Buckled Structure Research Articles

Entanglement harvesting in buckled honeycomb lattices by vacuum fluctuations in a microcavity

We study the entanglement harvesting between two identical buckled honeycomb lattices placed inside a planar microcavity. By applying time dependent perturbation theory, we obtain quantum correlations between both layers induced by the cavity field. Considering the vacuum state as the initial state of the cavity field and tracing out the time-evolved degrees of freedom, we analyze the entanglement formation using the concurrence measure. We show that the concurrence depends on the virtual photon exchanged and the positions of the layer through the interlayer photon propagator. Furthermore, we find that the formation of entanglement between equal energy electrons tends to be enhanced when they move in perpendicular directions. Our results indicate that a buckled honeycomb structure and a large spin-orbit interaction favor the entanglement harvesting.

Microstructure-Reconfigured Graphene Oxide Aerogel Metamaterials for Ultrarobust Directional Sensing at Human-Machine Interfaces.

Graphene aerogels hold huge promise for the development of high-performance pressure sensors for future human-machine interfaces due to their ordered microstructure and conductive network. However, their application is hindered by the limited strain sensing range caused by the intrinsic stiffness of the porous microstructure. Herein, an anisotropic cross-linked chitosan and reduced graphene oxide (CCS-rGO) aerogel metamaterial is realized by reconfiguring the microstructure from a honeycomb to a buckling structure at the dedicated cross-section plane. The reconfigured CCS-rGO aerogel shows directional hyperelasticity with extraordinary durability (no obvious structural damage after 20 000 cycles at a directional compressive strain of ≤0.7). The CCS-rGO aerogel pressure sensor exhibits an ultrahigh sensitivity of 121.45 kPa-1, an unprecedented sensing range, and robust mechanical and electrical performance. The aerogel sensors are demonstrated to monitor human motions, control robotic hands, and even integrate into a flexible keyboard to play music, which opens a wide application potential in future human-machine interfaces.

Non‐Monotonic Variation of the Low Lattice Thermal Conductivity with Temperature in Penta‐HgO2 Sheet

AbstractInspired by the experimental synthesis of bulk HgO2 with the potential of exfoliation to form a penta‐HgO2 sheet composed entirely of pentagonal motifs, a detailed theoretical study on the lattice thermal conductivity by using first‐principles calculations combined with the unified theory of thermal transport is performed. It is found that the penta‐HgO2 sheet is semiconducting with an indirect bandgap of 1.18 eV and possesses a low lattice thermal conductivity of 2.07 W m−1 K−1 (3.28 W m−1 K−1) along the x (y)‐direction at 300 K. More interestingly, the variation of its thermal conductivity with temperature is non‐monotonic, different from most cases. The phonon dispersion, phonon scattering, and phonon coherence is further systematically investigated to understand the underlying physics. This results suggest that the strong intrinsic anharmonicity resulting from its unique atomic configuration with the buckled structure and the heavy element of Hg leads to a high scattering rate, resulting in the ultralow particle‐like thermal transport of 0.20 W m−1 K−1 (0.01 W m−1 K−1) in the x (y)‐direction, while the narrow average frequency interval and strong phonon linewidth are responsible for the dominant coherent thermal transport and non‐monotonic variation of the low lattice thermal conductivity of the penta‐HgO2 sheet.

Influence of elasto-plastic behavior of thin films on circular buckling structures

We report on circular buckles experimentally observed by optical and atomic force microscopy on gold ductile thin films deposited by physical vapor deposition on silicon wafers. It is shown that, whatever the radius blister dimensions, their maximum deflections are higher than those expected by the elastic theory. It suggests that plastic events may take place in the film, impacting on the blister morphology as a result. Based on nanoindentation experiments carried out on our gold films, a proper plastic hardening law has been determined by calculations using the finite elements method. The influence of this elasto-plastic behavior on the buckled circular profiles has been then numerically studied, compared to the experimental observations and discussed.

Coexistence of Defect Morphologies in Three-Dimensional Active Nematics.

We establish how active stress globally affects the morphology of disclination lines of a three-dimensional active nematic liquid crystal under chaotic flow. Thanks to a defect detection algorithm based on the local nematic orientation, we show that activity selects a crossover length scale in between the size of small defect loops and that of long and tangled defect lines of fractal dimension 2. This length scale crossover is consistent with the scaling of the average separation between defects as a function of activity. Moreover, on the basis of numerical simulation in a 3D periodic geometry, we show the presence of a network of regular defect loops, contractible onto the 3-torus, always coexisting with wrapping defect lines. While the length of regular defects scales linearly with the emerging active length scale, it verifies an inverse quadratic dependence for wrapping defects. The shorter the active length scale, the more the defect lines wrap around the periodic boundaries, resulting in extremely long and buckled structures.

