Mismatch Strain Research Articles

Regulation strategy of preparation methods for new spherical La-Y-Ni hydrogen storage alloy with ultra-long cycle lives

La-Y-Ni-based alloys are high-performance superlattice rare-earth H2-storage electrode materials. However, their complex phase structural evolution results in poor electrochemical cycle lives. In this study, a gas atomization method develops to obtain spherical La-Y-Ni-based hydrogen storage alloys with high structural stability. The spherical La-Y-Ni powder exhibits a narrow particle size distribution between 30 and 75 μm and capacity retention over 60 % for 600 cycles. A three-dimensional particle insertion strain model and finite element simulations reveal the direct effects of the particle morphology on the stress distribution during hydrogen embedding. The spherical powder exhibits a uniform strain, good mechanical properties, and resistance against pulverization and damage. The new preparation strategy for spherical powders prominently regulates the [A2B4] subunit, decreasing the subunit mismatch and lattice strain, and improving the structural stability during the hydrogen absorption/desorption. In addition, the morphology regulation, phase composition controllability, platform characteristics and electrochemical properties investigate by comparing the use of gas atomization, casting, and rapid quenching. This study provides a new direction for developing high-performance spherical electrode materials.

Synthesizing ordered polar patterns in nonpolar SrTiO3 nanofilms via wrinkle-induced flexoelectricity

Ordered polar structures in oxide nanofilms play a pivotal role in the development of nanoelectronic applications. Hitherto, ordered polar structures have been restricted to a limited number of ferroelectric materials, and there is no effective scheme to induce and manipulate ordered polar patterns in centrosymmetric nonpolar nanofilms due to the absence of spontaneous symmetry breaking. Here, we circumvent these limitations by utilizing the wrinkle-induced strain gradient modulation associated with flexoelectricity as a general means of inducing and manipulating ordered polar patterns in nonpolar nanofilms. Leveraging the surface instability caused by strain mismatch between oxide nanofilms and pre-strained compliant substrate, we successfully fabricate striped SrTiO3 wrinkles, where well-ordered strain gradients and corresponding periodic polar patterns are readily achieved. Through in-situ piezoresponse force microscopy experiments, we show that the generated polar patterns can be manipulated by varying strain boundaries. Furthermore, the atomistic resolution images and first-principles calculations reveal that such wrinkle-induced ordered polar patterns primarily emerge from the flexoelectric coupling between the local polarization and strain gradients. These findings provide implications for manipulating polar structures by strain gradient and flexoelectric engineering, which in turn enable the realization of nontrivial polar structures in a broader range of materials.

High-Performance Giant InP Quantum Dots with Stress-Released Morphological ZnSe-ZnSeS-ZnS Shell.

Indium phosphide (InP) quantum dots (QDs) are increasingly considered potent alternatives to traditional cadmium-based QDs. Notwithstanding, the material stability of InP, especially when juxtaposed with its cadmium-based counterparts, poses significant challenges in its application. Generally, a thick ZnS shell is applied to InP cores to thwart photo-oxidation and diminish nonradiative recombination. Yet, the pronounced lattice mismatch between the InP core and the ZnS shell can introduce lattice defects, consequently attenuating the luminescence efficiency. This makes the cultivation of a flawless thick shell a paramount challenge. In the present research, a synthetic methodology is elucidated to fabricate highly efficient InP QDs with dimensions exceeding 20nm, achieved by alleviating the lattice mismatch strain during the shell growth. By regulating the shell composition and morphology, InP/ZnSe/ZnSeS/ZnS QDs with shield-like morphology are prepared and demonstrate a photoluminescence quantum yield (PLQY) of ≈90%, exhibiting significantly enhanced photostability and thermal stability. This discovery is expected to greatly advance the preparation of highly efficient InP-based or other QDs, expanding their potential in various applications such as environmentally friendly displays and energy-saving lighting.

