Out-of Plane Research Articles

Behaviour of unreinforced masonry walls retrofitted by using basalt textile reinforced mortar

Basalt textile reinforced mortar (BTRM) has drawn attention as an innovative retrofitting composite, due to its superior characteristics including simplicity in application, high performance in addition to low cost, in comparison to FRP. Unreinforced masonry (URM) buildings constitute a large portion of current worldwide buildings which suffer lack of resistance to wind and seismic loading. Thus, BTRM represents an ideal technique for out of plane retrofitting for URM walls. This study aims to investigate the out of plane behavior of URM walls retrofitted by using BTRM. A Group of five URM wall specimens were constructed in vertical spanning scheme. Another group of five specimens were constructed in horizontal spanning scheme. Parameters under study for both groups include mesh opening size (5 × 5 mm and 10 × 10 mm), number of reinforcing layers (two and four layers) and retrofitting scheme (one side or both sides). The efficiency of BTRM has been demonstrated through the investigation results. Out of plane flexural capacity remarkably increased by 188% to 400% comparatively to control samples. In addition, energy absorption increased 22 to 66 times. An ACI model has been modified to be more reliable for flexural capacity prediction retrofitted URM walls.

Multianion induced out-of-plane proper polarization in oxyfluoride Aurivillius Bi2TiO4F2

We explore the effect of anion ordering on the ferroelectric properties of the oxyfluoride Aurivillius Bi2TiO4F2 from first-principles calculations. We first identify the phonon instabilities in the high symmetry reference phases and build the energy diagram for the different low symmetry metastable phases coming from these instabilities. We found that the apical ordering of fluorine is more stable than the equatorial one but mixing apical and equatorial ordering together is even more favorable. For each fluorine ordering, the ground state is polar and exhibits a proper in-plane polarization. We also found that the apical ordering can exhibit a proper out-of plane polarization as large as 35 μc/cm2, which is unexpected in layered crystals. This finding opens the possibility to design polarization perpendicular to the stacking layers in ferroelectrics layered perovskites through multianion engineering, a property strongly desired for technological applications like FeRAM devices.

Electronic states driven by the crystal field in two-dimensional materials: The case of antimonene

The search for novel two-dimensional (2D) giant Rashba semiconductors is a crucial step in the development of spintronic technology. The electronic properties and growth mode of antimonene grown by molecular beam epitaxy were investigated using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy. Results reveal the semiconducting nature of antimonene and the presence of a highly mobile 2D hole gas (2DHG) near the Fermi level. The anisotropy factor and Fermi velocity of the 2DHG are sensitively dependent on the crystal structure and in-plane lattice parameters of antimonene. Antimonene with small lattice parameters exhibits a small anisotropy factor and electron effective mass. Furthermore, the perpendicular (out of plane) electric field breaks the inversion symmetry and, when combined with strong spin-orbit coupling, induces the spin splitting of the valence band of antimonene. ARPES and work function measurements shed light on the band alignment between antimonene and the substrates and confirmed the presence of a nonignorable interface dipole of approximately 0.2 eV. This dipole could be the cause of approximately 80 meV spin splitting at the valence-band maximum of antimonene, a value that is significantly greater than the thermal energy at room temperature. In addition, the spin-splitting degree depends on the interface dipole strength. The gate voltage can generate the out of plane electric field and regulate the spin state similar to an internal electric field. Our results suggest that antimonene and its van der Waals heterostructure system grown on substrates could be used to develop highly efficient spin field-effect transistors and nanospintronic devices.

Residual stress tuned magnetic properties of thick CoMnP/Cu multilayers

Electrodeposited hard magnetic thick films have vast applications in the microelectromechanical systems (MEMS). Yet the very large residual stresses (σr) built-up in monolayered thick magnetic films leads to cracks, dimensional changes and deteriorated magnetic properties. Here, we explored quantitatively magnetic properties of CoMnP/Cu multilayers tuned by σr, which in turn are varied by the inserted soft Cu interlayer and thickness of single CoMnP magnetic layers. The configuration of the multilayers is an alternating CoMnP/Cu on Cu-substrate. The thickness of Cu interlayer was 1.4 μm. We kept a sum of all magnetic layers in the multilayers at ∼20 μm to benchmark with a 19.4 μm monolayered CoMnP. The magnetic layers are 94 wt.% Co and possess highly textured (002) hexagonal close packed microstructures. We characterized the apparent crystallite stresses through sin2ψ method by X-ray diffractometer (XRD) and residual film stress by curvature method. The insertion of Cu interlayers effectively reduces σr by 23% through stacking with six single-layered CoMnP. The out-of-plane (OP) anisotropy is slightly reduced. While the maximum energy product in the in-plane (IP) direction can be significantly enhanced by 430% ∼ 690% with increasing the number of the CoMnP single layer in the multilayers. The magneto-elastic behaviors well explain the evolution of the total anisotropy energy of the mono- and multi-layers. By CoMnP/Cu configurations we successfully worked out a strategy to preserve prestigious OP performance while to enhance IP properties by 4 to 6 times to meet ever increasing challenges in MEMS applications.

