Structure Properties Of Materials Research Articles

Investigation on structural failure criteria and material property uncertainties of prestressed concrete containment structure

This study is to examine load-carrying capacity of a prestressed concrete containment vessel under the structural failure mode test via non-linear finite element (FE) analyses. Firstly, suitability of three candidate structural failure criteria was evaluated at ambient temperature condition, of which results showed that the maximum principal strain-based one predicts ultimate pressure capacity (UPC) most closely with the test data. Effect of increasing temperature corresponding to a postulated severe accident-induced condition was investigated and the UPC exhibited reduction ratios of 1.19–1.49% at the peak temperature of 200 °C approximately depending on each failure criterion. Finally, parametric FE analyses at 95% confidence level were performed to quantify effect of material property uncertainties. Overall, the impact of altered material properties of concrete and rebar was higher than that of tendon prestress, and the increase of UPC in upper bound cases exceeded the decrease of UPC in lower bound cases.

Structural phase transition and optical properties of zero-dimensional cobalt bromide hybrid material

Zero-Dimensional (0D) metal halide materials have recently emerged as a class of potential optoelectronic materials because of the structural diversity and superior photophysical properties. Here we report a 0D cobalt bromide hybrid material, [Br(CH2)3NH3]2CoBr4 (BPA-CoBr4, BPA=Br(CH2)3NH3, 3-Bromopropylamine), in which the isolated metal halide tetrahedron (CoBr42-) is completely separated each other and surrounded by the organic ligand Br(CH2)3NH3+. Differential scanning calorimetry (DSC) measurements exhibit BPA-CoBr4 undergoes a first-order structural phase transition, as clearly visible to a pair of weak peaks at 340 K (heating) and 317 K (cooling). Single crystal X-ray diffractions were carried out at 293 K and 360 K to explain the phase transformation mechanism, indicating it is an isostructural order–disorder type. The crystal structures which both crystalize in a monoclinic P21/c crystal symmetry and the most distinct difference between room-temperature and high-temperature structures is the order–disorder transition of the 3-Bromopropylamine, which is the driving force of the phase transition. The UV–vis absorption spectra reveal that BPA-CoBr4 has a steep absorption edge at 280 nm corresponding to photo energy of 4.4 eV. The density functional theory (DFT) calculations were performed to study the electronic structure with narrower indirect bandgap 3.9 eV which is lower than the experimental values. PDOS plots show that the electronic states of Co-d and Br-p orbitals are mainly contributed for the VBM and CBM of BPA-CoBr4.

Effects of structure parameter and material property on thermal performance of on-board hydrogen storage tanks during fast refueling

As a power generation fuel, high-pressure hydrogen gas is widely used in transportation, and significantly contributed to development of hydrogen fuel cell electric vehicles. However, obvious temperature rise generated during fast refueling causes serious safety risk to reliable operation of fuel cell stacks. Therefore, it is necessary to conduct in-depth research on fast filling process. Based on safety reasons, the SAE J2601/ISO 15869 strictly regulates the maximum temperature limit of 85 °C in specifications for refueling hydrogen gas tanks. In this study, a 70 MPa, Type IV on-board hydrogen storage tank is adopted as the research object, and a 2-dimensional axisymmetric numerical model is established to study the temperature rise of the vapor within storage tanks during fast refueling. The Realizable k-ε turbulence model is employed to simulate high intensity turbulent fluctuation during fast filling. Considering the compressibility of vapor, the state of equation for real hydrogen gas is used by obtaining fluid thermodynamic properties from the National Institute of Standards and Technology database. Three groups of fast filling experiments are selected to validate the developed numerical model. The comparison result shows that the numerical model has good prediction ability on hydrogen fast refueling. The final mass average temperature differences between numerical results and experimental data are 2.6 K, 4.3 K, and 0.03 K, respectively. Based on the developed numerical model, the influences of structure parameters and material properties on the temperature rise of hydrogen storage tanks are investigated. The results indicate that the inlet diameter and wall thickness of the inner and outer layers of the storage tank have weaken impacts on the temperature rise during rapid charging, with the maximum temperature differences of 1.8 K, 0.74 K, and 0.54 K, respectively. Due to the influence of heat capacity, the material properties of different layers exhibit a similar variation trend. This work can deepen researchers' understanding of the temperature rise of on-board hydrogen storage tanks during fast filling, and provide technical references for the structural optimal design of tanks and rapid refueling at hydrogen stations.