Linear strain gradient-regulated bifurcation of circular bilayer plates

Bilayer structures with controllable self-folding capability have found applications in a variety of cutting-edge fields such as flexible electrics, wearable devices and soft robotics. The folding of bilayer structures occurs when the mismatch strain between the two layers exceeds the bifurcation threshold, resulting in a deformation transition from an axisymmetric to a folded state. Previous efforts have predominantly focused on bilayer structures with uniform and/or anisotropic strain distributions. However, the role of non-uniform in-plane strain distributions in regulating the bifurcation of bilayer structures has not been fully understood. In this study, the effects of linear in-plane strain gradients on the bifurcation of circular bilayer plates, both with and without geometric mismatch, are systematically investigated by combining theoretical analysis, finite element simulations and experiments. Our results reveal that both the mismatch strain gradient and the geometric mismatch between the two layers play crucial roles in regulating bifurcation. Notably, linear mismatch strain gradients with larger strain at the center delay bifurcation, while those with larger strain along the edge promote bifurcation. This work offers new insights into the design of controllable self-folding bilayer structures, which is of great significance for advanced applications.

Study on the Mechanical Response Behavior of X80 Pipeline Steel Welding Structure under Tensile Stress

Abstract The weld joint is composed of the weld area and the heat-affected area. The heterogeneity of the organizational structure will lead to local strain mismatch and affect its mechanical properties. This paper studies the strain distribution characteristics of the weld area and the heat-affected area under tensile stress, and reveals the respective strain response mechanism of the two regions. It is found that the weld area has lower yield strength and hardness, greater uniform elongation and strain hardening index. The plastic strain of the weld joint under tensile stress is highly heterogeneous, and the strain response mechanism is mainly based on the processing hardening effect. The strain response of the heat-affected area is weak and is affected by grain-oriented hardening. The research results provide a theoretical basis and experimental basis for the design of pipeline steel welding process and the safety evaluation under plastic deformation conditions.

Differential growth-induced center waving of film-substrate system

Various intriguing morphological patterns emerge on the surfaces of growing, developing, or aging tissues, organs, and colonies of microorganisms. Our research draws inspiration from biological growth processes and applies differential growth to film-substrate systems. The strain mismatch induced by this approach leads to distinctive buckling patterns. Through a combination of finite element analysis (FEA) and theoretical analysis, we derive a comprehensive expression for the strain energy in a buckled film-substrate system subjected to differential growth. By solving the energy equations, our study investigates the intricate interplay of material properties, growth functions, and geometric characteristics. This exploration provides valuable insights into the deformations induced by growth in membrane structures and soft materials. Additionally, we establish a phase diagram that characterizes the buckling patterns. It opens avenues for innovative geometric design and 3D self-assembly techniques. Furthermore, our findings have the potential to inspire applications in fields such as soft robotics and flexible electronics.

HA antigenic variation and phylogenetic analysis of influenza B virus in Shiraz, Iran

BackgroundInfluenza infection is highly contagious respiratory illness triggered by the influenza virus, bearing substantial implications for global health. Influenza B viruses, specifically the Victoria and Yamagata lineages, have contributed to the disease burden, and the mismatch between circulating strains and vaccine strains has led to increased mortality and economic costs. Understanding the global epidemiology, seasonal variations, and genetic characteristics of influenza B is crucial for effective prevention and control strategies. MethodsThe study investigated influenza B viruses in Shiraz, Iran during the Oct 2017 to Jan 2018. Throat swabs were collected from 235 individuals under 15 with influenza-like symptoms including fever and cough. Samples were stored at -80°C and transported to the lab for further analysis. Viral RNA was extracted and analyzed using Real-time PCR. The hemagglutinin (HA) gene of positive samples was sequenced, and phylogenetic trees were constructed. Amino acids indicative of adaptive mutations were identified using global sequence data. Results23 of 235 samples (9.7 %) were positive for influenza B virus. The most common clinical manifestations were rhinorrhea and myalgia, with 20 individuals (87 % of the 23 infected people) each showing these symptoms. The phylogenetic analysis of the HA gene showed that the Victoria isolates were close to the B/Brisbane/60/2008 strain (12.5 % of the positive samples) and belonged to clade-1A, while the Yamagata isolates were close to the B/Phuket/3037/2013 strain (87.5 % of the positive samples) and belonged to clade-3. ConclusionThe study highlights the need for importance vaccine coverage in the Shiraz region to address limited genetic diversity and strain mismatch. Continuous surveillance of mutations in the HA gene resulting in amino acid substitutions and their impact on vaccine efficacy is crucial. This study showed that the circulation of influenza B in Shiraz matched with the recommended Yamagata vaccine strain. These findings contribute to the understanding of influenza B dynamics and emphasize the importance of region-specific prevention and control strategies.