Structural dynamics around a hydrogen bond: Investigating the effect of hydrogen bond strengths on the excited state dynamics of carboxylic acid dimers.

The photochemical dynamics of the acetic acid and trifluoro-acetic acid dimers in hexane are studied using time-resolved infrared absorption spectroscopy and abinitio electronic structure calculations. The different hydrogen bond strengths of the two systems lead to changes in the character of the accessed excited states and in the timescales of the initial structural rearrangement that define the early time dynamics following UV excitation. The much stronger hydrogen bonding in the acetic acid dimer stabilizes the system against dissociation. Ground state recovery is mediated by a structural buckling around the hydrogen bond itself with no evidence for excited state proton transfer processes that are usually considered to drive ultrafast relaxation processes in hydrogen bonded systems. The buckling of the ring leads to relaxation through two conical intersections and the eventual reformation of the electronic and vibrational ground states on a few picosecond timescale. In trifluoro-acetic acid, the weaker hydrogen bonding interaction means that the dimer dissociates under similar irradiation conditions. The surrounding solvent cage restricts the full separation of the monomer components, meaning that the dimer is reformed and returns to the ground state structure via a similar buckled structure but over a much longer, ∼100ps, timescale.

Post-Buckling Analysis of E-Glass Fiber Reinforced Thin-Walled Cylindrical Composite

Post buckling analysis of E-glass fiber reinforced cylindrical composite under axial compression using both experimental and numerical method is presented. Using the Eigen value buckling analysis, the studies employ a mixture ratio of E-glass fiber composite of chopped strand mat. Five molds of each E-glass fiber mixture were reinforced with polyester resin to produce cylindrical shells of equal dimensions. Various cylindrical specimens’ predicted critical buckling load were tested and recorded using a compressive loading machine. Comparisons were made to ascertain the cylindrical shells buckling and post buckling behavior at certain load levels between the experimental and analytical results. A one-way Anova was used to compare the outcome of the theoretical, experimental and numerical methods of analysis and the result showed that there is no evidence to suggest difference between the three methods applied in the buckling load analysis. The post buckled shapes of the samples were obtained and recorded as bulge diamond shape of a buckled cylindrical structure. The effective mechanical properties of the chopped strand mat (CSM) reinforced composite cylinder were recorded from the experiment which has modulus of Elasticity 197.707 N/mm2, Poisson’s ratio of 0.22 and density of 1250 Kg/m3.

A High‐Stretchability, Wide Detection Range, and Wide Temperature Range Ti3C2Tx MXene/Graphene Strain Sensor Based on a Buckling Structure

AbstractFlexible wearable sensors have the characteristics of flexibility, comfort, and wearability, and have shown great potential in future electronic products. Despite significant efforts in developing stretchable electronic materials and structures, the development of flexible strain sensors with a wide temperature range, high sensitivity, broad detection range, and good interface stability remains challenging. Here, strain sensors with buckled structures are fabricated using high and low‐temperature resistant material Ti3C2Tx MXene/graphene, PDMS 184. The conductive material Ti3C2Tx MXene/graphene exhibits excellent interface interaction with PDMS 184, addressing not only the poor compatibility issue between the conductive material and the flexible substrate, but also demonstrating good stability and cycling performance. Buckled structure improves the stretchability and linearity of strain sensors. The fabricated strain sensor is suitable for a wide temperature range (−40 to 120 °C) and exhibits high stretchability (120% strain). The strain sensor demonstrates rapid response times at different temperatures: −40 (72.6 ms), 0 (62.7 ms), and 120 °C (52.7 ms). The strain sensor exhibits high sensitivity at different temperatures: −40 (GF = 0.38), 0 (GF = 0.24), 40 (GF = 0.66), and 120 °C (GF = 1.47). The strain sensor has a wide detection range (0.1% to 120%) and excellent cycling stability. In addition, Ti3C2Tx MXene/graphene strain sensors can accurately capture various human activities, such as blinking, speaking, finger bending, and wrist bending.

