Band Gap Analysis Research Articles

Computational and optoelectronic investigations of red-emissive europium (III) β-diketonate with n-donor ligands for display applications

Europium complexes exhibiting red luminescence were prepared by employing β-diketone as main ligand and 1,10-phenanthroline as an additional ligand. Various methods, including 1H NMR, IR spectroscopy and analysis of optical band gap were employed to examine these complexes. The luminescent photophysical properties were investigated using PL spectroscopy and theoretical calculations were conducted to explore radiative transitions probabilities and Judd-Ofelt (J-O) parameters for transitions of type 5D0 → 7F2, 4. J-O parameters were determined using the JOES computer program and results were in good agreement with the outcomes obtained experimentally. The luminescence analysis results have verified the vibrant, single-color red emission of the prepared complexes. The band gap of ternary europium complexes, determined optically, electronically, and theoretically, falls within the range of 3–4 eV. This similarity indicates that these complexes are potentially suitable as semiconductor materials. The results from absorption, electrochemical and photophysical analyses indicate the potential use of synthesized complexes in lighting and display applications.

An Analysis of Bandgaps in the Spectrum of Acoustic-Gravity Waves in an Isothermal Atmosphere

An Analysis of Bandgaps in the Spectrum of Acoustic-Gravity Waves in an Isothermal Atmosphere

Bandgap analysis of periodic composite plates considering fluid–structure coupling

This article presents a novel approach for predicting vibration bandgaps in periodic composite plates with fluid–structure interaction (FSI) using a unit cell-based finite element model. The novelty of our approach lies in the formulation of a fluid-induced added mass matrix, which integrates the Bloch periodic boundary condition, allowing for the incorporation of the fluid’s inertial effect in the context of unit cell-based bandgap analysis. We therefore construct a unit cell model comprising a composite Mindlin plate which integrates periodic FSI effects with the simultaneous application of Bloch conditions on both the structure and the fluid domains. Subsequently, we studied a set of periodic composite plates with FSI effects on one or both sides, thereby assessing the influence of the fluid properties such as density and the fluid domain dimension on the structure vibration. The bandgap prediction is compared with the frequency response simulations which involve diversified microstructure designs. The obtained results provide indications regarding the effectiveness and applicability of the proposed numerical methodology.

Size and Temperature Effects on Band Gap Analysis of a Defective Phononic Crystal Beam

In this paper, a new defective phononic crystal (PC) microbeam model in a thermal environment is developed with the application of modified couple stress theory (MCST). By using Hamilton’s principle, the wave equation and complete boundary conditions of a heated Bernoulli–Euler microbeam are obtained. The band structures of the perfect and defective heated PC microbeams are solved by employing the transfer matrix method and supercell technology. The accuracy of the new model is validated using the finite element model, and the parametric analysis is conducted to examine the influences of size and temperature effects, as well as defect segment length, on the band structures of current microbeams. The results indicate that the size effect induces microstructure hardening, while the increase in temperature has a softening impact, decreasing the band gap frequencies. The inclusion of defect cells leads to the localization of elastic waves. These findings have significant implications for the design of microdevices, including applications in micro-energy harvesters, energy absorbers, and micro-electro-mechanical systems (MEMS).

Controlled doping rates of graphene oxide in aluminum for high electrical performance and oxygen reduction reaction

The brush coating method allows the advantage of being able to produce thin films simply and quickly. This study introduces a method for thin-film production by brushing a solution containing graphene doped in Al2O3 using the sol–gel method. Graphene oxide (GO) is suitable for semiconductors with bandgap values of about 1.7 eV at room temperature, and the characteristics of the thin films were analyzed according to the doping ratio. First, X-ray photoelectron spectroscopy measurements were obtained to analyze the chemical composition of the thin-film surface. Since graphene is a carbon isomer, the characteristic of oxygen vacancies was confirmed by the increasing C–C bond intensity with increasing GO doping concentration. In addition, Raman analysis was performed to analyze the concentration of molecular groups of compounds for defects in graphene. Thereafter, through atomic force microscopy measurements, as the graphene doping ratio increased, the average roughness increased from 1.785 to 33.67, the residual DC voltage also increased by about 48.42 %, and the polar anchoring energy also increased by about 16.33 %. In addition, response-time–transmittance measurements were performed to measure the electro-optical properties of the thin film, and excellent Vth and stable response speed were obtained. Additionally, the validity of the results was supported through bandgap analysis. Finally, the degree of alignment of liquid–crystal molecules on the film surface was confirmed by polarized optical microscopy and pretilt angle measurements, and the suitability of the thin film for display devices was shown via transmittance measurements. As a result, GO:Al2O3 hybrid thin film is an excellent candidate for use as an alignment film for solar energy, secondary batteries, and next-generation liquid crystal displays.

