. However, the variability in forming and breaking conductive pathways in conventional memristors restricts their application in simulating neural synapses. The resistive switching in ferroelectric memristors is driven by stable ferroelectric switching, effectively avoiding the issues. Herein, we proposed a ferroelectric memristor based on yttrium-doped hafnium oxide, in which the resistive mechanism depends on the interaction between ferroelectricity and vacancies. It exhibits high on/off ratio (>10³), long retention time (>10⁴ s), stable endurance (100 cycles), and multilevel resistive memory. For information manipulation, diverse Boolean logic functions can be demonstrated, validating reconfigurable memory logic processing. Additionally, leveraging the unique properties of the memristor, an image encryption function is implemented. For neuromorphic computing, a high recognition accuracy of 96.36% is achieved for the handwritten digit data set. These results mark a significant step forward in the advancement of information processing and neuromorphic computing.