Realization of large-area ultraflat chiral blue phosphorene

Blue phosphorene (BlueP), a theoretically proposed phosphorous allotrope with buckled honeycomb lattice, has attracted considerable interest due to its intriguing properties. Introducing chirality into BlueP can further enrich its physical and chemical properties, expanding its potential for applications. However, the synthesis of chiral BlueP remains elusive. Here, we demonstrate the growth of large-area BlueP films on Cu(111), with lateral size limited by the wafer dimensions. Importantly, we discovered that the BlueP is characterized by an ultraflat honeycomb lattice, rather than the prevailing buckled structure, and develops highly ordered spatial chirality plausibly resulting from the rotational stacking with the substrate and interface strain release, as further confirmed by the geometric phase analysis. Moreover, spectroscopic measurements reveal its intrinsic metallic nature and different characteristic quantum oscillations in the image-potential states, which can be exploited for a range of potential applications including polarization optics, spintronics, and chiral catalysis.

Silicene growth mechanisms on Au(111) and Au(110) substrates

Despite the remarkable theoretical applications of silicene, its synthesis remains a complex task, with epitaxial growth being one of the main routes involving depositing evaporated Si atoms onto a suitable substrate. Additionally, the requirement for a substrate to maintain the silicene stability poses several difficulties in accurately determining the growth mechanisms and the resulting structures, leading to conflicting results in the literature. In this study, large-scale molecular dynamics simulations are performed to uncover the growth mechanisms and characteristics of epitaxially grown silicene sheets on Au(111) and Au(110) substrates, considering different temperatures and Si deposition rates. The growth process has been found to initiate with the nucleation of several independent islands homogeneously distributed on the substrate surface, which gradually merge to form a complete silicene sheet. The results consistently demonstrate the presence of a buckled silicene structure, although this characteristic is notably reduced when using an Au(111) substrate. Furthermore, the analysis also focuses on the quality and growth mode of the silicene sheets, considering the influence of temperature and deposition rate. The findings reveal a prevalence of the Frank–van der Merwe growth mode, along with diverse forms of defects throughout the sheets.

Forced resonance of a buckled beam flexibly restrained at the inner point

Restraints along slender structures, such as pipes conveying fluid and beams, play important roles in enhancing their bending stiffness. The current work investigates the influence of the midpoint restraint on the buckled axial force and dynamic characteristics for the first time. A continuous model is introduced by treating the midpoint restraint force as a concentrated force using Dirac function. The influence of the midpoint restraint is discussed based on modal expansion, and a partitioned model is proposed for validation. The conclusion is that the continuous model has good accuracy. Based on this model, it finds out two stable buckled states changing with the midpoint stiffness. The first stable buckled state occurs under weak midpoint restraint and has a cambered shape. The zero- and double frequency components occur in symmetric modal shapes and the response is softened along the whole beam. However, in the second stable buckled state, it turns into a whole sine function shape. The zero- and double frequency components just occur in the second modal shape, and the soften phenomenon doesn’t occur at the midpoint. With increasing excitation amplitude, a bubble appears on the primary resonance peak while another resonance peak emerges nearby it. This work explains the influence of midpoint stiffness on nonlinear resonance and enhances the study of the nonlinear behavior of buckled slender structures.

Full-landscape selection rules of electrons and phonons and temperature-induced effects in 2D silicon and germanium allotropes

The electron-phonon (el-ph) and phonon-phonon interactions play crucial roles in determining the electronic and thermal transport properties of materials. Using the group theory and ab-initio calculations, we have derived the full-landscape selection rules for intravalley and intervalley scattering for carriers in 2D silicon and germanium allotropes with low buckled (LB) and large honeycomb dumbbell (LHD) structures, showing dominant role of optical modes in total el-ph coupling in LHD Si/Ge due to most el-ph scattering channels via acoustic modes blocked by symmetries. Remarkably, we show that due to the relatively large optical phonon bandwidth and “bunching effect" of acoustic phonon bands, the selection rules of three-phonon interactions reveal the dominant ooo and aoo channels in LHD and LB Si/Ge, respectively, and the temprature-induced effects significantly increase the ratio between mode-resolved four-phonon interactions and three-phonon interactions in most of the phonon-frequency region, finally leading to the low thermal conductivities in both LB and LHD Si/Ge. Furthermore, we observe the anomalous temperature-dependent thermal conductivities in LHD Ge, resulted from the vanishing quasi-acoustic-optical phonon gap under the temperature-induced effects. By considering full el-ph coupling and higher-order anharmonic phonon-phonon interactions, the maximal thermoelectric figures of merits in LHD Si and LB Ge are found to reach 1.06 and 0.66 at 700 K, respectively, significantly surpassing their bulk counterparts. Our work is poised to stimulate wide-ranging exploration into phonon transport across diverse materials, and benefits both fundamental knowledge and advanced technologies of 2D Si/Ge allotropes.