Probing interfacial stress on Au cathode in DMSO electrolyte during electrochemical polarization in aprotic Li-O2 batteries

The practical performance of Li-O2 batteries suffers from interfacial instabilities associated with the reaction intermediates. These instabilities on the cathode-electrolyte interface dictate the direction of the oxygen evolution and reduction reactions (OER/ORR) in Li-O2 batteries. Despite intensive research on chemical instabilities in the reaction intermediates, there is limited work on understanding the importance of stress on the interfacial dynamics. To address this gap, in-situ curvature measurements were conducted to probe interfacial stress generation during electrochemical polarization on Au cathode in DMSO electrolytes. Charge accumulation induces tensile stress, whereas compressive stress generation is associated with the adsorbate-induced stress and mismatch strain between reaction intermediates and the Au surface. Abrupt stress relaxation on the onset of discharge presents evidence for a contribution of electrostriction stress. Adsorption of redox mediator nitrate ions induces compressive stress before ORR. Unique findings demonstrate the impact of interfacial stress on the OER/ORR in Li-O2 batteries.

Strain and piezoelectric control of electronic and photonic properties of p − n diodes

Piezoelectricity is a well-known effect in a vast number of technologically important insulators and semiconductors and exists in 20 out of the 32 three-dimensional crystal classes. The piezoelectric effect is the driving mechanism behind several classical sensors and transmitters, and also most recently, in many nanodevices. Zhong Lin Wang coined the fields piezotronics and piezo-phototronics where the piezoelectric effect plays a dominant role. Piezoelectricity couples in a linear fashion mechanical strain to electrical fields and vice versa. In solids, there is another linear coupling between strain and the electric potential, known as the deformation potential effect. While linear in its coupling nature, this effect does not require the solid to be non-centrosymmetric in contrast to the piezoelectric effect. Moreover, the deformation potential effect is quantitatively huge and leads to changes in the conduction and valence band edges of III–V and II–VI materials of, typically, 50–100 meV in the presence of 1 % strain. Therefore, the deformation potential effect is essential to determine the electronic and photonic properties of bulk and nanostructure semiconductors in the presence of strain. In this work, we compute the relative importance of piezoelectricity and the deformation potential effect in the presence of lattice mismatch and external strain. We choose p − n junctions of ZnO/GaN structures but anticipate that the general conclusions can be carried over to other material structures. The main result of the present work is that both the inclusion of the deformation potential effect and piezoelectricity is crucial to correctly compute the effect of strain on p − n junction current–voltage curves and photonic properties. In our analysis of wurtzite heterostructures, the spontaneous polarization effect is also included but this effect appears to play a minor role for electronic and photonic properties.

Antiferroelectric Ceramics for Energy-Efficient Capacitors by Theory-Guided Discovery.

Antiferroelectric ceramics, via the electric-field-induced antiferroelectric (AFE)-ferroelectric (FE) phase transitions, show great promise for high-energy-density capacitors. Yet, currently, only 70-80% energy release is found during a charge-discharge cycle. Here, for PbZrO3-based oxides, geometric nonlinear theory of martensitic phase transitions is applied (first used to guide supercompatible shape-memory alloys) to predict the reversibility of the AFE-FE transition by using density-functional theory to assess AFE/FE interfacial lattice-mismatch strain that assures ultralow electric hysteresis and extended fatigue lifetime. A good correlation of mismatch strain with electric hysteresis, hence, with energy efficiency of AFE capacitors is observed. Guided by theory, high-throughput material search is conducted and AFE compositions with a near-perfect charge-discharge energy efficiency (98.2%), i.e., near-zero hysteresis are discovered. And the fatigue life of the capacitor reaches 79.5 million charge-discharge cycles, a factor of 80 enhancement over AFE ceramics with large electric hysteresis.