Correlation of heat transport mechanism and structural properties of GaN high electron mobility transistors

Grain sizes, impurities, and layer thicknesses in the nm-range affect the heat transport and, hence, hinder proper heat dissipation of GaN-based devices. To obtain a clear picture of heat dissipation, the mechanisms of heat transport must be linked to the structural properties of the nitride-based materials in the device. In this paper, a systematic investigation of the typical layers of GaN high-electron mobility transistor stacks was conducted by time-domain thermoreflectance analysis and Raman measurements. The analyzed layers are the AlN nucleation layer, the Al0.3Ga0.7N transition layer, the AlGaN/AlN superlattice, the C-doped GaN back-barrier, and the uid GaN layer. The results were interpreted using the Born–van Karman model, including the suppression function approach to describe the governing heat transport mechanisms. Investigation of this AlN nucleation layer showed that its phonon scattering is dominated by impurity and grain boundary scattering. The Al0.3Ga0.7N transition layer was shown to have a reduced thermal conductivity not only due to alloy scattering but also because of grain boundary scattering. The AlGaN/AlN superlattice showed a thermal conductivity lower than the Al0.3Ga0.7N transition layer, especially at higher temperatures (7.2 ± 0.2 W/mK vs 14.1 ± 0.4 W/mK at 300 °C). Caused by the enhanced AlGaN/AlN interface density, the thermal conductance was found to be 2 GW/m2 K. The AlGaN/AlN superlattice indicated an anisotropic thermal transport with a factor of ∼1.5. The C-doped GaN layers were analyzed in terms of their size-dictated thermal conductivity, resulting in a reduction of ∼66% from 1 μm to 250 nm at 30 °C. Raman spectroscopy revealed that the thicker the GaN layer, the higher the compressive stress in GaN, which additionally results in a higher thermal transport. The investigations of the heat transport depending on the structural properties enabled an accurate determination of the thermal conductivity of the layer stack. These thermal conductivities served as input parameters for 3D simulation to extract the temperature, in terms of the thermal resistance, of such high-electron mobility transistor stacks. This simulation shows the importance of the GaN layer in terms of thermal management. This work uncovers the thermal transport in GaN-based transistor stacks with the aim to improving the thermal design.

Circular Economy of Construction and Demolition Waste for Nanocomposite Cement: XRD, NMR, Vickers, Voltammetric and EIS Characterization.

In this paper, we present the structural, mechanical and electrical properties of composite cement materials that can be widely used as substituent for cement. We start with the characterization of a composite cement sample using an analysis of X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) spectra. The measurements of the Vickers hardness, cyclic and sweep linear voltammetry and electrochemical impedance spectroscopy (EIS) of composite cement materials were also recorded. This study compared the effect of the different nanocomposites added to cement on the mitigation of the alkali-silica reaction, which is responsible for the swelling, cracking and deleterious behavior of the material. The enhancement in Vickers hardness was more pronounced for composite cement materials. In contrast, the values of Vickers hardness decreased for the composite cement containing mortar and the control sample, suggesting that the long-term performance of cement was compromised. In order to obtain information about the bulk resistance of the composite cement material, electrochemical impedance spectroscopy (EIS) data were employed. The results suggest that for composite cement materials, there is an improvement in bulk electrical resistance, which can be attributed to the lower amounts of cracks and swelling due to lower expansion. In the control sample, a reduction in the bulk resistance suggests the formation of microcracks, which cause the aging and degradation of the material. The intersection of arcs in the EIS spectrum of the mixed composite cement sample gradually increased by an alkaline exposure of up to 21 days and finally shifted towards a low value of high frequency with an increase in alkaline exposure of up to 28 days.