A novel Z-scheme heterojunction photocatalyst CeO2@WO3 nanocomposite with enhanced visible-light photocatalytic performance for wastewater treatment by cephalexin antibiotic degradation: Process optimization

Considering growing global environmental concerns, there is a heightened focus on expediting the synthesis of highly efficient catalytic materials to address these challenges effectively. Herein, a novel CeO2@WO3 heterojunction photocatalyst was synthesized using an ultrasonic-assisted method for the environmentally friendly degradation of cephalexin (CPX) under visible light. The optimized photocatalyst synthesis condition was achieved by assessing the influence of effective parameters, including the CeO2 content (5–25 wt%) and calcination temperature (300–600 °C), employing the RSM method. The synthesized photocatalysts were comprehensively characterized through XRD, SEM, TEM, EDS-mapping, BET, FTIR, and UV–Vis band gap analysis. Using optimal photocatalyst (CeO2 content: 15.78 %, calcination temperature: 440.59 °C, and ultrasonic power: 80 W), the influence of four critical variables on CPX degradation was thoroughly investigated via RSM-CCD. The maximum CPX degradation efficiency of 98.8 % was attained under the following optimal conditions: CPX concentration: 20.00 mg/L, solution pH: 6.79, photocatalyst dosage: 0.019 g/L, and visible light time: 94.82 min. Statistical analysis confirmed the accuracy of the regression model based on empirical data. The CeO2@WO3 heterojunction demonstrated substantial Chemical Oxygen Demand (COD) removal, reaching 73.26 % during the mineralization of CPX, surpassing the outcomes of previous studies. Trapping experiments and EPR analysis indicated the crucial involvement of hydroxyl radicals and superoxide radicals as highly active species due to their non-selective oxidation capabilities. Furthermore, a Z-scheme charge transfer mechanism was proposed to elucidate the enhanced photocatalytic activity. Identifying degradation intermediates was accomplished through HPLC-MS analysis, leading to a plausible pathway for CPX degradation. Overall, CeO2@WO3 exhibited excellent stability and could endure five cycles with minimal cerium leaching, highlighting its effectiveness in decomposing organic contaminants.

Red-emitting Eu3+ activated LaSr2AlO5 phosphor for wLEDs: Crystal structure, photoluminescence, thermal stability, Judd-Ofelt calculation and band-gap analyses

Red-emitting La1-xSr2AlO5:xEu3+ (x = 0.01–0.06) phosphors have been synthesized via gel combustion (GC) approach and their structure and luminescent characteristics were analyzed in detail. The tetragonal crystal structure (I4/mcm space group) of all generated La1-xSr2AlO5:xEu3+ (x = 0.01–0.06) phosphors have been established by X-ray diffraction and rietveld analysis. The shape and size of the phosphor has been examined using transmission electron microscopy (TEM) and the estimated crystallite size was found to be 32–65 nm. Energy Dispersive X-ray (EDX) analysis confirmed the chemical composition of the synthesized materials. The diffuse reflectance spectra (DRS) were used to compute the band gap energies (Eg) of the samples which emerged to be in region of 5.373–6.009 eV. The Eu3+ activated LaSr2AlO5 phosphors produce red emissions at 579, 592, 614, 656 and 708 nm, when excited at 395 nm. These emission bands are caused by 5D0→7FJ (J = 0, 1, 2, 3, 4) electronic transitions of Eu3+ ion. The Judd-Ofelt theory further supports the performance of LaSr2AlO5:Eu3+ phosphors as a red emitting substance with high branching ratio corresponding to 5D0→7F2 transition from Eu3+ center present in the low symmetry site. Computed chromaticity coordinates (x, y) indicate a high degree of color purity in the phosphors, providing additional evidence for the presence of red emission. Temperature dependent emission (PL) spectra revealed good thermal stability of the synthesized nanophosphors with activation energy (Ea) of 0.1384 eV.