Experimental Observation of a New Attenuation Mechanism in hcp‐Metals That May Operate in the Earth's Inner Core

AbstractSeismic observations show the Earth's inner core has significant and unexplained variation in seismic attenuation with position, depth and direction. Interpreting these observations is difficult without knowledge of the visco‐ or anelastic dissipation processes active in iron under inner core conditions. Here, a previously unconsidered attenuation mechanism is observed in zinc, a low pressure analog of hcp‐iron, during small strain sinusoidal deformation experiments. The experiments were performed in a deformation‐DIA combined with X‐radiography, at seismic frequencies (∼0.003–0.1 Hz), high pressure and temperatures up to ∼80% of melting temperature. Significant dissipation (0.077 ≤ Q−1(ω) ≤ 0.488) is observed along with frequency dependent softening of zinc's Young's modulus and an extremely small activation energy for creep (⩽7 kJ mol−1). In addition, during sinusoidal deformation the original microstructure is replaced by one with a reduced dislocation density and small, uniform, grain size. This combination of behavior collectively reflects a mode of deformation called “internal stress superplasticity”; this deformation mechanism is unique to anisotropic materials and activated by cyclic loading generating large internal stresses. Here we observe a new form of internal stress superplasticity, which we name as “elastic strain mismatch superplasticity.” In it the large stresses are caused by the compressional anisotropy. If this mechanism is also active in hcp‐iron and the Earth's inner‐core it will be a contributor to inner‐core observed seismic attenuation and constrain the maximum inner‐core grain‐size to ≲10 km.

4D printing of cellular silicones with negative stiffness effect for enhanced energy absorption and impact protection

Cellular silicone foams are renowned for their exceptional flexibility, ultra-elasticity, and durability, which have gained significant attention in diverse applications. However, manufacturing porous silicone foams featuring substantial bending curvatures and customized mechanical properties remains a challenge. Herein, this work presents a new strategy for manufacturing curved porous silicone foams with both 4D printed bending curvature and tailored meta-mechanical properties. The foam is achieved by direct ink writing of composite silicone inks embedded with thermal expandable microspheres as foaming agents. The work studied in detail the thermal expansion of microspheres, foaming of composite silicone inks, as well as properties of the expanded foam. Utilizing the strain mismatch under thermal stimuli, the printed bilayer structures achieved shape-shifting. Additionally, silicones composed of stacked bilayer filaments exhibited negative stiffness properties under compression, leading to enhanced energy absorption capacity, which can be fine-tuned through different printing structural designs, demonstrating its potential in fields such as energy dissipation and shock absorption while protecting objects with curved shapes.

Interfacial strain induced giant magnetoresistance and magnetodielectric effects in multiferroic BCZT/LSMO thin film heterostructures

Layered thin films of the ferroelectric perovskite Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) and the ferromagnetic half-metal La0.80Sr0.20MnO3 (LSMO) are well-known multiferroic systems that show promise for spintronic applications. In this work, the structure–property relationships are explored in novel BCZT/LSMO thin film heterostructures with optimized ferroic properties. Epitaxial BCZT/LSMO thin film heterostructures are grown by varying the lattice mismatch strains on single crystal LaAlO3 (LAO) (100) and MgO (100) substrates using the pulsed laser deposition technique. The epitaxial strain in the films gives rise to a tetragonal distortion of the BCZT and LSMO unit cells and significantly affects their magnetotransport and magnetodielectric properties. The BCZT/LSMO/LAO heterostructure exhibits a colossal magnetoresistance effect due to a large out-of-plane tensile strain, which induces enhanced carrier hopping in the LSMO layer as compared to the BCZT/LSMO/MgO film. The larger tetragonal distortion of the BCZT unit cell in BCZT/LSMO/MgO contributes to higher dielectric permittivity, with a greater dielectric maxima temperature and freezing temperature. Magnetodielectric measurements reveal a hitherto unobserved giant magnetodielectric effect in the BCZT/LSMO/MgO film, attributed to a large in-plane strain, which induces interfacial polarization distortion at the interfacial layer. Overall, this work elucidates the unique strain and charge-mediated cross-coupled phenomena of magnetic and electric orders in multiferroic thin film heterostructures, which are critical for their technological applications.