Exploring the structural, electronic, and optical properties of novel two-dimensional ABX-type materials

A first-principles study of the structural, electrical, and optical properties of graphene-like two-dimensional (2D) materials ABX (A=Na/K, B=C/Si/Ge, and X=N/P/As) such as NaCN, KCN, NaCP, KCP, etc was undertaken using state-of-the-art Density Functional Theory (DFT). The investigation encompasses essential parameters such as structural stability through ab initio molecular dynamics (AIMD), electronic structure, and dielectric constants. The AIMD measurements reveal that the structures stay stable for up to 10 picoseconds (ps). Band structure calculations at the PBE level of theory revealed that most materials are semi-conducting with a band gap of 1-3 eV, except NaCN and KCN, which exhibited insulating behaviour. Using hybrid functional (HSE), only eight materials were identified to have a band gap in the visible range. Optical properties have also been investigated to understand their interaction with light. Peaks in the imaginary component of the dielectric function were attributed to inter-band transitions. Several materials were discovered to be optimal for photo-catalysis, while six were found to exhibit conductivity of the order of ∼1012 (Ω−1cm−1s−1) at room temperature.

Study of structural and magnetic properties of laser-irradiated zinc ferrite material

Crystalline ZnFe2O4 (zinc ferrite) material was prepared using the sol–gel technique and converted in the forms of 3 pellets, out of which 2 pellets were irradiated at room temperature by pulsed Nd:YAG laser with 1.5 W, λ = 532 nm named ZF1 and continuous AlGaAs diode laser of 4 W, λ = 808 nm called ZF2, respectively, while the 3rd pellet was kept as control and named ZF. Synchrotron X-ray Diffraction (S-XRD) reveals the marginal variation in the structure having the lattice parameters of 8.4364 Å for ZF, 8.4176 Å for ZF1 and 8.4187 Å for ZF2. The porosity after laser irradiation has been increased to 10.87% for ZF1 and 10.84%, for ZF2 from 10.28% for ZF. The blocking temperature (TB) has been ∼15 K for all samples. There had been a slight variation in the magnetization of irradiated pellets at 5 and 300 K compared to ZF. The separation between ZFC and FC curves, the measure of interaction between Fe ions has increased for irradiated pellets when compared with the separation for ZF. Moreover, magnetization (M) versus applied magnetic field (H) at 5 K in the range of ±1 T shows the ferrimagnetic behaviour and this ordering has been seen up to TB as visible from M-T curves, whereas the material becomes superparamagnetic above TB as observed from M-T & M-H measurements.

Modification of epoxy-novolac compositions using glass microspheres and study of the properties of materials based on them

The physicomechanical, morphological and operational properties of polymer structural materials based on epoxy-novolac oligomers filled with glass microspheres are considered. The possibility of regulating the density of spheroplastics by varying the number and sizes of glass spheres while maintaining good physical and mechanical properties of the materials has been studied.

Development of modifying additives for epoxy oligomers based on household waste polyethylene terephtalate

A method for synthesis of oligoester polyols (OEP) and modified resins is presented, the effect of the OEP content on the dynamic viscosity, reactivity of resins, physicochemical and mechanical properties of structural materials is studied. Materials based on epoxy-diane resin modified with glycolyzed products were obtained. It was found that the use of the developed oligomers with optimal content of epoxy-diane resin as modifier leads to an increase in some characteristics of the resulting materials: elasticity, tensile strength and elastic modulus at static bending, viability of the composition. The use of glycolysis products is advisable because it is a promising method for recycling of household waste polyethylene terephthalate. It is characterized by ease of synthesis, as well as low cost and availability of initial components, and makes it possible to increase the physical and mechanical properties of structural materials based on epoxy resins, as well as contribute to solving environmental problems.