A novel frog-like meta-structure with linkage mechanism for low-frequency vibration isolation

Structures with linkage mechanism, which could be widely seen in engineering, usually need to bear a certain load and exhibit ideal vibration isolation performance. One of the key factors affecting the mechanical and vibration properties is the connection behavior of the linkage mechanism. To clarify its influence on the vibration characteristics, a novel frog-like meta-structure by introducing a linkage mechanism into the conventional locally resonant metamaterial with a mass-spring resonator is proposed in the present paper, in which the linkage connection is considered as three types of hinged, fixed and elastic, respectively. The equivalent dynamic model of the meta-structure is established theoretically to calculate the effective material properties, which is then validated numerically through band gap and vibration analysis. The results show that the hinged linkage offers equivalent mass and free vertical displacement, while the fixed linkage provides supporting stiffness, shifting the band gap towards higher frequencies. An appropriate elastic connection can enhance the ‘spring-vibrator’ effect, which in turn can significantly expand the low-frequency vibration suppression range of the structure. Experiments are also conducted corresponding to the different linkage mechanisms, and the dynamic model is verified. This study could provide a new idea for promoting the application of the locally resonant meta-structure with a linkage mechanism in the field of low-frequency vibration isolation.

Bandgap analysis of partial-interaction composite beams periodically attached vibration absorbers

Elastic metamaterials with local resonant components exhibit unique bandgap behavior that can be utilized to control the vibration and noise of mechanical structures. This study aims to introduce the bandgap characteristics into the vibroacoustic control of partial-interaction composite beams (PICBs) widely adopted in civil engineering, aviation, and marine fields. Vibration absorbers are arranged periodically on the beam to generate a bandgap in PICBs, thereby transforming a conventional PICB into a metamaterial beam. An analytical approach is proposed to establish the spectral element (SE) matrix of a metamaterial beam based on the Timoshenko–Ehrenfest beam theory. Specifically, the governing equations of motion for PICBs follow Hamilton's principle. This model considers the effects of shear slip between two-layer sub-beams, shear deformations, and rotary inertia. The SE matrix of PICBs is then constructed and applied to obtain the SE matrix of the metamaterial beam by assembling the SE matrix of the vibration absorbers. Subsequently, the wave finite element (WFE) method is employed to predict the dispersion curve of the infinite metamaterial beam and the dynamic response of the finite metamaterial beam. In a benchmark example, the complex band structure and transmission indicated by the proposed approach are validated compared to those calculated by evaluation formulas of the literature and the finite element method. Lastly, the bandgap behavior for the vibration absorber parameters, lattice constants, and shear connector stiffness is investigated based on the defined dimensionless parameters. These results are valuable for optimizing vibration and noise reduction in PICBs equipped with attached vibration absorbers.

Design and analysis of corner scatter inclusion in photonic crystal-based ring resonator

One of the significant challenges in integrated optical systems is achieving miniaturization. Traditional components can limit the effective utilization of chip area. Devices with distinctive thickness and length characteristics, including the Mach Zehnder interferometer (MZI), the directional coupler, and waveguides, contribute to this issue, limiting the efficient use of chip area. Photonic crystals offer a solution to this problem. The proposed design results in two optical bandgap ranges, from 0.456586 to 0.675819 μm–1 and from 1.12855 to 1.16338 μm–1, both in TE mode with gap widths of 0.219233 and 0.34826 μm–1, respectively. The corresponding wavelength ranges are from 1479 to 2190 nm and 859 to 886 nm. The analysis of field propagation in the photonic crystal ring resonator (PCRR) is carried out using the finite-difference time domain (FDTD) method, while the bandgap analysis is performed by the plane wave expansion (PWE) method. This work primarily focuses on the incorporation of corner scatters in the PCRR. Corner scatters play a crucial role in guiding the field smoothly inside the ring, thus preventing the localization of light within the structure. After the simulation, various attributes were compared for both structures. At a resonant wavelength of 1550 nm, the input intensity is measured as 0.0591 a.u., and the output intensities for with and without corner scatter are 0.0458 and 0.0539 a.u., respectively.

