Low-energy Band Research Articles

Facile synthesis of a novel CeCO3OH@(H/C–CdS) catalyst with synergistic effect of heterophase junction and heterojunction for enhanced visible-light photocatalytic degradation efficiency at room temperature

A new CeCO3OH@(hexagonal/cubic phases–CdS) (CeCO3OH@(H/C–CdS)) composite catalyst was facilely synthesized by a simple microinjection titration–stirring method, in which CdS nanoparticles were dispersed on the surface of CeCO3OH nanolines. The optimal conditions for the preparation of composite catalysts with high photocatalytic performance were determined by single-factor experiments and response surface experiments. Under these conditions, the degradation rate of 30 mL 2.000 g/L rhodamine B (Rh B) by CeCO3OH@(H/C-CdS) in a photocatalytic reaction for 1 h at 25 °C was up to 86.81 % and its degradation rate in a photocatalytic reaction for 150 min was up to 99.62 %. The degradation rate could be maintained above 80 % even after six times recycling. Especially, the photocatalytic degradation efficiency of 2.000 g/L Rh B on the composite catalyst under sunlight and at room temperature for 30 min reached 97.66 %. Meanwhile, the large size of CeCO3OH considerably alleviated the agglomeration of CdS, providing more adsorption and active sites for visible light-mediated degradation of Rh B. Importantly, the Z-scheme charge transfer realized by CdS and CeCO3OH enhanced the efficient separation of photogenerated electrons and holes, and successfully inhibited the recombination of photogenerated electrons with holes. At the same time, owing to the low energy band difference between the two phases of CdS, charge was transferred between the hexagonal and cubic phases, leaving more effective photogenerated charge to participate in the degradation of Rh B. The synergism of the heterophase junction and heterojunction and the presence of oxygen and sulfur vacancies considerably enhanced the degradation performance of the catalyst. Thus, this study provides a new strategy for the modification and enhanced visible-light catalysis performance of CdS-based catalysts.

A series of tetraphenylene-acetonitrile AIE compounds with D-A-D′ structure for drugs delivery systems of paclitaxel: Synthesis, structure-activity relationship and anti-tumors effect

Aggregation-induced emission (AIE) materials are attracting great attention in biomedical fields such as sensors, bioimaging, and cancer treatment, et al. due to their strong fluorescence emission in the aggregated state. In this contribution, a series of tetraphenylene-acetonitrile AIE compounds with D-A-D′ structures were synthesized by Suzuki coupling reaction and Knoevenagel condensation, and their relationship of chemical structure and fluorescence properties was investigated in detail, among which TPPA compound was selected as the monomer owing to the longest emission wavelength at about 530 nm with low energy band gap ΔE 3.09 eV of neutral TPPA and 1.43 eV of protonated TPPA. Novel amphiphilic AIE PEG-TA copolymers were prepared by RAFT polymerization of TPPA and PEGMA with about 1.44×104 Mw and narrow PDI, and the molar ratio of TPPA in the PEG-TA1 and PEG-TA2 copolymers was about 23.4 % and 29.6 %. The as-prepared PEG-TA copolymers would self-assembled in aqueous solution to form core-shell structures with a diameter of 150–200 nm, and their emission wavelength could reversibly convert from 545 nm to 650 nm with excellent pH sensitivity. The CLSM images showed that the PEG-TA FONs and PTX drugs-loaded PTX-TA FONs could be endocytosed by cells and mainly enriched in the cytoplasm, and CCK-8 results showed that the PEG-TA FONs had excellent biocompatibility but PTX-TA FONs had high inhibition ratio for A549 cells, moreover, the flow cytometry also showed that PTX-TA FONs could result in the apoptosis of A549 cells with some extent anti-tumor effect.

Modeling Blazar Broadband Emission with Convolutional Neural Networks. II. External Compton Model

In the context of modeling spectral energy distributions (SEDs) for blazars, we extend the method that uses a convolutional neural network (CNN) to include external inverse Compton processes. The model assumes that relativistic electrons within the emitting region can interact with and up-scatter external photons originating from the accretion disk, the broad-line region, and the torus, to produce the observed high-energy emission. We trained the CNN on a numerical model that accounts for the injection of electrons, their self-consistent cooling, and pair creation-annihilation processes, considering both internal and all external photon fields. Despite the larger number of parameters compared to the synchrotron self-Compton model and the greater diversity in spectral shapes, the CNN enables an accurate computation of the SED for a specified set of parameters. The performance of the CNN is demonstrated by fitting the SED of two flat-spectrum radio quasars, namely 3C 454.3 and CTA 102, and obtaining their parameter posterior distributions. For the first source, the available data in the low-energy band allowed us to constrain the minimum Lorentz factor of the electrons, γmin , while for the second source, due to the lack of these data, γmin=102 was set. We used the obtained parameters to investigate the energetics of the system. The model developed here, along with one from Bégué et al., enables self-consistent, in-depth modeling of blazar broadband emissions within a leptonic scenario.