Linearly shifting ferromagnetic resonance response of La0.7Sr0.3MnO3 thin film for body temperature sensors.

Human body temperature not only reflects vital signs, but also affects the state of various organs through blood circulation, and even affects lifespan. Here a wireless body temperature detection scheme was presented that the temperature was extracted by investigating the out-of-plane (OP) ferromagnetic resonance (FMR) field of 10.2 nm thick La0.7Sr0.3MnO3 (LSMO) film using electron paramagnetic resonance (EPR) technique. Within the range of 34–42 °C, the OP FMR field changes linearly with the increasing or decreasing temperature, and this variation comes from the linear responses of magnetization to the fluctuant temperature. Using this method, a tiny temperature change (< 0.1 °C) of organisms can be detected accurately and sensitively, which shows great potential in body temperature monitoring for humans and mammals.

Tuning valley splitting and magnetic anisotropy of multiferroic CuMP2X6 (M=Cr,V;X=S,Se) monolayer

Monolayer $\mathrm{Cu}M{\mathrm{P}}_{2}{X}_{6}$ $(M=\mathrm{Cr},\mathrm{V};X=\mathrm{S},\mathrm{Se})$ has been attracting increasing attention due to the ferromagnetism derived from the indirect exchange interaction between Cr (V) atoms and the ferroelectricity originating from the spontaneous displacement of Cu atoms. Using first-principles calculations, we predicted the intrinsic valley splittings and anomalous valley Hall effect in $\mathrm{Cu}M{\mathrm{P}}_{2}{X}_{6}$ monolayers. In addition, the valley splittings and Berry curvature are independent of the orientation of out of plane (OOP) ferroelectric polarization, which makes it a promising storage device with dual degrees of freedom in ferroelectric polarization and ferrovalleys. Due to the variations in the energy of the spin-dependent valence-band maximum (VBM) and orbital compositions of the valleys, the magnitude of valley splitting at VBM can be effectively tuned by the biaxial strain and external electric field. Large OOP magnetic anisotropy can be obtained by changing the energy and occupation (unoccupation) states of $d$ orbital compositions through strain and charge doping, respectively, and the magnetic anisotropy of $\mathrm{Cu}M{\mathrm{P}}_{2}{X}_{6}$ increases with increasing tensile biaxial strain from \ensuremath{-}5% to 5%. Our research results are expected to tune the valley splittings and magnetic anisotropy of $\mathrm{Cu}M{\mathrm{P}}_{2}{X}_{6}$ and to help understand the physical mechanism.

Wrinkling and multiplicity in the dynamics of deformable sheets in uniaxial extensional flow

The processing of thin-structured materials in a fluidic environment, from nearly inextensible but flexible graphene sheets to highly extensible polymer films, arises in many applications. So far, little is known about the dynamics of such thin sheets freely suspended in fluid. In this work, we study the dynamics of freely suspended soft sheets in uniaxial extensional flow. Elastic sheets are modeled with a continuum model that accounts for in-plane deformation and out-of-plane bending, and the fluid motion is computed using the method of regularized Stokeslets. We explore two types of sheets: "stiff" sheets that strongly resist bending deformations and always stay flat, and "flexible" sheets with both in-plane and out-of plane deformability that can wrinkle. For stiff sheets, we observe a coil-stretch-like transition, similar to what has been observed for long-chain linear polymers under extension as well as elastic sheets under planar extension: in a certain range of capillary number (flow strength relative to in-plane deformability), the sheets exhibit either a compact or a highly stretched conformation, depending on deformation history. For flexible sheets, sheets with sufficiently small bending stiffness wrinkle to form various conformations. Here, the compact-stretched bistability still occurs, but is strongly modified by the wrinkling instability: a highly-stretched planar state can become unstable and wrinkle, after which it may dramatically shrink in length due to hydrodynamic screening associated with wrinkling. Therefore, wrinkling renders a shift in the bistability regime. In addition, we can predict and understand the nonlinear long-term dynamics for some parameter regimes with linear stability analysis of the flat steady states.