Modelling of microscopic crack initiation behaviour of fretting fatigue based on X-ray micro-computed tomography scan

Fretting fatigue is a particularly destructive form of fatigue failure that has drawn significant attention from researchers. This paper proposes a numerical modelling method based on tomography scan to investigate the impact of inclusions on fretting fatigue crack initiation behaviour. The results reveal that inclusions can affect the crack initiation direction and reduce the initiation lifetime. The difference between the properties of inclusions and matrix leads to local mechanical response mismatch, resulting in local stress, strain, and damage concentration. The mismatch in strain and damage follows a gradient distribution along the thickness as the distribution in these mechanical responses. These could explain why particles closer to the surface are more likely to cause damage. Additionally, the aggregation distribution of inclusions results in merging and connecting local regions with high stress, strain, and damage concentration, ultimately promoting fracture behaviour. Finally, the numerical models are validated with experimental data from fretting fatigue tests. Compared to the homogeneous model, the numerical model that considers inclusions from topography data can more accurately analyse the material damage and provide a more comprehensive understanding of fretting fatigue behaviour.

Within-host influenza viral diversity in the pediatric population as a function of age, vaccine, and health status.

Seasonal influenza virus predominantly evolves through antigenic drift, marked by the accumulation of mutations at antigenic sites. Because of antigenic drift, influenza vaccines are frequently updated, though their efficacy may still be limited due to strain mismatches. Despite the high levels of viral diversity observed across populations, most human studies reveal limited intrahost diversity, leaving the origin of population-level viral diversity unclear. Previous studies show host characteristics, such as immunity, might affect within-host viral evolution. Here we investigate influenza A viral diversity in children aged between 6 months and 18 years. Influenza virus evolution in children is less well characterized than in adults, yet may be associated with higher levels of viral diversity given the lower level of pre-existing immunity and longer durations of infection in children. We obtained influenza isolates from banked influenza A-positive nasopharyngeal swabs collected at the Children's Hospital of Philadelphia during the 2017-18 influenza season. Using next-generation sequencing, we evaluated the population of influenza viruses present in each sample. We characterized within-host viral diversity using the number and frequency of intrahost single-nucleotide variants (iSNVs) detected in each sample. We related viral diversity to clinical metadata, including subjects' age, vaccination status, and comorbid conditions, as well as sample metadata such as virus strain and cycle threshold. Consistent with previous studies, most samples contained low levels of diversity with no clear association between the subjects' age, vaccine status, or health status. Further, there was no enrichment of iSNVs near known antigenic sites. Taken together, these findings are consistent with previous observations that the majority of intrahost influenza virus infection is characterized by low viral diversity without evidence of diversifying selection.

Phase field modeling of grain stability of nanocrystalline alloys by explicitly incorporating mismatch strain

Phase field modeling of grain stability of nanocrystalline alloys by explicitly incorporating mismatch strain

Effect of thermal mismatch strain on the self-assembly of nanorods in YBCO/NRs nanocomposite films

This study presents a thermoelastic model to investigate the impact of thermal mismatch strain, resulting from distinct thermal expansion coefficients between the film matrix and nanorods, on the self-assembly of nanorods in YBCO/NRs nanocomposite films. An accurate understanding of thermal mismatch strain generated during nanocomposite film preparation is vital for controlling the self-assembly of artificial nanorods in such films. In this model, we calculated the total elastic energy density of the film matrix and nanorods, considering both lattice and thermal mismatch strains, to analyze the effect of thermal strain on the diameter of c-oriented nanorods in YBCO nanocomposite films. The calculated nanorod diameter values match experimentally measured values for BaZrO3 and BaSnO3 nanorods. Furthermore, compared to results that only consider lattice mismatch strain, the proposed model yields closer calculation values to experimental measurements by incorporating the impact of thermal mismatch strain. The thermal mismatch strain also affects the spacing between two adjacent nanorods, having the most profound effect on BSO nanorods compared to BZO and BHO nanorods. These findings contribute to understanding the mechanisms involved in nanorod self-assembly and provide insights to optimize the design of YBCO/NRs nanocomposite films.

