A fully hierarchical martensitic microstructure is the common feature of additively manufactured α-type Ti alloys due to the rapid cooling rate inherent to the fabrication process. However, how this hierarchy governs defect formation within α laths under cyclic thermal loadings remains poorly understood. Here, we present a systematic electron microscopy investigation of a Ti-6Al-4V fabricated by laser powder-bed fusion. The as-fabricated microstructure consists of fine α′ martensite organised into multilevel lath hierarchies inherited from prior β grains. Deformation twinning is found to be strongly dependent on the martensitic hierarchy. Two types of twins are identified based on their thickness and interactions with martensitic laths. Twins that link to the endpoints of fine martensitic plates laths, i.e., linked twins, are consistently thicker than non-linked twins within lath interiors. Such twin structures enhance the room temperature tensile performance, enabling a simultaneous improvement in tensile strength, ductility, and work-hardening capability. These results demonstrate that hierarchical martensite actively governs twin formation in additively manufactured Ti alloys, elucidating the microstructural origin of their superior mechanical properties and providing guidance for microstructural optimization.

Zinc (Zn) alloys are promising candidates for biodegradable medical applications. Their in-service performance depends critically on mechanical properties, particularly strain hardening/softening driven by grain boundary (GB) characteristics. Since the c/a ratio of hexagonal close-packed (HCP) Zn exceeds 1.8, classical interatomic potentials fail to accurately capture GB energetics and structures. In this work, a machine-learning Deep Potential (DP) model for Zn was developed. Using DP molecular dynamics (DeePMD), the energetics and structures of $ {<}11 \overline{2} 0{>} $ symmetrical tilt grain boundaries were analyzed across the full range of tilt angles (2θ = 0°~180°). Two distinct energy plateaus with minor oscillations were observed for 2θ in the ranges of 10°~90° and 96°~170°. Subsequently, DeePMD tensile simulations on the $ {<}11 \overline{2} 0{>} $ columnar grained (2D) Zn were performed to link GB energetics to plastic responses, revealing that grain rotation is the dominant plastic mechanism, facilitated by the observed energy plateaus and accompanied by limited basal dislocation activity. This grain-rotation-mediated plasticity was further confirmed by DeePMD in nanopolycrystalline (3D) Zn under tension, distinct from HCP Mg (c/a ≈ 1.63), which is dominated by multi-mode dislocations and twinning, and Be (c/a ≈ 1.52), where basal dislocations prevail. These findings highlight GB features as critical factors controlling plasticity and provide a theoretical foundation for designing nextgeneration biomedical alloys via crystallographic tailoring.

Two-dimensional (2D) fullerene (C₆₀) films grown on various metal and semiconductor substrates have been extensively studied but remain less explored on oxide substrates. By using cryogenic scanning tunneling microscopy and spectroscopy (STM/STS), we investigated the molecular orientation and electronic structure of C₆₀ films grown on a SrTiO₃(001) surface. Our STM/STS results display the variation of electronic energy levels of C₆₀ molecules as a function of both coordination and potassium doping. The orientation of each C₆₀ molecule can be identified through density-functional theory (DFT) calculations and STM simulations. The orientational assembly of the C₆₀ layer near a K-doped C₆₀ shows a chiral 2×2 superstructure of the hexagon-faced up (H) configuration. Intriguingly, the spatial distribution of the density of states (DOS) peak around the K-doped C₆₀ shows an electronic state in the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap that can be attributed to the charge-trapped state. The spatial dependence of this state indicates an upward-bending of the conduction band, induced by the screened electric field of a negatively charged center. Together, the band-bending behavior and the related chiral 2×2 superstructure suggest a possible scenario of a charge-trapped, orientational C₆₀ assembly.

High-resolution transmission electron microscopy (HRTEM) is indispensable for atomic-scale characterization yet fundamentally limited by the inherent phase loss in conventional detectors including CCD. To overcome this barrier, we propose Wave-Reconstruction Generative Adversarial Networks (WRGAN) that directly predict wave function amplitude and phase from single HRTEM images. Our physics-guided framework employs a Unet++ generator within a Generative Adversarial Networks (GAN) architecture via defining a physics-guided consistency loss. A key advantage is that WRGAN, trained solely on simulated data, demonstrates robust performance when directly applied to experimental images. Validation on experimental Nb₈W₉O₄₇ image shows predicted amplitudes and phases closely match the groundtruth wave functions. Significantly, WRGAN successfully resolves upper and lower surface projections in noisy single-wall carbon nanotube (SWCNT) images, enabling near-atomic-resolution 3D reconstruction.