Lithofacies, mineralogy, and pore types in Paleozoic gas shales from Western Peninsular Malaysia

An experimental study including Fourier Transform Infrared (FTIR), thin section petrography, scanning electron microscope (SEM) imaging, and low-pressure nitrogen adsorption analysis has been conducted to assess the mineralogy, lithofacies, pore types, and pore properties of the potential Paleozoic gas shales from Western Peninsula (WP) Malaysia. In WP Malaysia, shale samples from seven Paleozoic Formations were investigated and classified into four age categories. FTIR analysis documented the presence of aromatic out of plane and in plane bending, aliphatic CH bending, OH functional group, and presence of quartz, carbonates, kaolinite, and illite minerals. Four lithofacies identified from the petrographic analysis of the Paleozoic shale include silica-rich argillaceous mudstone (SAM), clay-rich siliceous mudstone (CSM), silica dominated lithofacies mudstone (SD), and mixed carbonate mudstone (MCM). In comparison, the mineral content and lithofacies found in Paleozoic shales are close to the Niutitang, Longmaxi, Marcellus, and Eagle Ford shales. Furthermore, with high organic matter content, laminated fabric, and with more brittle mineralogy, SD lithofacies would be a highly promising type of lithofacies in WP Malaysia. FESEM studies show that organic matter pores, interparticle pores, and intraparticle pores are the main pore types. Pore sizes analyze through N2 adsorption reveal radii of lesser than 25 nm contribute mainly to porosity and total pore volume. Micropore volume of the WP Malaysia shale was found to be greatly similar to hot shales from USA and China, while surface area values of only older Paleozoic shales, i.e., S-D and Devonian, are close to USA shales.

Failure modes of reinforced concrete walls under cyclic loading: Experimental study and prediction method

Failure mode identification and prediction of RC walls are of critical importance for seismic strengthening of existing members and target quantification of performance-based seismic design. This paper aims to better understand the failure modes of RC walls under cyclic loading. Firstly, cyclic test was conducted to examine the effect of reinforcement strength (fy = 476 MPa vs 641 MPa), axial load ratio (0.1 vs 0.2), and shear demand to capacity ratio (Vf/vs = 0.38 vs 1.25) on the failure modes of RC walls. Then, the existing experimental data of 168 wall specimens was collected, and the statistical analyses were carried out to obtain the critical parameters for different failure modes, which were used to establish the prediction method for failure modes. Finally, the accuracy of the prediction method was evaluated by the experimental data. The study results show that the larger axial load can both increase the likelihood of concrete crushing as well as various out of plane buckling modes; shear demand to capacity ratio is a critical parameter to affect the failure process and mode of RC walls. The statistical analyses show that when shear span ratio (λ) ≥ 2.7 and Vf/vs ≤ 0.60, the wall specimens fail in flexure; when Vf/vs ≥ 1, or λ ≤ 1.1 and Vf/vs ≥ 0.80, the wall specimens fail in shear, and the wall specimens not within the above ranges fail in flexure-shear mode. The evaluation results show that the prediction method has a reasonable accuracy.

Stability of two-dimensional complex plasma monolayers in asymmetric capacitively coupled radio-frequency discharges.

In this article, the stability of a complex plasma monolayer levitating in the sheath of the powered electrode of an asymmetric capacitively coupled radio-frequency argon discharge is studied. Compared to earlier studies, a better integration of the experimental results and theory is achieved by operating with actual experimental control parameters such as the gas pressure and the discharge power. It is shown that for a given microparticle monolayer at a fixed discharge power there exist two threshold pressures: (i) above a specific pressure p_{cryst}, the monolayer always crystallizes; (ii) below a specific pressure p_{MCI}, the crystalline monolayer undergoes the mode-coupling instability and the two-dimensional complex plasma crystal melts. In between p_{MCI} and p_{cryst}, the microparticle monolayer can be either in the fluid phase or the crystal phase: when increasing the pressure from below p_{MCI}, the monolayer remains in the fluid phase until it reaches p_{cryst} at which it recrystallizes; when decreasing the pressure from above p_{cryst}, the monolayer remains in the crystalline phase until it reaches p_{MCI} at which the mode-coupling instability is triggered and the crystal melts. A simple self-consistent sheath model is used to calculate the rf sheath profile, the microparticle charges, and the microparticle resonance frequency as a function of power and background argon pressure. Combined with calculation of the lattice modes the main trends of p_{MCI} as a function of power and background argon pressure are recovered. The threshold of the mode-coupling instability in the crystalline phase is dominated by the crossing of the longitudinal in-plane lattice mode and the out-of plane lattice mode induced by the change of the sheath profile. Ion wakes are shown to have a significant effect too.