Vertical MSM-type CsPbBr<sub>3</sub> thin film photodetectors with fast response speed and low dark current

Halide perovskites exhibit excellent electrical and optical properties and are ideal candidates for active layers in optoelectronic devices, especially in the field of high-performance photodetection, where they demonstrate a competitive advantage in terms of development prospects. Among them, the all-inorganic perovskite CsPbBr<sub>3</sub> has received widespread attention due to its better environmental stability. It is demonstrated in this work that a vertical MSM-type CsPbBr<sub>3</sub> thin-film photodetector has characteristics of fast response time and ultra-low dark current. The use of a vertical structure can reduce the transit distance of photo carriers, enabling the device to achieve a fast response time of 63 μs, which is two orders of magnitude higher than the traditional planar MSM-type photodetectors with a response time of 10 ms. Then, by spinning a charge transport layer between the p-type CsPbBr<sub>3</sub> and Ag electrodes, effective separation of photocarriers at the interface is realized and physical passivation between the perovskite and metal electrodes is also achieved. Due to the superior surface quality of the spun TiO<sub>2</sub> film compared with the NiO<sub><i>x</i></sub> film, and through Sentaurus TCAD simulations and bandgap analyses, with TiO<sub>2</sub> serving as the electron transport layer, it effectively inhibits the transmission of excess holes in p-type CsPbBr<sub>3</sub>. Consequently, the electron transport layer TiO<sub>2</sub> is more effective in reducing dark current than the hole transport layer NiO<sub><i>x</i></sub>, with a dark current magnitude of only –4.81×10<sup>–12</sup> A at a –1 V bias. Furthermore, this vertical MSM-type CsPbBr<sub>3</sub> thin-film photodetector also has a large linear dynamic range (122 dB), high detectivity (1.16×10<sup>12</sup> Jones), and good photo-stability. Through Sentaurus TCAD simulation, it is found that the charge transport layer selectively blocks carrier transmission, thereby reducing dark current. The simulation results are in good agreement with experimental data, providing theoretical guidance for a more in-depth understanding of the intrinsic physical mechanisms.

LDPE/Bi2O3 nanocomposites: Enhanced mechanical, dielectric, and optical properties

AbstractThis study is focused on investigating the role of bismuth oxide (Bi2O3) nanoparticles to improve structural, optical, electrical, and mechanical properties of low‐density polyethylene (LDPE). For this purpose, Bi2O3 nanoparticles were synthesized by using the solvothermal method and examined by transmission electron microscopes (TEM), x‐ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, and ultraviolet–visible (UV–Vis) light absorption methods. LDPE‐based nanocomposites were prepared by changing the nanoparticle additive ratio in the composite from 0% to 2% by weight. The composites were analyzed in the context of their FTIR spectra, atomic force microscope (AFM) images, UV–Vis light absorption spectra, stress–strain curves, and energy storage abilities. While the AFM findings indicate a smoother surface for the composites, the optical band gap analysis reveals a slightly decreased direct optical band gap energy. The analyses based on dielectric spectroscopy also highlight the LDPE/0.5% n‐Bi2O3 composite in terms of the best energy storage capability. Additionally, the highest Young's modulus, toughness, stress at break, and percentage of strain at break were also recorded for the LDPE/0.5% n‐Bi2O3 composite. In this context, the LDPE/0.5% n‐Bi2O3 composite with improved dielectric and mechanical properties can be suggested as a new promising LDPE‐based nanocomposite with better properties for industrial purposes.

