Enhancing the Humidity Sensitivity of Ga2O3/SnO2 Core/Shell Microribbon by Applying Mechanical Strain and Its Application as a Flexible Strain Sensor

The humidity sensitivity of a single β‐Ga₂O₃/amorphous SnO₂ core/shell microribbon on a flexible substrate is enhanced by the application of tensile strain and increases linearly with the strain. The strain‐induced enhancement originates from the increase in the effective surface area where water molecules are adsorbed. This strain dependence of humidity sensitivity can be used to monitor the external strain. The strain sensing of the microribbon device under various amounts of mechanical loading shows excellent reliability and reproducibility with a gauge factor of ?41. The flexible device has high potential to detect both humidity and strain at room temperature. These findings and the mechanism involved are expected to pave the way for new flexible strain and multifunctional sensors.     

BaTiO3/CoFe2O4/BaTiO3复合磁电薄膜生长及应力研究

用激光分子束外延（LMBE）设备,在SrTiO3（001）基片上外延生长BaTiO3/CoFe2O4/BaTiO3多层复合磁电薄膜结构。通过反射式高能电子衍射（RHEED）对薄膜生长过程进行原位监测,结果显示,随着CoFe2O4厚度的增加薄膜内应力逐渐被释放,并且应力释放的过程导致了薄膜生长模式的变化。高分辨X射线衍射（XRD）发现,随着CoFe2O4厚度的增加,CoFe2O4对BaTiO3薄膜的张应力逐渐增大,BaTiO3晶胞的c轴晶格常数逐渐变小。理论计算给出了BaTiO3面外晶格常数c随CoFe2O4沉积时间的变化规律。原子力显微镜（AFM）对表面形貌进行表征,进一步证明了复合薄膜生长模式的变化。     

Strain analysis of photocatalytic TiO2 thin films on polymer substrates

Titania (TiO₂) thin films have been deposited on polymer sheets by magnetron sputtering at room temperature. Previous X-ray diffraction experiments revealed, for a wide range of deposition parameters, that the as-deposited titania thin films are predominantly amorphous; however, Raman scattering experiments revealed small traces of crystalline phases. The photocatalytic behaviour of the titania coatings was determined by combined ultra-violet (UV) irradiation and absorption measurements of a chosen dye (pollutants) in the presence of this catalyst. In order to assess the mechanical behaviour of the as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile testing machine. As the system was stretched, cracks transverse to the loading direction developed in the film. The number of cracks increased as the applied strain increased, thus the relation between the measured crack density and the applied strain has been used to characterize the film strength and has also been correlated with the film photocatalytic efficiency. As a result of moderate fissuring on the titania film, it was found that for strain deformations up to 5% the photocatalytic activity is enhanced due to the exposure of more catalyst surface area for the pollutant to be adsorbed and subsequently dissociated upon UV illumination.     

Heterointerface and Tensile Strain Effects Synergistically Enhances Overall Water-Splitting in Ru/RuO2 Aerogels

Designing robust electrocatalysts for water-splitting is essential for sustainable hydrogen generation, yet difficult to accomplish. In this study, a fast and facile two-step technique to synthesize Ru/RuO₂ aerogels for catalyzing overall water-splitting under alkaline conditions is reported. Benefiting from the synergistic combination of high porosity, heterointerface, and tensile strain effects, the Ru/RuO₂ aerogel exhibits low overpotential for oxygen evolution reaction (189 mV) and hydrogen evolution reaction (34 mV) at 10 mA cm⁻², surpassing RuO₂ (338 mV) and Pt/C (53 mV), respectively. Notably, when the Ru/RuO₂ aerogels are applied at the anode and cathode, the resultant water-splitting cell reflected a low potential of 1.47 V at 10 mA cm⁻², exceeding the commercial Pt/C||RuO₂ standard (1.63 V). X-ray adsorption spectroscopy and theoretical studies demonstrate that the heterointerface of Ru/RuO₂ optimizes charge redistribution, which reduces the energy barriers for hydrogen and oxygen intermediates, thereby enhancing oxygen and hydrogen evolution reaction kinetics.     

Bioinspired Dual-Mode Stretchable Strain Sensor Based on Magnetic Nanocomposites for Strain/Magnetic Discrimination

Recently, flexible stretchable sensors have been gaining attention for their excellent adaptability for electronic skin applications. However, the preparation of stretchable strain sensors that achieve dual-mode sensing while still retaining ultra-low detection limit of strain, high sensitivity, and low cost is a pressing task. Herein, a high-performance dual-mode stretchable strain sensor (DMSSS) based on biomimetic scorpion foot slit microstructures and multi-walled carbon nanotubes (MWCNTs)/graphene (GR)/silicone rubber (SR)/Fe₃O₄ nanocomposites is proposed, which can accurately sense strain and magnetic stimuli. The DMSSS exhibits a large strain detection range (≈160%), sensitivity up to 100.56 (130–160%), an ultra-low detection limit of strain (0.16% strain), and superior durability (9000 cycles of stretch/release). The sensor can accurately recognize sign language movement, as well as realize object proximity information perception and whole process information monitoring. Furthermore, human joint movements and micro-expressions can be monitored in real-time. Therefore, the DMSSS of this work opens up promising prospects for applications in sign language pose recognition, non-contact sensing, human-computer interaction, and electronic skin.     