Parametric study on longitudinal and out-of-plane compressive properties, progressive damage and failure of 3D five-directional braided composites

The parametric finite element model (FEM) of three-dimensional five-directional (3D5d) braided composites was established by considering the yarn cross-section and the spatial contact between the yarns. The longitudinal and out-of-plane compressive mechanical properties and progressive damage of composites with various parameters were predicted and experimentally verified. As the fiber volume fraction increase, the mechanical performance improve, both in longitudinal and out-of plane direction. With the increase of braiding angle, the longitudinal mechanical properties decrease and the out-of-plane strength decreases while the modulus increases. The stress–strain curves show brittleness and toughness in longitudinal and out-of-plane, respectively. Due to the influence of stress transfer and component contact, damage is more likely to occur at the connection parts of each component.

Airbag loading test and numerical simulation on out-of-plane mechanical behavior of a cast-in-situ composite wall with MTPC

Although infilled walls are designed to serve as nonstructural components in frame buildings, their out-of-plane (OP) collapse during earthquake events may trigger additional damage to other structural components and inflict heavy casualties. Taking advantages of the metal tailing porous concrete (MTPC) and light-gauge steel studs, a new cast-in-situ composite wall with MTPC (CCWM) can be developed and regarded as a potential substitute for traditional masonry infilled walls. This paper experimentally investigates the OP mechanical behavior of a full-scaled CCWM via airbag loading test. A CCWM specimen with dimension of 2.4 m × 1.2 m × 0.2 m is fabricated by pouring MTPC into the cavity formed by panels and light-gauge steel stud system. The specimen is placed vertically in an elaborate loading system composed of steel frame, reaction brace, horizontal beams and a polyethylene airbag. Under the uniform OP force provided by the slowly inflated airbag, the failure pattern, load-displacement curves and strains of light gauge steel studs of the CCWM are observed and recorded during the test. Moreover, the finite element model of the specimen is developed in ABAQUS platform and the effects of slenderness ratio and aspect ratio on the OP mechanical behavior of the CCWM are numerically investigated. The results indicate that the specimen cracked vertically along the central line of the upper half part of the wall, and the connections between the support plates and vertical lattice studs are vulnerable locations for the CCWM. Owing to the special constitution of the CCWM, the arching action is short-term, and the crack strength can be adopted as the OP bearing capacity of the CCWM since it is quite close to the ultimate strength. Moreover, numerical results reveal that the OP strength and stiffness of the CCWM decrease when the slenderness ratio increases, but enhance with increasing aspect ratio.

Probing Magnetic Anisotropy in Kagome Antiferromagnetic Mn$_3$Ge with Torque Magnetometry

We investigate the magnetic symmetry of the topological antiferromagnetic material Mn$_3$Ge by using torque measurements. Below the Neel temperature, detailed angle-dependent torque measurements were performed on Mn$_3$Ge single crystals in directions parallel and perpendicular to the Kagome basal plane. The out-of plane torque data exhibit $\pm\sin\theta$ and $\sin2\theta$ behaviors, of which the former results from the spontaneous ferromagnetism within the basal plane and the latter from the in- and out-of-plane susceptibility anisotropy. The reversible component of the in-plane torque exhibits $\sin6\varphi$ behavior, revealing the six-fold symmetry of the in-plane magnetic free energy. Moreover, we find that the free energy minima are pinned to the direction of spontaneous ferromagnetism, which correspond to the maxima of the irreversible component of the in-plane torque. We provide an effective spin model to describe the in-plane magnetic anisotropy. Our results demonstrate that the ground state of Mn$_3$Ge is described by the coexistence of a strong six-fold antichiral order and a weak ferromagnetic order induced by second-order spin anisotropy.