Flexural wave propagation characteristics of metabeam with simultaneous acoustic black hole and local resonator

This paper studies the flexural wave propagation in a metamaterial beam with the coupled acoustic black hole and local resonators (ABHLR). The main objectives are to derive the dynamic stiffness matrix of the coupled ABHLR unit cell and analyse its wave propagation characteristics. Initially, a closed-form solution of Euler–Bernoulli’s beam with an indented acoustic black hole is derived. From this, an exact dynamic stiffness matrix, incorporating local resonator effects, is derived using the spectral element method. Dispersion diagrams are generated by combining Bloch’s theorem with ABHLR transfer matrix. The coupled effects of acoustic black hole (ABH) and local resonator (LR) on the bandgap characteristics are investigated. The coupled ABHLR metamaterial shows either a positive or negative effect on bandgap formations, depending on the parametric values of the unit cell. As a positive effect, for some parametric values, the coupled ABHLR cell simultaneously produces bandgaps at lower frequencies (LR-based) and higher frequency ranges (ABH-based). Similarly, for other parametric value, as a negative effect, the bandgaps of ABHLR cell get merged but the pass bands appear on the overlapping region. This pass-band appears due to the constructive interference of ABH and LR, on each other. However, the attenuation bandgap with a higher attenuation rate is obtained on the overlapping region due to the destructive interference of LR and ABH effect. Finally, the global stiffness matrix of a finite beam with 30 unit cells is developed to analyse the frequency domain response and the results are validated with band gap analysis of the unit cell. The frequency domain response is also validated with finite element simulations using the commercial software. Results show that ABH and LR parameters have to be optimally designed to utilize the attenuation effects and avoid constructive interference due to coupling effects. The coupling of metamaterials can aid in vibration suppression and multiple-frequency filtering in mechanical and aerospace applications.

Longitudinal wave attenuation and bandgap analysis of a novel type hybrid tunable resonator metamaterial

Achieving vibration suppression or wave attenuation of tunable local resonance metamaterials without physical modification of the resonator has received a lot of attention recently. In this paper, a hybrid tunable metamaterial with a resonator containing a lever mechanism, an electromagnetic device, and a feedback system is proposed to achieve tunable bandgap and longitudinal wave attenuation. Unlike ordinary metamaterials, inertial amplification mechanisms and negative stiffness elements are involved in our proposed metamaterials. The function of the electromagnetic device and the feedback control are considered to theoretically derive the dispersion relation. The effective mass, the effective stiffness, the displacement transmission rate, and the band structure of the proposed metamaterial are analyzed, and the contributions of some key parameters on the bandgap are investigated. The accuracy of the analytical band structure is verified by the wave transmittance curves obtained by numerical simulation and the transient displacement response of a single oscillator. The results show that the proposed metamaterial yields broadband tunable bandgap in the low-frequency range, which enables the isolation of low-frequency longitudinal vibrations. This study provides a novel option for constructing integrated metamaterials to achieve vibration suppression and wave attenuation.

Statistically Analyzed Heavy Metal Removal Efficiency of Silica-Coated Cu0.50Mg0.50Fe2O4 Magnetic Adsorbent for Wastewater Treatment.

Even low concentrations of pollutants in water, particularly heavy metals, can significantly affect the ecosystem and human health. Adsorption has been determined to be one of the most effective techniques of removing pollution from wastewater among the various strategies. To remove heavy metals such as Zn2+ and Pb2+, we prepared a silica-coated CuMgFe2O4 magnetic adsorbent using sol-gel method and tested it for wastewater treatment. X-ray diffraction investigation validated the creation of cubic spinel structure, while morphological analysis showed that silica coating reduces the particle size but boosts the surface roughness of the nanoparticles and also reduces the agglomeration between particles. UV-visible spectroscopy indicates a rise in bandgap and magnetic characteristics analysis indicates low values of magnetization due to silica coating. The kinetic and isotherm parameters for heavy metal ions adsorption onto silica-coated Cu0.50Mg0.50Fe2O4 nanoparticles are calculated by applying pseudo-first-order, pseudo-second-order, Langmuir and Freundlich models. Adsorption kinetics revealed that the pseudo-second-order and Langmuir models are the best fit to explain adsorption kinetics. Synthesized adsorbent revealed 92% and 97% removal efficiencies for Zn2+ and Pb2+ ions, respectively.