Strain and stress build-up in He-implanted UO2 single crystals: an X-ray diffraction study

The strain and stress build-up in 20-keV He-implanted UO₂ single crystals have been determined by means of X-ray diffraction through reciprocal space mapping, with the use of a model dedicated to the analysis of the strain/stress state of ion-irradiated materials. Results indicate that the undamaged part of the crystals exhibits no strain or stress; on the other hand, the implanted layer undergoes a tensile strain directed along the normal to the surface of the crystals and a compressive in-plane stress. The build-up of both strain and stress with He fluence exhibits a two-step process: (i) a progressive increase up to a maximum level of ~1% for the strain and ~−2.8 GPa for the stress, followed by (ii) a dramatic decrease. The origin of the strain and stress build-up is the formation of both self-interstitial defects and small He-vacancy clusters. The strain, and stress relief is tentatively attributed to the formation of extended defects (such as dislocations) that induce a plastic relaxation.     

Numerical Studies of Thermally Induced Residual Strain/Stress in Bi2Sr2Ca2Cu3O x /Ag/Ag Alloy Composite Tapes and the Dependence of Material Properties on the Temperature

Thermally induced residual strain/stress in Bi₂Sr₂Ca₂Cu₃O _x (Bi2223)/Ag/Ag alloy composite tapes and the dependence of material properties on the temperature have been studied numerically. Based on both the straight and bending 3D tape models, and with the temperature dependence on material properties (especially the coefficient of thermal expansion) among the constituents (Bi2223, Ag and Ag alloy sheath) of Bi2223 multifilament composite tapes, the residual strain accumulation and the distribution of the residual stress have been obtained. We found that by taking account of the temperature dependence on material properties of Bi2223 composite tapes the residual strain in the current transportation direction is up to 15 % larger than that without taking temperature dependence into account. Furthermore, by considering the distribution of the stress induced from the changing temperature, we analyzed the mechanical strength of Bi2223 composite tapes and concluded that the initial mechanical failure due to large temperature circle (intrinsically induced from the mismatch of the coefficient of thermal expansion of each constituent in composite tapes) comes from the following aspects: (i) the tensile fracture in the Bi2223 filaments occurring at the center of the tape and (ii) the delamination most likely arising at the interface between the Bi2223 filaments and Ag matrix near both edges of the cross-section of the tape, which originates at the Bi2223 side of the interface.     

C/C复合材料压缩破坏的应变率效应研究

研究了碳布叠层/碳复合材料在四种不同应变率下的压缩性能, 对其在准静态、动态载荷下的压缩破坏机理进行了初步的探讨. 研究结果表明: C/C复合材料的压缩破坏强度具有较强的应变率效应, 与准静态(10^-4/s)相比, 复合材料的动态(1.5×10²/s)压缩强度可提高70%左右; 复合材料在准静态、动态载荷下力学性能的差异可归结为纤维与基体界面特性的应变率效应以及不同应变率下破坏模式的不同.     

Strain rate sensitivity of glass/epoxy composites with nanofillers

It is understood that small amount of nanoclay in the neat epoxy and fiber reinforced epoxy composite system improves the mechanical properties. The mechanical properties of most of polymer matrix composites are rate sensitive. Most of the researches have concentrated on the behavior of the polymer composites at high strain rates. The present research work is to study the effect of clay on neat epoxy and glass/epoxy composites, at low strain rates. The clay in terms of 1.5, 3 and 5 wt% are dispersed in the epoxy resin using mechanical stirrer followed by sonication process. The glass/epoxy nanocomposites are prepared by impregnating the glass fiber with epoxy–clay mixture by hand lay-up process followed by compression molding. Characterization of the nanoclay is done by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Tensile stress–strain curves are obtained at strain rates of 10⁻⁴, 10⁻³, 10⁻² and 10⁻¹ s⁻¹ by a servo-hydraulic machine and the variation of modulus, strength and failure strain with strain rate are determined. The results show that, even at low strain rates, the longitudinal strength and stiffness increase as strain rate increases for all clay loadings. It is observed that the tensile modulus increases as the clay loading increases for both epoxy and glass/epoxy nanocomposites. Scanning electron microscopy is used to study the adhesion of composites in fracture surfaces.     

Stress and Strain in Perovskite/Silicon Tandem Solar Cells

<正>Tandem solar cells based on metal halide perovskites are advancing rapidly during last few years [1–17]. The certified power conversion efficiency(PCE) for monolithic perovskite/silicon tandem solar cell reaches 32.5%[18]. Since tandem solar cells contain more layers than single-junction solar cells, stress/strain control is an issue during fabrication and further practical operation.     