Temporal-spatial mode competition in slug-flow induced vibration of catenary flexible riser in both in plane and out of plane

The slug-flow induced vibration (SIV) of a catenary flexible riser with an aspect ratio of 360 is experimentally investigated in this work. Four different flow rates for the internal gas-liquid slug flow are considered in the tests that carried out at a fixed gas-liquid ratio of 3.0 in a small-scale air-water test loop. The temporal-spatial mode competition is discussed in terms of the response amplitudes, frequencies, modal weights, transferred energy between the riser and flow, pressure fluctuations and slug flow characteristics. Experimental results indicate that the modal weights of higher modes increase with the flow rate although the in-plane response is dominated by the fundamental mode, resulting in the intense mode competition. The occurrence of mode transition first emerges at the response trough, presenting the higher second modal weight. The distinct switching between the first and second mode is observed for the pipe section between the response peak and trough, and such mode switching becomes more pronounced as the flow rate grows. The distribution and lengths of liquid slugs passing through the riser affect the mode switching in terms of the distribution and magnitude of fluid forces. The riser storages the energy extracted from the fluid when it approaches to the equilibrium position, while releases the energy as it departs the equilibrium position. The occurrence of out-of-plane response is found when the mixture velocity exceeds 2.0 m/s. The out-of-plane frequencies appear in the in-plane response, and vice versa, manifesting the interaction between the in-plane and out-of-plane responses.

Tunable spin-valley splitting and magnetic anisotropy of two-dimensional 2H-VS2/h-VN heterostructure

Valleytronics is proposed to explore a new approach for information storage using valley degrees of freedom. In this work, the electronic structure, spin-valley splitting and magnetic anisotropy (MA) of two-dimensional (2D) 2H-VS2/h-VN magnetic van der Waals (vdW) heterostructure are investigated systematically by first-principles calculations. The results show that the considerable spin splitting of 364.7 meV and 543.7 meV are observed at the K and K' valleys, respectively, generating an intrinsic valley splitting of 68.9 meV in the valence band for the 2H-VS2/h-VN heterostructure, which corresponds to an effective Zeeman magnetic field of 774 T based on the k·p model. The valley splitting of 2H-VS2 is well preserved in the heterostructure and can be further adjusted by altering stacking patterns, in-plane strain and interfacial distance due to the interfacial orbital hybridization. Compared with the pristine 2H-VS2 monolayer, the 2H-VS2 of heterostructure still exhibits the in-plane MA, which mainly originates from the positive contribution of the matrix element difference between the V dxy and dx2-y2 orbitals. With the increase of strain from −2% to 3%, the orientation of easy magnetization axis is transformed from in-plane to out of plane. These results suggest that the 2H-VS2/h-VN heterostructure is a potential candidate in further valleytronics and spintronics.

Strain rate effects on the thermomechanical behavior of glass/polyester composite joints

AbstractFor several decades, composite materials have been used in different applications due to their multiple advantages. It has become necessary to understand the dynamic behavior of these materials under critical loads. In‐plane (IP) and out‐of‐plane (OP) dynamic compression tests were investigated on a cubic specimen of composite joints under low to high strain rates using the Split Hopkinson Pressure Bars (SHPB) technique. The specimens consist of two adherents (glass/polyester composite) assembled by an adhesive with different thicknesses (1 and 2 mm). During the experimental tests, the high‐speed camera was used to check the damage history and the failure mechanisms on adhesively bonded composite joints. The sample surface temperatures were monitored using an infrared camera (IR). For bonding of two composite substrates, it can be noted that the thickness of the adhesive has a significant effect on the dynamic behavior and the kinetics of the damage. It has been concluded that the damage was localized at the level of the layers in the case of in‐plane loading and the level of the adhesive zone in the case of out‐of‐plane loading. The thermomechanical behavior of cubic specimens of adhesively bonded joints subjected to dynamic compression has been studied. The results underline the sensitivity of the dynamic behavior of the adhesively bonded joints to the strain rate, the loading direction and the appearance of heat dissipation linked to the increase in temperature following the initiation of damage. This rise of temperature can dangerously approach the glass transition temperature of the matrix.

Simultaneous measurement of pole figure and residual stress for polycrystalline thin films: ω–φ′ compensated grazing-incidence diffraction in side-inclination mode

A new grazing-incidence diffraction (GID) measurement geometry between in plane and out of plane is proposed. It is improved from the previous ω–φ compensated GID in side-inclination mode for measurement of residual stress in polycrystalline thin films [Wang &amp; van Riessen (2017). Powder Diffr. 32, S9–S15]. Instead of keeping a constant azimuthal direction of the incident beam on the thin film sample, the current proposed variation maintains a constant azimuthal direction of the scattering vector projection on the thin film sample. The variation is named `ω–φ′ compensated GID in side-inclination mode' and enables d-spacing measurements along the same azimuthal direction. An Excel spreadsheet is included for readers to plan the measurement and to calculate the residual stress for the planned sample azimuthal direction. Anisotropic residual stresses of a polycrystalline NiFe thin film on an Si 001 substrate are measured by combining this method with phi rotations. Highly automated data analysis templates are developed using DIFFRAC.TOPAS v7 launch mode to calculate residual stress for all planned azimuthal directions sequentially. A pole figure file in simple text format is also generated from the same data set using DIFFRAC.TOPAS v7 launch mode, and can be directly imported into DIFFRAC.TEXTURE v4.1 for further texture analysis. Corrections for the incident-beam refraction have been implemented in both data analysis models.