Defect-Passivated Photosensor Based on Cesium Lead Bromide (CsPbBr3) Perovskite Quantum Dots for Microbial Detection.

A defect-passivated photosensor based on cesium lead bromide (CsPbBr3) perovskite quantum dots (QD) was fabricated using parylene films, and the photosensor was applied for the microbial detection. The CsPbBr3 perovskite QDs were synthesized to be homogeneous in size under thermodynamic control, and the perovskite QD-based photosensor was fabricated using MoS2 flakes as the electron transfer layer. In this work, a parylene film with functional groups was deposited on a photosensor for physical protection (waterproof) and defect (halide vacancy) passivation of the perovskite QD. As the first effect of the parylene film, the physical protection of the perovskite QD from water was estimated by comparing the photosensor performance after incubation in water. As the second effect of the parylene, the interaction between the functional groups of the parylene film and the halide vacancies of the perovskite QDs was investigated through the bandgap, crystal structure, and trap-state density analysis. Additionally, density functional theory analysis on Mulliken charges, lattice parameters, and Gibbs free energy demonstrated the effect of the defect passivation by parylene films. Finally, the parylene-passivated QD-based photosensor was applied to the detection of two kinds of food-poisoning and gastroduodenal disease bacteria (Listeria monocytogenes and Helicobacter pylori).

First-principles study on the adsorption of divalent heavy metal ions by black phosphorus in water

With the rapid development of electronics, the application and research of two-dimensional materials have been at the forefront of the world’s scientific research. Black phosphorus (BP) has the advantages of large specific surface area, anisotropy, band tunability, high electrical conductivity and high theoretical specific capacity, which make it very promising for research in the fields of medicine, aerospace and electrochemistry. This paper calculates the electronic structure and adsorption properties of BP in water for different heavy metal ions of Pb[Formula: see text], Hg[Formula: see text] and Cd[Formula: see text], including adsorption energy, bandgap, electron density and Mulliken population analysis, based on the first-principles approach of density generalized theory. First principles are quantum mechanical calculations based on density functional theory (DFT), which is a dominant well-developed method in the field of materials simulations, with low errors and high efficiency, especially in systems containing metallic particles. The results showed that the Pb[Formula: see text] adsorption system in water was more stable than the Hg[Formula: see text] adsorption system and the Cd[Formula: see text] adsorption system. The bandgap values of 0.617, 0.785 and 0.715[Formula: see text]eV of BP after adsorption of Pb[Formula: see text], Hg[Formula: see text] and Cd[Formula: see text] in water are smaller compared to 0.891[Formula: see text]eV of intrinsic BP, and its properties change from direct bandgap semiconductor to indirect bandgap semiconductor. The higher the stability of a system for the adsorption of different heavy metal ions by BP, the higher the internal electron activity of the adsorption system and the amount of electron transfer. Meanwhile, it is concluded that the electrons mainly transfer from P to heavy metal ions in all the adsorption systems. The electron transfer of the BP-Pb[Formula: see text], Hg[Formula: see text], and Cd[Formula: see text] adsorption system occurs mainly in the p, s, and s/p orbitals, respectively. The above content investigated the electronic structure changes and internal electron transfer of heavy metal ions adsorbed by black phosphorus in water, expecting to provide a new reference basis for the detection of heavy metal ions in industrial wastewater using black phosphorus.