Is the Presence of Sn2+ a Crucial Factor for the Generation of Low Thermal Conductivity in Tin-Based Sulfides?

Comprehending the relationship between crystal structures and transport properties is crucial to develop materials with improved electrical and thermal properties for thermoelectric applications. In this article, we report on the complex crystal structure and physical properties of Cr2Sn3S7, a n-type magnetic semiconductor with a low energy band gap and low thermal conductivity. Importantly, we demonstrate that the high level of structural complexity is related to the coexistence of two sublattices: a host lattice, [Cr4Sn2S11]2-, characterized by a mixed Sn4+/Cr3+ occupancy of its cationic sites, and a guest lattice characterized by [Sn4S3]2+ chains, containing Sn2+ cations only, closely related to the ones encountered in the orthorhombic SnS compound. By combining experiments including X-ray diffraction with ab initio calculations of electrons and phonons, we succeeded to elucidate the origin of the low thermal conductivity in Cr2Sn3S7. We demonstrate that the low dimensionality of the [Sn4S3]2+ chains, which generates weak Sn···S interactions with the 3D host lattice, is induced by the lone pair stereochemical activity of Sn2+. This lattice softening favors strong anisotropic vibrations at low frequencies, highlighting the primordial role played by Sn2+ cations in both crystal structure dimensionality and low thermal conductivity in tin-based sulfides.

Impacts of electric gating and divacancies on optical absorption spectra of zigzag buckling silicene nanoribbons

In this study, by combining the tight-binding description with the gradient approximation, we investigated the impacts of electric gating and divacancies on the optical characteristics of zigzag buckling silicene nanoribbons. Our results show that the back-gate electric potential tends to shift the peak structure to higher frequencies in the free-defective structures, while the side-gate electric potentials intensify the intensity of the excitation channels obeying the selection rule ΔJ=even. In particular, applying the potentials in a suitable range can improve the optical absorption efficiency at a certain frequency with the back gate or widen the threshold absorption intensity from Jv=1 to Jc=1 with the side gates. Besides, the defective structures' absorption spectra exhibit richer features than the perfect one, with the appearance of new optical excitations due to the transitions between the local minimum or maximum in the low-energy bands around the Fermi level. Moreover, applying electric gating in defective structures can also tune the absorption spectra with additional features.

Optical and electrochemical studies on single-phase ZnSnO3 nanostructures—A photosensitive approach

A sol-gel-combustion reaction approach is used to synthesize nanocrystalline, single-phase ZnSnO3 phosphor. XRD with the Rietveld refinement investigation reveals a previously unreported orthorhombic structure of ZnSnO3. FTIR analysis confirms the formation of the ZnSnO3 phase. Microstructural SEM and TEM examinations affirm the petal-like morphology of the ZnSnO3 nanostructure. UV-DRS analysis signifies ZnSnO3 as a semiconducting material with a lowest energy band gap of 2.94 eV, which has never been recorded before. Photoluminescence (PL) studies reveal defect-related emission in ZnSnO3. Cyclic voltammetry measurements confirm the redox process and photo-generated carrier recombination via defect levels. ZnSnO3 is identified as a p-type semiconductor by Mott-Schottky analysis. When irradiated with 397 nm UV light, the semiconducting nanostructures emit near-white light. Finally, the investigation of ZnSnO3 nanopowder for latent fingerprint impressions reveals an unusual diffuse reflection and high-resolution images under a sodium vapour lamp and LASER-LED illumination.