Electronic and magnetic properties of GeS monolayer effected by point defects and doping.

In this work, defect engineering and doping are proposed to effectively functionalize a germanium sulfide (GeS) mononolayer. With a buckled hexagonal structure, the good dynamical and thermal stability of the GeS monolayer is confirmed. PBE(HSE06)-based calculations assert the indirect gap semiconductor nature of this two-dimensional (2D) material with a relatively large band gap of 2.48(3.28) eV. The creation of a single Ge vacancy magnetizes the monolayer with a total magnetic moment of 1.99 μB, creating a the feature-rich half-metallic nature. VaS vacancy, VaGeS divacancy, SGe and GeS antisites preserve the non-magnetic nature; however, they induce considerable band gap reduction of the order 47.98%, 89.11%, 29.84%, and 62.5%, respectively. By doping with transition metals (TMs), large total magnetic moments of 3.00, 4.00, and 5.00 μB are obtained with V, Cr-Fe, and Mn impurities, respectively. The 3d orbital of TM dopants mainly regulates the electronic and magnetic properties, which induces either the half-metallic or diluted magnetic semiconductor nature. It is found that the doping site plays a determinant role in the case of doping with VA-group atoms (P and As). The GeS monolayer can be metallized by doping the Ge sublattice, meanwhile both spin states exhibit semiconductor character with strong spin polarization upon doping the S sublattice to obtain a diluted magnetic semiconductor nature with a total magnetic moment of 1.00 μB. In these cases, the magnetism originates mainly from P and As impurities. The obtained results suggest an efficient approach to functionalize the GeS monolayer for optoelectronic and spintronic applications.

Kirigami-Triggered Spoof Plasmonic Interconnects for Radiofrequency Elastronics.

The flexible and conformal interconnects for electronic systems as a potential signal transmission device have great prospects in body-worn or wearable applications. High-efficiency wave propagation and conformal structure deformation around human body at radio communication are still confronted with huge challenges due to the lack of methods to control the wave propagation and achieve the deformable structure simultaneously. Here, inspired by the kirigami technology, a new paradigm to construct spoof plasmonic interconnects (SPIs) that support radiofrequency (RF) surface plasmonic transmission is proposed, together with high elasticity, strong robustness, and multifunction performance. Leveraging the strong field-confinement characteristic of spoof surface plasmons polaritons, the Type-I SPI opens its high-efficiency transmission band after stretching from a simply connected metallic surface. Meanwhile, the broadband transmission of the kirigami-based SPI exhibits strong robustness and excellent stability undergoing complex deformations, i.e., bending, twisting, and stretching. In addition, the prepared Type-II SPI consisting of 2 different subunit cells can achieve band-stop transmission characteristics, with its center frequency dynamically tunable by stretching the buckled structure. Experimental measurements verify the on-off switching performance in kirigami interconnects triggered by stretching. Overcoming the mechanical limitation of rigid structure with kirigami technology, the designer SPIs exhibit high stretchability through out-of-plane structure deformation. Such kirigami-based interconnects can improve the elastic functionality of wearable RF electronics and offer high compatibility to large body motion in future body network systems.

Many Body Aspects on the Lattice Vibrational Properties of Germanene and Silicene along Highly Symmetry Directions

The investigation of lattice vibrational properties in monolayer two-dimensional honeycomb lattices comprising 2D group-IV semiconductor materials such as Germanene and Silicene (Low Buckled structure) holds immense significance in the realm of research, owing to their potential integration into the forthcoming electronic sector for information technology. The ductile nature of 2D group-IV semiconductor materials enables seamless integration with existing semiconductor technology on substrates, setting them apart from Graphene. Our primary objective revolves around comprehending the lattice vibrational properties of Germanene and Silicene (LB) through the examination of their honeycomb and buckled lattice structures. We use the Adiabatic Bond Charge Model with a Python program to derive vibrational frequencies at the Г points along highly symmetrical directions. Moreover, we extensively analyze the acoustical and optical contributions to the lattice vibrational frequencies. We anticipate that the phonon frequencies along the Г‒M direction for 2D atomically thin Germanene and Silicene will yield reasonably similar outcomes to those other research groups achieve.