Temperature-dependent site selection of boron doping in chemically derived graphene

Site dependent light element doping in graphene can lead to exciting phenomenological prospects such as tunable bandgap, enhanced electron phonon coupling and anomalous transport properties for superconductivity, ferromagnetism and catalysis. However, they can lead to more additional defect sites and strain dependent effects as a residual fallout of the process and remains open to interpretations. In this work, we delineate a spectroscopic approach combined with ab-initio results to decipher these factors by using a prototypical in-situ boron doped reduced graphene oxide sample specimens and tuning them from low to moderate hole doping concentrations. The selectivity of doping configurations (BC3, BCO2 and BC2O) as well as their concentration is varied by regulating the annealing temperature (up to 1000 °C). We find a competitive relationship between the dopant and the residual surface oxygen atoms with gradual transformation of favorable doping configuration from out of plane to in-plane (substitutional) with increasing temperature. Furthermore, simultaneous induction of point defects and strain related effects in graphene lattice were also observed with increase in doping concentration. This led to anomalous bandgap crossover at high temperatures in boron doped graphene in comparison to the thermally reduced counterpart which could be important for electronic and transport applications.

Scaling theory of three-dimensional magnetic reconnection spreading

We develop a first-principles scaling theory of the spreading of three-dimensional (3D) magnetic reconnection of finite extent in the out of plane direction. This theory addresses systems with or without an out of plane (guide) magnetic field, and with or without Hall physics. The theory reproduces known spreading speeds and directions with and without guide fields, unifying previous knowledge in a single theory. New results include the following: (1) reconnection spreads in a particular direction if an x-line is induced at the interface between reconnecting and non-reconnecting regions, which is controlled by the out of plane gradient of the electric field in the outflow direction. (2) The spreading mechanism for anti-parallel collisionless reconnection is convection, as is known, but for guide field reconnection it is magnetic field bending. We confirm the theory using 3D two-fluid and resistive-magnetohydrodynamics simulations. (3) The theory explains why anti-parallel reconnection in resistive-magnetohydrodynamics does not spread. (4) The simulation domain aspect ratio, associated with the free magnetic energy, influences whether reconnection spreads or convects with a fixed x-line length. (5) We perform a simulation initiating anti-parallel collisionless reconnection with a pressure pulse instead of a magnetic perturbation, finding spreading is unchanged rather than spreading at the magnetosonic speed as previously suggested. The results provide a theoretical framework for understanding spreading beyond systems studied here and are important for applications including two-ribbon solar flares and reconnection in Earth's magnetosphere.

Extremely flat band in antiferroelectric bilayer α-In2Se3 with large twist-angle

The moiré-pattern with slightly interlayer-twisted bilayer two-dimensional (2D) materials has recently been receiving substantial attention. One of the major characters for these intriguing structures is the appearance of low-energy ultra-flat bands and thus a package of new physics associated with strong electron correlation emerges. However, such new physics may become vague unless the twist-angle θ is sufficiently small such as θ ∼ 1°, making practical applications and control-flexibility hard to handle. In this work, we explore the possible flat-band moiré physics in recently concerned 2D bilayer α-In2Se3 which is antiferroelectric with sublayer out-of-plane (OP) polarizations, addressing the potential role of polarization-bound charges in modulation of electron–electron correlation and interlayer hybridization, based on the extensive first-principles calculations. On one hand, it is found that the low energy band becomes extremely flat in the bilayer α-In2Se3 moiré-pattern with relatively large twist-angle, e.g. θ = 13.17°, which is more easily accessible experimentally. On the other hand, the impact of the sublayer OP polarizations on the band structure is asymmetric, and the flattening effect is much more remarkable for the end-to-end polarization alignment but weaker for the head-to-head alignment. This work thus opens a broad roadmap for technological access to artificial fabrication of novel moiré-patterned 2D materials by means of low-dimensional ferroelectricity.