Evidence for a Cyclotron Absorption Line and Spectral Transition in EXO 2030+375 during the 2021 Giant Outburst

Based on Insight-HXMT observations of EXO 2030+375 during its 2021 giant outburst, we report the analysis of pulse variations and the broadband X-ray spectrum, and find the presence of a potential cyclotron resonant scattering feature (CRSF) with the fundamental line at ∼47 keV from both average spectra and phase-resolved spectroscopy. During the outburst, the source reached an X-ray luminosity of ∼1038 erg s−1 from 2 to 105 keV at a distance of 7.1 kpc. The X-ray pulsar at the spin period of 41.27 ± 0.61 s exhibits complex timing and spectral variations with both energy and luminosity during the outburst. The shapes of the pulse profiles show the single main peak above ∼20 keV, while appearing to exhibit multipeak patterns in low-energy bands, and the transition of the 10–20 keV pulse profiles from multipeak to single peak is observed at ∼0.8 × 1038 erg s−1, which suggests the evolution from the subcritical luminosity (pencil-beam dominated) to the supercritical luminosity (fan-beam dominated) regime. A dip structure before the energy of the CRSFs is found in the pulse fraction–energy relation of EXO 2030+375 near the peak luminosity. A detailed analysis of spectral parameters showed that the power-law photon index exhibits three distinct trends as luminosity increases, and these spectral changes also signify a spectral transition from subcritical to supercritical regimes. The critical luminosity infers a magnetic field of ∼(4.8−6.0) × 1012 G, which supports the presence of the cyclotron line at ∼47 keV. A Comptonization model applied for the broad X-ray spectra during the outburst also suggests the surface magnetic field ranging from ∼(5−9) × 1012 G.

Novel porphyrin photocatalyst intertwined with ionic liquid and sulfonic acid groups for facile photo-transesterification of used frying oil

Visible light mediated transesterification of Used Frying Oil (UFO) with novel porphyrin as recyclable photocatalyst was explored in a homemade photoreactor. Porphyrin photocatalyst intertwined with ionic liquid and sulfonic acid (PPcILS) was synthesized by reaction of 2-((4-formylbenzylidene)amino)-1sulfopyridin-1-ium chloride [B] and pyrrole (1:1 ratio) in AcOH under reflux condition. PPcILS photocatalyst was confirmed by various characterization techniques. Box-Behnken Design was utilized to determine the influence of photocatalytic reaction conditions: quantity of photocatalyst, duration, intensity of light, and molar ratio. The appreciable proton level (H0 = 0.9571) and lower energy band gap (1.25 eV) of PPcILS, verified by photo-transesterification of UFO (palm-oil) to biodiesel with 90.23 % yield under irradiation of 5 W LED, 20 mg photocatalyst and UFO: ethanol (01:10) molar ratio in 15 h. The physicochemical properties of B15-Blended-Diesel and commercial Diesel were found to be comparable. Likewise, engine performance, combustion, and emission parameters of B15-Blended-Diesel was found very close to neat Diesel.

Exploring the electronic structure of tetrathienylethene derivatives for OLED applications: A theoretical study

AbstractThe B3LYP/6‐31G(d,p) method is applied to investigate the structural and electronic properties of tetrathienylethene (TTE) derivatives, specifically for the properties of 14 distinct TTE derivatives. The results indicate that the T1–T14 derivatives exhibit numerous advantages over the parent TTE compound. Notably, substituents predominantly impact the LUMO energy level of the TTE parent compound. Additionally, all modified molecules exhibit lower energy band gaps (Egap) and improved charge transfer capacity relative to TTE. These findings suggest that the T1–T14 derivatives may be promising candidates for use as materials in OLED applications. The values of chemical hardness (η) indicate that all compounds T1–T14 manifest greater softness relative to the parent compound TTE. This correlation aligns with the calculated Egap values, wherein compounds T1–T14 consistently exhibit smaller Egap values compared to the TTE compound. These research findings indicate that compounds T1 and T10 display remarkable and harmonious charge transfer capabilities. This is evident from their corresponding values of λh and λe, which stand at 0.39/0.41 and 0.41/0.41 eV, respectively. Remarkably, compound T1 exhibits the most pronounced absorption peak, occurring at a wavelength of 441 nm. This absorption is accompanied by the highest oscillator strength recorded for the compound, reaching a value of 0.638.

FTIR Spectroscopy and Microstructural Study of Fe Doped Calcium Copper Titanate (CCTO)

Objectives : The analysis of present material is to reveal the effect of Fe atom by replacing the Ti atom in CCTO for chemical properties. Methods: Pure and Fe doped CaCu3Ti4-xFexO12 (x=0.05, 0.10, and 0.15) CCTO ceramics were synthesized by solid-state reaction route and calcination was done at 930°C for 12 hrs with heating rate of 4°C/min. The phase structure of samples was confirmed by X-ray Diffraction (XRD) and found single phase calcium copper titanate. Morphology of all samples was investigated by scanning electron microscopy. Absorption band have been also recorded for all samples. Findings: The structure remains cubic by doping of Fe atom in place of Ti atom. The average size of all the samples were lies between 1-1.3µm. Novelty: The bond strength becomes stronger as the doping of Fe atom takes place. The large absorption band is found in the range 380-700 cm-1. The peak of large band is shifted towards lower wave number. These higher wavelengths can be used in water pollutants. The increased volume size of samples shows lower energy band gap. This lower energy band gap enhanced the electrical properties. Keywords: FE­SEM, XRD, FTIR, EDS, CCTO