Recent Advances in Phosphorene: Structure, Synthesis, and Properties.

Phosphorene is a 2D phosphorus atomic layer arranged in a honeycomb lattice like graphene but with a buckled structure. Since its exfoliation from black phosphorus in 2014, phosphorenehas attracted tremendous research interest both in terms of synthesis and fundamental research, as well as in potential applications. Recently, significant attention in phosphorene is motivated not only by research on its fundamental physical properties as a novel 2D semiconductor material, such as tunable bandgap, strong in-plane anisotropy, and high carrier mobility, but also by the study of its wide range of potential applications, such as electronic, optoelectronic, and spintronic devices, energy conversion and storage devices. However, a lot of avenues remain to be explored including the fundamental properties of phosphorene and its device applications. This review recalls the current state of the art of phosphorene and its derivatives, touching upon topics on structure, synthesis, characterization, properties, stability, and applications. The current needs and future opportunities for phosphorene are also discussed.

Study on Hierarchically Buckled Surface Regulation for Stretchable Porous Microarchitectures Fibers

Breath figure technology’s potential for surface modification of fibers to enable new functions in wearables is attractive. However, the development of extensible, multifunctional elastic fibers with hierarchically porous architectures remains a difficulty. We study a new technique for fiber surface modification based on the modified breath figure technique, which includes material selection, interfacial self-assembly, and pre-stretch ratio. The fabricated hierarchically porous elastic fibers exhibit features like finger joint buckled skin and a unique stretchable buckled porous structure. Influential factors such as elastic fiber base diameter, brick polymer solution concentration, and pre-stretch ratio were studied. This study presents a novel design and preparation of functional fiber materials with porous microstructures.

Point Defects in Buckled Honeycomb PAs Monolayer: A Systematic Study of Stability, Electronic, and Magnetic Properties

AbstractIn this work, the effects of point defects on the electronic and magnetic properties of PAs monolayer are investigated. PAs monolayer is stable in a buckled hexagonal structure, exhibiting indirect gap semiconductor character and is metallized under the presence of vacancies due to the dangling bonds around defect sites. Meanwhile, the non‐magnetic semiconductor character is preserved upon creating antisite defects with a negligible variation of the band gap. Significant magnetism as well as feature‐rich electronic properties are induced by p‐ and n‐type defects. Specifically, doping with Si and Ge atoms leads to the emergence of the magnetic semiconductor nature. In these cases, the total magnetic moment of 1 is obtained, where dopant atoms are mainly responsible for the magnetization. Besides, doping with Br induce the half‐metallic nature with a total magnetic moment of 2 , where magnetic properties are produced by the dopant and its neighbor due to the strong hybridization. In contrast, weak hybridization is the main reason for the absence of magnetism in the Cl‐doped PAs monolayer. Results presented herein introduce the creation of point defects in buckled semiconductor PAs monolayer as efficient functionalization approaches for optoelectronic and spintronic applications.

Research progress on stretchable organic light-emitting devices based on buckled structures

Research progress on stretchable organic light-emitting devices based on buckled structures

Structural reorganization of ultrathin g-C3N4 nanosheets for significantly boosting wide-spectrum-driven CO2 photoreduction

Graphitic carbon nitride (g-C3N4) exhibits moderate CO2 photoreduction due to fast recombination of photoexcited charges and low-grade visible light absorption. Herein, we synthesized highly polymerized ultrathin g-C3N4 nanosheets by structural reorganization. Both experimental and theoretical calculations indicate that amino groups stabilized by hydrogen bonding networks are the easiest to remove to form a more stable bridged N-(C)3. This procedure provides additional electron transfer channels with an extended conjugated π → π* system and buckled plane structure with activated n → π* electronic transitions. This new configuration significantly improves the separation efficiency of photoexcited charges and widens the light absorption range. As a result, the prepared g-C3N4 shows efficient CO2-to-CO conversion with a CO production rate of 12.95 μmol g-1 h−1 under λ ≥ 420 visible light and 2 μmol g-1 h−1 under λ ≥ 500 visible light, respectively. This work offers a new design idea for highly active visible-light-driven g-C3N4 for CO2 photoreduction.