Acta Energiae Solaris Sinica•2026•DOI: 10.19912/j.0254-0096.tynxb.202608_9719
Fixed alarm thresholds in wind turbine gearbox bearing monitoring rely on manual experience and fail to adapt to non-stationary operating conditions, causing false and missed alarms. This paper proposes an adaptive threshold algorithm, EWMA-Bi-DSPOT, combining exponentially weighted moving average (EWMA) smoothing with bilateral drift streaming peaks-over-threshold (POT) modeling. The method operates in two stages: initialization and online update. In initialization, EWMA suppresses high-frequency noise in raw SCADA temperature sequences; a high quantile is selected as an initial threshold, and a generalized Pareto distribution (GPD) is fitted to exceedances via maximum likelihood estimation to obtain an initial alarm threshold. In the online stage, the algorithm continuously absorbs marginal extreme values that do not trigger alarms, recursively updating GPD parameters and the alarm threshold to track system state drift. Experiments on a 1.5 MW doubly-fed wind turbine gearbox bearing temperature dataset demonstrate that EWMA-Bi-DSPOT achieves a false alarm rate of 3.2% and a missed alarm rate of 3.1%, outperforming comparison models. The algorithm enables dynamic adaptive threshold updates, improving real-time fault warning reliability while maintaining low false and missed alarm rates. The results confirm that EWMA filtering effectively suppresses random fluctuations and improves extreme value structure, and the bilateral extreme value update mechanism solves the inability of a single threshold to follow operating condition drift.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4499-9
Two-dimensional (2D) ferroelectric materials have emerged as promising candidates for next-generation non-volatile memory and neuromorphic computing, yet their integration into commercial devices faces substantial hurdles. This review critically examines the structure, properties, and applications of ferroelectric 2D In-Se materials, with a focus on their potential to overcome the scaling and retention limitations of conventional ferroelectrics such as Hf0.5Zr0.5O2 (HZO). The manuscript synthesizes recent advances in In-Se ferroelectricity, including the mechanisms of polarization switching, modulation strategies, and device demonstrations. Key experimental benchmarks from the literature are analyzed, such as the high data retention and read endurance of 5-nm HZO ferroelectric FETs (IEEE Electron Device Lett, 2019, 40(3): 399-402) and the giant barrier height modulation in ferroelectric van der Waals heterojunctions (Nat Electron, 2020, 3: 466-472). The review also highlights the performance of sliding ferroelectric memories based on rhombohedral-stacked bilayer MoS2, which achieved non-volatile storage with low power consumption (Nat Commun, 2024, 15: 10796). Despite these advances, critical challenges remain: the scalability of In-Se synthesis, the control of domain dynamics at the nanoscale, and the cost parity with silicon-based technologies. By consolidating empirical data and identifying unresolved bottlenecks, this review provides a roadmap for researchers and engineers aiming to translate 2D ferroelectric In-Se from laboratory curiosities to manufacturable devices. The analysis underscores the need for standardized metrology and accelerated lifetime testing to validate industrial viability.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3625-3
Zirconia (ZrO2)-based fluorite ferroelectric materials are promising for nonvolatile memory and logic devices due to their CMOS compatibility and cost advantages over hafnium oxide (HfO2). However, the metastable nature of the ferroelectric orthorhombic phase (o-phase) hinders practical application. Here, we report the strain-mediated stabilization of the ferroelectric o-phase in ZrO2 thin films grown on niobium-doped strontium titanate (NSTO) substrates with different crystallographic orientations via chemical solution deposition. Systematic structural and ferroelectric characterization, combined with simulation, reveals that substrate orientation controls in-plane tensile strain, selectively promoting epitaxial growth of the o-phase. The ZrO2 film on NSTO(110) exhibits the highest o-phase content, achieving a remanent polarization (2Pr) of 92.64 μC/cm², which remains as high as 88.54 μC/cm² after resistive-capacitive (RC) delay calibration. The device shows endurance of approximately 10^7 cycles with favorable fatigue characteristics. X-ray absorption spectroscopy (XAS) further indicates distortion of Zr-O tetrahedra, providing microscopic insight into the ferroelectricity. This work presents a novel strategy for property tuning of ZrO2 films and supports their application in storage and logic devices.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3710-y
Layered transition metal oxide cathodes for sodium-ion batteries (SIBs) suffer from Jahn–Teller distortion of MnO6, Na+/vacancy ordering, and irreversible lattice oxygen loss, causing capacity fading and voltage decay. Here, we report a P2-type material, Na0.67Ni0.3Mn0.6Li0.09Sn0.01O2 (NNMO-Li0.09Sn0.01), co-doped with closed-shell Li+ and Sn4+ ions. Li+ increases the Mn4+/Mn3+ ratio, mitigating Jahn–Teller distortion, and disrupts Ni/Mn ordering, suppressing Na+/vacancy ordering. Sn4+ forms stronger Sn–O bonds (548 kJ mol−1), enhancing bonding between transition metal ions and oxygen, reducing oxygen loss. NNMO-Li0.09Sn0.01 delivers a specific capacity of 90.3 mAh g−1 with 62.9% capacity retention after 50 cycles at 0.1 C (1 C = 200 mA g−1), and 90.3% voltage retention. This closed-shell substitution strategy offers a viable approach for enhancing structural stability of wide-voltage layered oxide cathodes.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4126-0
Flexible X-ray detectors are constrained by the difficulty of producing semiconductor films that simultaneously exhibit uniform morphology, high crystallinity, and mechanical robustness. Here, we introduce a hydrogen-bond engineered supramolecular (HBES) strategy to overcome these limitations in supramolecular bismuth halide clusters (PDBiI5). By incorporating polyacrylic acid (PAA), a dynamic supramolecular network is formed that suppresses the coffee-ring effect during ultrasonic spray-coating via increased solution viscosity and controlled kinetic balance between solvent evaporation and solute diffusion. The HBES approach also modulates crystallization kinetics, extending crystal growth time from 23 to 41 s, yielding densely packed films with enhanced crystallinity and reduced defect states. These improvements lead to superior charge transport: a hole mobility of 2.16 cm2 V−1 s−1 and a mobility-lifetime product of 9.1 × 10−4 cm2 V−1. The resulting X-ray detectors achieve a record sensitivity of 19,009 μC Gyair−1 cm−2 and an ultralow detection limit of 3.35 nGyair s−1, with excellent operational and environmental stability. Leveraging the mechanical robustness from the supramolecular network, we demonstrate the first direct-type flexible X-ray imager, retaining 85% performance after 1000 bending cycles. This imager overcomes geometric distortion and vignetting, maintaining 85% edge photocurrent versus 58% for rigid detectors, enabling clear imaging of curved objects. This work establishes a versatile supramolecular engineering paradigm for high-performance flexible X-ray detection and imaging.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-4173-x
Ferroelectric memory, with its promise of low power consumption, high writing speed and exceptional endurance, requires the scaling of ferroelectric films to ultrathin dimensions—often just a few atomic layers thick. However, such extreme thinning risks destabilizing or even erasing electric polarization, mainly due to the detrimental depolarization field. Remarkably, certain ferroelectrics exhibit an intrinsic immunity to this effect, as predicted theoretically and confirmed experimentally. Examples include improper ferroelectrics, hyper ferroelectrics, engineered heterostructures, and low-dimensional van der Waals ferroelectrics. This review systematically examines these unique materials, unravelling the fundamental physics behind their polarization robustness and the mechanisms enabling them to resist the depolarization field. By bridging theory with experimental advances, we aim to inspire the design of next-generation ferroelectrics capable of overcoming critical challenges encountered in practical ferroelectric memory devices.