Establishing Li-acetylide (Li2C2) as functional element in solid-electrolyte interphases in lithium-ion batteries

Previously, lithium-acetylide (Li2C2) had been identified as electrolyte degradation product on lithium-metal based electrodes using Raman spectroscopy. This raised the question, if Li2C2 is also be formed on graphitic electrodes in lithium-ion batteries without lithium metal present. In order to shed light on this research question, we performed a series of in situ Raman experiments with graphitic electrodes in half- and full-cell configuration. The recorded cell potential dependent spectra clearly prove the presence of Li2C2 in the lithiated state of the electrodes, but the according peak vanishes when delithiating. This observation indicates a somewhat reversible process involving Li2C2. Several chemical/electrochemical reactions are in question to contribute to this effect. With respect to its properties and potential role in the solid-electrolyte interphase (SEI) DFT calculations of Li2C2-nanoclusters were performed, which revealed an exceptionally low energy band gap, hence a remarkable electric conductivity. In conjunction with a relatively high ionic conductivity, Li2C2 appears to play a key role in the degradation of lithium-ion batteries, which had not yet been revealed nor taken into account in simulations of the interphase.

Preparation and Rheological Properties of the PVA/CMC/Gel Composite for Mining.

A composite gel material with an interpenetrating network structure was formed using the chemical cross-linking method. The viscosity, yield stress, and thixotropy of a poly(vinyl alcohol)/carboxymethyl cellulose/gelatin (PVA/CMC/Gel) composite gel slurry with different ratios were tested using a viscometer, and the interaction between the surface of the gelling agent and the cross-linking agent was analyzed by calculating the frontline orbital energy of a single polymer material molecule. The seepage diffusion characteristics of the composite gel in a goaf were then studied through a numerical simulation. The results indicate that the PVA/CMC/Gel composite gel exhibits shear thinning behavior following the power law model and behaves as a pseudoplastic fluid. The optimal ratio for the composite gel at 30 °C is determined as follows: 30 wt % for the gelling agent (PVA/(Gel + CMC) = 20:10), 4 wt % for the cross-linking agent, 3.09 wt % for the carbide slag, 7.5 wt % for the alcohol amine solution, and 0.5% sodium dodecyl sulfonate + 0.1% alkyl glycoside for the foaming agent. Gel exhibits the lowest energy band gap (0.096 eV), indicating strong reaction activity and strong reaction with the cross-linking agent (sodium tetraborate). PVA has the largest energy band gap (0.238 eV), strong molecular stability, and weak reaction with the cross-linking agent (sodium tetraborate). When the dip angle of the goaf is 4° and the injection time is 40 min, the composite gel tends to diffuse more easily along the dip. The investigation into the rheological properties of the PVA/CMC/Gel composite gel holds significant importance in the design of coal mine pipeline transportation and understanding diffusion flow in goaf.

Effects of TiO2 Nanoparticles Synthesized via Microwave Assistance on Adsorption and Photocatalytic Degradation of Ciprofloxacin.

In this study, the optimal microwave-assisted sol-gel synthesis parameters for achieving TiO2 nanoparticles with the highest specific surface area and photocatalytic activity were determined. Titanium isopropoxide was used as a precursor to prepare the sol (colloidal solution) of TiO2. Isopropanol was used as a solvent; acetylacetone was used as a complexation moderator; and nitric acid was used as a catalyst. Four samples of titanium dioxide were synthesized from the prepared colloidal solution in a microwave reactor at a temperature of 150 °C for 30 min and at a temperature of 200 °C for 10, 20, and 30 min. The phase composition of the TiO2 samples was determined by X-ray diffraction analysis (XRD) and Fourier-transform infrared spectroscopy (FTIR). Nitrogen adsorption/desorption isotherms were used to determine the specific surface area and pore size distributions using the Brunauer-Emmett-Teller (BET) method. The band-gap energy values of the TiO2 samples were determined by diffuse reflectance spectroscopy (DRS). The distribution of Ti and O in the TiO2 samples was determined by SEM-EDS analysis. The effects of adsorption and photocatalytic activity of the prepared TiO2 samples were evaluated by the degradation of ciprofloxacin (CIP) as an emerging organic pollutant (EOP) under UV-A light (365 nm). The results of the photocatalytic activity of the synthesized TiO2 nanoparticles were compared to the benchmark Degussa P25 TiO2. Kinetic parameters of adsorption and photocatalysis were determined and analyzed. It was found that crystalline TiO2 nanoparticles with the highest specific surface area, the lowest energy band gap, and the highest photocatalytic degradation were the samples synthesized at 200 °C for 10 min. The results indicate that CIP degradation by all TiO2 samples prepared at 200 °C show a synergistic effect of adsorption and photocatalytic degradation in the removal process.