Piezocatalysis facilitates the transduction of mechanical energy into chemical redox processes, but its practical application is hindered by intrinsically low catalytic efficiency and complex catalyst fabrication. Herein, we employ high-energy ball milling (HBM) to convert bulk lead-free Sr_0.5Ba_0.5Nb₂O₆ (SBN) ceramics into nanoscale piezocatalysts (SBN-HBM) with enhanced activity, and integrate them with peroxymonosulfate (PMS) activation to promote reactive oxygen species generation, thereby boosting overall catalytic performance. HBM refines grain size from the microscale to ~240 nm and introduces abundant oxygen vacancies, enhancing both piezoelectric polarization and surface reactivity. Under mechanical excitation, the integrated SBN-HBM/PMS system triggers synergistic oxidation featuring hydroxyl radicals (•OH), sulfate radicals (SO₄^•-), and piezo-induced holes, resulting in markedly accelerated degradation kinetics (e.g., k = 0.520 min^-1 for methyl orange, 0.356 min^-1 for tetracycline) and achieving > 99% bacterial inactivation. Experimental results and theoretical analyses reveal that defect-polarization coupling critically governs carrier separation dynamics and facilitates efficient redox reactions. This work offers a green and scalable strategy for transforming bulk piezoceramics into highly efficient piezocatalysts for decentralized wastewater treatment.

The polytetrafluoroethylene (PTFE) binder-based roll-to-roll dry coating process has emerged as a promising alternative to conventional slurry-based methods for fabricating thick electrodes in high-energy-density lithium-ion batteries (LIBs). However, applying nano-sized lithium iron phosphate (LiFePO₄, LFP) to this process remains challenging, as the high specific surface area of nano-sized LFP leads to the formation of short and thin PTFE fiber network that cannot ensure the mechanical integrity of dry cathode at low PTFE binder content. Consequently, the nano-sized LFP dry cathode suffers from poor flexibility and mechanical brittleness, limiting its applicability in roll-to-roll processing. In this study, we investigated the fibrillization behavior of PTFE binders depending on the particle size of LFP, to elucidate the origin of mechanical degradation in nano-sized LFP dry cathodes. Our results revealed that nano-sized LFP facilitates excessive PTFE fibrillization, generating fragile and weak networks with short and long PTFE fibers, leading to the mechanical degradation of nano-sized LFP dry cathodes. To address this issue, we introduced a two-step extrusion process that promotes the formation of thick and long PTFE fiber networks within nano-sized LFP dry cathodes. This strategy enabled the fabrication of flexible and mechanically robust nano-sized LFP cathode film with only 2 wt% PTFE binder. The developed LFP dry cathodes exhibited excellent compatibility with thick electrode designs and achieved high areal capacities (7 mAh cm^-2, 2.7 g/cc), offering a scalable solution for next-generation LFP-based LIBs.

Lithium niobate (LiNbO₃) is a key material in photonics and optoelectronics, valued for its ferroelectric, electro-optic, and nonlinear optical properties. Despite its high Curie temperature and significant spontaneous polarization, which are advantageous for light modulation and frequency conversion, undoped LiNbO₃ suffers from intrinsically weak luminescence, thereby restricting its application in light-emitting devices. Doping with rare earth ions such as erbium (Er³⁺), neodymium (Nd³⁺), and praseodymium (Pr³⁺) significantly enhances its luminescent properties by introducing efficient photon-emitting energy levels. This review provides a comprehensive overview of the luminescent properties of pure and doped LiNbO₃, with a particular focus on doping and co-doping strategies using rare earth and transition-metal ions to enhance their photoluminescence efficiency, thermal stability, and spectral tunability. The roles of dopant site occupancy, defect engineering, and charge compensation mechanisms are discussed in detail. Co-doping approaches are highlighted as promising routes to synergistically tailor emission characteristics and mitigate concentration quenching. Furthermore, the review explores recent advances in LiNbO₃-based luminescent devices, including waveguide-integrated photonic components, resonators, and thin films. Finally, future challenges and perspectives are outlined for the rational design of high-performance LiNbO₃-based luminescent materials in next-generation photonic technologies.