异质外延MgO/SrTiO3薄膜中界面应力研究

本文利用激光分子束外延(LMBE)技术在SrTiO3(100)单晶基片上外延生长MgO薄膜，同时又在MgO(100)单晶基片上外延生长SiO3(STO)薄膜。通过反射高能电子衍射(RHEED)仪原位实时监测薄膜生长，研究薄膜的生长过程。并结合X射线衍射(XRD)仪来分析在不同的生长条件下，不同应力对薄膜外延生长的影响。在压应力情况下，MgO薄膜在STO基片上以单个晶胞叠层的方式生长，即以“Cubicon Cubic”方式进行外延；在张应力情况下，由于膜内位错较多，STO薄膜在MgO基片上以晶胞镶嵌的方式进行生长，即以“Mosaic”结构进行外延；提高生长温度，可以减少膜内位错，提高外延质量，使STO薄膜在MgO基片上以较好的层状方式外延生长。     

Strain Localisation in iPP/MWCNT Nanocomposites Using Digital Image Correlation

Polypropylene/multiwall carbon nanotube nanocomposites with different rates of weight incorporation (0–1%) were prepared by melt compounding and cast extrusion. The effect of maleic anhydride (5 wt%) grafted on polypropylene is studied through mechanical tests at different scales and morphological observations. In particular, the micromechanism of deformation was investigated through instrumented tensile experiments (at a macro and micro scales) using of a non‐contact method known as digital image correlation. The objective of this paper is first to characterise global behaviour (Young modulus, tensile strength, and ultimate properties) and second to go further in local analysis. In particular, optical instrumentation enables estimation of strain profile distribution onto the sample in a constricted area. Statistical parameters extracted from these local profiles are promising tools to enhance mechanical properties in link with microstructural composition. Tensile tests confirm composite reinforcement at a low level of nanocomposite incorporation, and local analysis enables quantitative measurements of adding maleic anhydride in formulations. The results reveal that addition of maleic anhydride delays strain localisation in the necked area.     

Strain distribution in freestanding Si/SixNy membranes studied by transmission electron microscopy

Strain was induced in a bridge-shaped freestanding Si membrane (FSSM) by depositing an amorphous Si_xN_y layer to surround the Si membrane. Convergent beam electron diffraction revealed that compressive strain is distributed uniformly along the horizontal direction in Si_xN_y-deposited FSSM. On the other hand, strain decreases to almost zero at the ends of the FSSM, where the Si_xN_y layer beneath the Si layer is replaced by a SiO₂ buried oxide layer.     

纳米银-聚合物菱形剪纸薄膜应变传感特性的研究

采用银镜制备法和激光切割技术获得了纳米银颗粒/聚二甲基硅氧烷剪纸结构薄膜,并系统地研究了薄膜作为柔性应变传感器的力学及压阻特性。将数值模拟与实验相结合,测量了传感薄膜的应变比γ、压阻滞回特性、线性度及压阻敏感性,重点探讨了薄膜制备工艺、结构参数与上述薄膜传感特性的定量关系。结果表明,在给定结构下,结构薄膜整体与结构单元的应变比γ为常数,反映了结构薄膜的变形特性,是理想的力学性能表征参数。菱形剪纸结构薄膜具有量级可达200的大应变比,即在大应变下,材料的实际应变很小。这一特点极大地提升了薄膜的应变测量范围、压阻稳定性、线性度,并保持了合理的压阻灵敏度。     

PC/ABS在高应变率下的压缩大变形

目的对PC/ABS在高应变率下的压缩大变形行为进行实验研究与模拟。方法在应变率为1600~5000 s~(-1),温度为293~353 K的范围内,选用霍普金森压杆获取其在高应变率、高温下的大变形行为;选用DSGZ本构模型,模拟PC/ABS在高应变率下的大变形。结果 PC/ABS大变形行为强烈依赖于应变率和温度,屈服应力随应变率增加或温度降低而升高,大变形行为包括弹性、屈服、应变软化和应变硬化。结论DSGZ本构可准确模拟PC/ABS在高应变率、高温下的大变形行为。     

Strain engineering in single-, bi- and tri-layer MoS2, MoSe2, WS2 and WSe2

Nano Research - Strain is a powerful tool to modify the optical properties of semiconducting transition metal dichalcogenides like MoS2, MoSe2, WS2 and WSe2. In this work we provide a thorough...     

应力补偿技术在InAs/GaAs量子点中的研究现状

通过在多层量子点体系中引入应变补偿层,改变量子点系统的应力场分布,可以控制生长过程中量子点的大小均匀性和密度,最终获得高质量、高密度的多层量子点体系,应用到量子点光电器件中,可改善器件的电学和光学性能。介绍了应变补偿层在量子点体系中作用的原理,常用的应变补偿材料体系,以及目前国内外对应变补偿技术的研究状况,最后提出了现存的问题和今后的发展方向。