Interplay between Theory and Photophysical Characterization in Symmetric α-Substituted Thienyl BODIPY Molecule.

4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based molecules have emerged as interesting materials for optoelectronic applications due to the possibility to easily fine-tune their photophysical and optical properties, dominated by two main absorption bands in the visible range. However, no studies have been reported on the nature of these spectral features. By means of ultrafast spectroscopy, we detect intramolecular energy transfer in a spin-coated film of di-thieno-phenyl BODIPY (DTPBDP) dispersed in a polystyrene matrix after pumping the high-energy absorption band. The same effect is not present upon pumping the lowest-energy band, which instead allows the achievement of efficient amplified spontaneous emission. Density functional calculations indicate the different nature of the two main absorption bands, explaining their different photophysical behavior.

Microwave Absorption Properties of Hexagonal Ba3(VO4)2 through Zn Doping: A Comprehensive Analysis of Ba3–xZnx(VO4)2

The current study explores the influence of Zinc (Zn) doping on the crystallography, optical behavior, dielectric properties, and microwave absorption characteristics of hexagonal Barium Vanadate (Ba3(VO4)2). Samples were systematically synthesized with Zn doping concentrations of x = 0, 0.05, 0.1, 0.15, and 0.2 mol%, resulting in Ba3–xZnx(VO4)2. Employing various characterization techniques, the alterations in structural, optical, and electrical responses due to incremental Zn incorporation are reported. The UV–VIS DRS absorption spectra reveal a decrease in energy bandgap with increasing concentration of Zn. The lowest optical energy band gap observed was 3.65 eV for x = 0.2 mol% Zn. Notably, at a thickness of 6.5 mm, the material achieved a high reflection loss of −82.37 dB at 12.47 GHz for x = 0.05 mol% of Zn. Similarly, the same material configuration exhibited a maximum effective absorption bandwidth (EAB) of 5.01 GHz, spanning a frequency range from 12.24 to 17.25 GHz when the thickness was set to 5.5 mm. Furthermore, as the Zn concentration increased from x = 0.05 to 0.2 mol%, a decreasing trend in reflection loss was observed, correlating well with the dielectric parameters of samples with different Zn concentrations. The work provides insightful correlations between Zn doping levels and the material’s performance in potential applications ranging from optoelectronics to electromagnetic wave absorption.

Multiband Nonthermal Radiative Study of PeVatron Candidate Pulsar Wind Nebula HESS J1849-000

Pulsar wind nebula HESS J1849-000 is one of the sources that may emit PeV γ-ray photons based on the recent measurement by the Tibet Air Shower Array and the Large High Altitude Air Shower Observatory. We use a time-dependent model to investigate the nonthermal radiative properties of HESS J1849-000. Observed multiband data are produced well by relativistic leptons through synchrotron radiation and inverse Compton processes, and the particle transport and cooling processes are analyzed. Our results show that the particle adiabatic loss dominates over the synchrotron loss and inverse Compton losses, and the particle advection dominates over diffusion for the low-energy band. On the other hand, the particle synchrotron loss dominates over the adiabatic loss and inverse Compton losses, and the diffusion dominates over advection for the high-energy band. Furthermore, particle transport would be playing a significant role in the low-energy band, whereas the particle cooling processes may play a more important role in the high-energy band. The current diffusion coefficient 3.4 × 1026 cm2 s−1 at an electron energy of 1 TeV is derived, which implies a slow diffusion mechanism may occur within the nebula. More importantly, our model suggests that the particle's maximum energy is 3.6 PeV, which makes HESS J1849-000 a PeVatron candidate.

CdTe XG-Cam: A new high-resolution x-ray and gamma-ray camera for studies of the pharmacokinetics of radiopharmaceuticals in small animals.