INVESTIGATING MAGNETIC, DIELECTRIC, OPTIC AND MORPHOLOGIC PROPERTIES OF NANO-NICKEL OXIDE-DOPED NdFeO3

In this investigation, [Formula: see text]-Fe2O3 was prepared via co-precipitation and nano-NiO and NdFeO3 were synthesized using the sol–gel method. For NdFe[Formula: see text]Ni[Formula: see text]O3 synthesis, Nd2O3, [Formula: see text]-Fe2O3, and nano-NiO compounds were mixed via the solid state method. The effect of each component and that of nano-NiO on the NdFe[Formula: see text]Ni[Formula: see text]O3 crystal properties was characterized by using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), ultraviolet-visible (UV–Vis), vibrating sample magnetometer (VSM), impedance and bandgap analyses. The orthorhombic perovskite structure was confirmed by the XRD data. With the doping of nano-NiO, the unit cell volume was found to decrease. The UV–Vis spectroscopy showed that the nano-NiO-doped optical bandgap ([Formula: see text]) had increased. The VSM analysis demonstrated that by doping nano-NiO to weak ferromagnetic NdFeO3, the resulting NdFe[Formula: see text]Ni[Formula: see text]O3 was rendered superparamagnetic. The real and imaginary parts of dielectric permittivity ([Formula: see text]′ and [Formula: see text]″) and the loss tangent (tan[Formula: see text]) characteristic of the compounds were measured at AC-signaled frequencies of 100 Hz–10 MHz and a voltage range of 0–20 V DC. The increase in active charge transmission with the doping of nano-NiO reduced the [Formula: see text]′ values. In addition, the large differences between the [Formula: see text]′ values were thought to be caused by the breakdown voltage ([Formula: see text]) effect of the compounds. The [Formula: see text]″ and tan[Formula: see text] changes revealed the dipole formation of the compounds at different voltages, their relaxation regions and their polarization mechanism type. The dielectric loss behavior of the compounds demonstrated their good dielectric material properties. This study investigated the effect of method difference and doped material particle size on magnetic and dielectric properties.

Vibration and bandgap characteristics analysis of multiple beams with arbitrary connection angles

Multi-coupled beam structures can be encountered in a wide range of engineering disciplines. Due to the possible periodicity of structures, it is important to investigate their vibration and bandgap characteristics. In this study, an accurate wave-based analytical model for the in-plane vibration of a multi-coupled beam structure with arbitrary coupling angles is developed. The reflection and transmission matrices corresponding to the incident waves arriving at the angular junctions from different directions are derived. By combining these reflection and transmission matrices, the free and forced vibrations of the multi-coupled angle beam structures can be analyzed systematically and concisely. The theoretical analysis results are in good agreement with those calculated from the FEM analysis results, which verifies the accuracy of the current method. Moreover, the analytical expression of the bandgap characteristics of infinite multi-coupled beam structures is formulated. The bandgap characteristics results of the infinite multi-coupled beam structures coincide well with the frequency response function (FRF) of the finite multi-coupled beam structures, which verifies the correctness of the analytical expression of bandgap analysis. Further results show that a low-frequency and wide bandgap can be obtained by choosing the appropriate lattice constants and junction angles, which has positive significance for the efficient design and vibration attenuation of multi-coupled beam structures in practical engineering.

Iron and vanadium co-doped WO3 nanomaterial and their composites for waste water applications

Tungsten oxide (WO3), Iron and vanadium co-doped tungsten oxide (FeVWO3), and the composite of iron and vanadium co-doped tungsten oxide with graphitic carbon nitride (FeVWO3@g-C3N4) were prepared for the photocatalytic study. WO3 and FeVWO3 were synthesized by co-precipitation, and the composite FeVWO3@g-C3N4 was synthesized by an ultra-sonication approach. All the prepared materials were analyzed by different techniques. Structural study was done by XRD, functional group analysis by FTIR, and SEM was used for the morphological study of the nanoparticles. EIS measurements were done to investigate the electrical properties of fabricated materials. Photocatalysis was performed for the band gap analysis. Pendimethalin (PM) a herbicide and aspirin (pharmaceutical product) were used in photocatalysis and degraded by the prepared photocatalysts (WO3, FeVWO3, and FeVWO3@g-C3N4). WO3 and FeVWO3 have 2.62 eV and 2.34 eV Eg values of band gap, respectively. FeVWO3 has a lower Eg value than WO3. The decrease is due to the doping, and generation of further energy levels in the band gap of the pure sample, and these energy levels cause changes in the electronic structure of the sample. The composite shows a high degradation efficiency. The percentage degradation of pendimethalin and aspirin by FeVWO3@g-C3N4 was 82.26 % and 92.84 %. It is because of the presence of g-C3N4 which provides greater surface area for better degradation efficiency.