Enhancing oxygen reduction reaction performance through eco-friendly chitosan gel-assisted molten salt strategy: Small NiCo alloy nanoparticles decorated with high-loading single Fe-NX

We developed an effective and eco-friendly strategy using chitosan gel-molten salt to achieve high loading (2.23 At. %) of single Fe-NX as assistive active sites. These sites were combined with small NiCo alloy NPs distributed on porous carbon aerogels to boost the ORR performance. The FeSAs-NiCo alloy@N-C sphere exhibits exceptional mass activity and specific activity of 3.705 A.mg−1 and 8.79 mA.cm−2(ECSA), respectively, at 0.85 V versus RHE. It has a superior onset potential of 1.08 V versus RHE, surpassing that of its nanoparticle Fe counterpart and NiCo alloy@N-C sphere. The significant improvement in ORR performance of the FeSAs-NiCo alloy@N-C sphere could be attributed to the positive effects of increased lattice strain due to the single atoms of Fe-NX hybridized with small NiCo alloy NPs. The chitosan gel-assisted molten salt strategy and assistive active sites of Fe-NX hybridized with NiCo alloy NPs regulate the electronic properties of the FeSAs-NiCo alloy@N-C sphere, both geometrically via lattice strain mismatch and electronically through shifting of the d-band center. This could influence the binding energies for oxygen and/or oxygen reduction intermediate adsorption/desorption. The additional improvement in the ORR performance of the FeSAs-NiCo alloy@N-C sphere also benefits from having a lower electrochemical activation energy.

Anisotropic dynamic compression response of an ultra-high strength steel fabricated by laser hybrid additive manufacturing

Directed energy deposition (DED) is a technological innovation revolutionizing in-situ repair, hybrid manufacturing, and multi-material integration manufacturing, characterized by microstructural heterogeneity on a macro-scale. However, the overall performance of these DED-fabricated components under dynamic loading, particularly along different directions, remains uncharted. This work explores the anisotropic dynamic compression response of an ultra-high strength steel, namely 35CrMnSiA steel, fabricated using DED on a wrought substrate. The laser hybrid additive manufactured samples were subjected to split Hopkinson pressure bar testing along different directions. The results show the following: 1) hybrid manufactured 35CrMnSiA steel has an anisotropic dynamic compression response due to the mismatched properties of each subzone induced by microstructural heterogeneity, 2) low-strength DED part shows higher strain under compression along the build direction but behaves similarly to the wrought material when compressed along the transverse direction, 3) intergranular void/crack is the primary damage mechanism, cracks preferred formed in wrought substrate due to the martensite with poor plastic dissipation ability, 4) when the interface is subjected to parallel directional impact loads, the strain mismatch between the two side subzones leads to interface separation. This study provides comprehensive understanding of the dynamic behavior of DED-fabricated components with heterogenous microstructure, and new insight into demanding tailored strategies to ensure consistent and predictable behavior under various loading conditions.

Waterproof, stretchable and wearable corrugated conductive carbon fiber strain sensors for underwater respiration monitoring and swimming instruction

Respiration is one of crucial vital signs, which can be used for health assessment and sports management. Flexible resistive strain sensors provide an opportunity to monitor personal respiratory behaviors in real time due to high sensitivity, good linearity and fast response. However, there are some critical issues with the resistive strain sensor, such as strain mismatch, poor contact properties and moisture sensitivity, which easily cause unexpected electrical response, limiting its application scenarios. Here, a novel stretchable carbon fiber strain sensor is developed by a simple structural design, which endow the device with a remarkable linearity (R2=0.99601 in 0–40 % tensile strain), excellent anti-jamming performance, long-term durability, and waterproofness. Moreover, a sophisticated wearable respiratory monitoring system is further developed, which can not only precisely distinguish diverse respiratory patterns to enhance the accuracy in early illness diagnosis but also remotely capture real-time breathing information during swimming for guiding swimming training. It demonstrates that our stretchable resistive strain sensor has an enormous application potential in wearable electronics and smart clothing for health monitoring and training guide.