The recent emergence of targeted radionuclide therapy has increased the demand for imagers capable of visualizing pharmacokinetics in developing radiopharmaceuticals in the preclinical phase. Some radionuclides emit hard x-rays and gamma-rays below 100 keV, in which energy range the performance of conventional NaI scintillators is poor. Multipinhole collimators are also used for small animal imaging with a good spatial resolution but have a limited field of view (FOV). In this study, a new imager with high sensitivity over a wide FOV in the low-energy band ( 100 keV) was developed for the pharmacokineticstudy. We developed an x-ray and gamma-ray camera for high-resolution spectroscopy, named "CdTe XG-Cam," equipped with a cadmium telluride semiconductor detector and a parallel-hole collimator using a metal 3D printer. To evaluate the camera-system performance, phantom measurements with single and dual nuclides ( , , and were performed. The performance for in vivo imaging was evaluated using tumor-bearing mice to which a nuclide ( or administered. We simultaneously obtained information on and , which emit emission lines in the low-energy band with peak energies close to each other (23-26 keV for and 27-31 keV for , and applied an analytical method based on spectral model fitting to determine the individual radioactivities accurately. In the small animal imaging, the distributions of the nuclide in tumors were accurately quantified and time-activity curves in tumors areobtained. The demonstrated capability of our system to perform in vivo imaging suggests that the camera can be used for applications of pharmacokineticsresearch.

Magic-angle twisted bilayer graphene under orthogonal and in-plane magnetic fields

We investigate the effect of a magnetic field on the band structure of bilayer graphene with a magic twist angle of 1.08∘. The coupling of a tight-binding model and the Peierls phase allows the calculation of the energy bands of periodic two-dimensional systems. For an orthogonal magnetic field, the Landau levels are dispersive, particularly for magnetic lengths comparable to or larger than the twisted bilayer cell size. A high in-plane magnetic field modifies the low-energy bands and gap, which we demonstrate to be a direct consequence of the minimal coupling.

A comprehensive computational investigation on the physical properties of the chalcogenide ternary Y2ZnX4 (Y = In, Ga; X = S, Se) compounds

In this study, the structural, elastic, vibrational, electronic, optical, thermodynamic, and thermoelectric properties of the chalcogenide ternary Y2ZnX4 (Y = In, Ga; X = S, Se) compounds are comprehensively investigated using the pseudopotential plane-wave (PP-PW) and full-potential linearized augmented plane wave (FP-LAPW) methods. The analysis of elastic and vibrational properties reveals the dynamic and mechanical stability of these compounds. The calculated energy band gaps, ranging from 1.47 eV (Ga2ZnSe4) to 2.55 eV (In2ZnS4) in the visible spectrum, decrease as X atoms are substituted with S to Se. All examined compounds demonstrate favorable optical absorption (α > 105 cm−1) in the ultraviolet region. Notably, Ga2ZnSe4 exhibits absorption red-shift towards the visible region at hν = 2.76 eV due to its lower energy band gap, making it a promising candidate for solar cells. The three-dimensional representation of Young's modulus indicates significant deviation from sphericity, revealing anisotropic behavior in all compounds. Pugh's ratio, Poisson's ratio, and Cauchy's pressure analysis suggest ductile behavior in all four chalcogenide ternary compounds. Additionally, all compounds, except In2ZnS4, display auxetic properties. Finally, the calculated thermoelectric properties identify Ga2ZnS4 and In2ZnS4 as promising candidates for high-performance thermoelectric applications, with high Seebeck coefficients of 1848 and 1936 μV/K, respectively, and ZT values approaching unit.

Moiré band renormalization due to lattice mismatch in bilayer graphene

We investigated the band renormalization caused by the compressive-strain-induced lattice mismatch in parallel AA stacked bilayer graphene using two complementary methods: the tight-binding approach and the low-energy continuum theory. While a large mismatch does not alter the low-energy bands, a small one reduces the bandwidth of the low-energy bands along with a decrease in the Fermi velocity. In the tiny-mismatch regime, the low-energy continuum theory reveals that the long-period moiré pattern extensively renormalizes the low-energy bands, resulting in a significant reduction of bandwidth. Meanwhile, the Fermi velocity exhibits an oscillatory behavior and approaches zero at specific mismatches. However, the resulting low-energy bands are not perfectly isolated flat, as seen in twisted bilayer graphene at magic angles. These findings provide a deeper understanding of moiré physics and offer valuable guidance for related experimental studies in creating moiré superlattices using two-dimensional van der Waals heterostructures.