Indium-doped tungsten oxide architectures anchored on 2D rGO Matrix with enhanced visible-light-response and efficient charge separation for photocatalytic degradation of organic pollutants

Visible-light-responsive photocatalysis has been recognized as a sustainable strategy to address environmental pollution, but semiconductor-based photocatalysts often suffer from many shortcomings, including low visible light absorption and rapid recombination of photo-generated charge carriers. In this regard, rationally designed composite materials have gained substantial prominence, as achieving an ideal photocatalyst's characteristics in a single component material is frequently difficult. In the present study, we have synthesized pure (WO3) and indium-doped tungsten oxide (In-WO3) by the facile solvothermal route. The doped material was anchored on a 2D rGO matrix to fabricate the In-WO3/rGO composite. The structural, morphological, electrical, and optical properties of the as-synthesized materials were investigated as a function of doping and composite fabrication by various physical and electrochemical techniques. The comparative photocatalytic performance was evaluated by degrading Congo Red (CR) dye and paracetamol (PCM) drug. The composite material shows degradation efficiencies of ∼96 % (K=0.0174 min−1) and ∼91 % (K=0.0144 min−1) for CR dye and PCM drug, respectively. The boosted catalytic performance corresponds to the declined band gap (2.53 eV) and increased conductivity (0.1270 Sm−1), which enhances its visible light absorption and a surge in the charge carrier's population. The kinetics, relative contribution of different active species generated, and the potential mechanism of photodegradation reaction are discussed in detail. The significant increase in photocatalytic performance of the fabricated In-WO3/rGO composite discloses its promising catalytic potential for the degradation of recalcitrant organic pollutants.

Pressure-induced metallization in Pb3Mn7O15

The multiferroic material Pb3Mn7O15 exhibits a high resistivity arising from the orbital electrons localized around the manganese ions, which hinders its potential applications. Previous studies indicated that the resistivity of Pb3Mn7O15 was influenced by its crystal structure and the distribution of Mn ions. Consequently, pressure-induced structural change are expected to represent a viable method for tuning the resistivity and other properties of this compound. In the present study, the pressure effect on the resistivity of Pb3Mn7O15 was investigated up to 42 GPa. Furthermore, the X-ray diffraction and Raman spectroscopy techniques, along with the density functional theory calculations were employed to study the crystal structure evolution of Pb3Mn7O15 under pressure. The results demonstrate an electronic semiconductor-metal phase transition in Pb3Mn7O15, accompanying an irreversible orthorhombic to monoclinic phase transition. Additionally, within the orthorhombic phase, an iso-structural phase transition is observed, originating from the magnetic moments collapse of manganese cations. This study provides compelling evidence that high-pressure processing can be employed to modulate the crystal structure and functional properties of multifunctional materials.

High‐fidelity digital twins: Detecting and localizing weaknesses in structures

AbstractAn adjoint‐based procedure to determine weaknesses, or, more generally, the material properties of structures is developed and tested. Given a series of load cases and corresponding displacement/strain measurements, the material properties are obtained by minimizing the weighted differences between the measured and computed values. The present paper proposes and tests techniques to minimize the number of load cases and sensors. Several examples show the viability, accuracy and efficiency of the proposed methodology and its potential use for high fidelity digital twins.

Preparation, electronic structure and thermal properties of Zn-doped LaMgAl11O19 materials

LaMgAl11O19 (LMA) with magnetoplumbite structure is a promising thermal barrier material due to its excellent thermal properties. In this work, Zn-doped LMA materials were studied in order to improve the thermal performance, and LaZnxMg1-xAl11O19 (x = 0, 0.1, 0.3, 0.5, 0.7, 1.0) were prepared by sol-gel method. The as-synthesized powder materials possess pure LMA phase and show the morphology of hexagonal plates. X-ray photoelectron spectroscopy result shows that there are AlO4 tetrahedra and AlO6 octahedra units in the target materials, and Zn2+ ions replace Mg2+ ions to occupy the tetrahedral position of magnetoplumbite structure. The composition LaZn0.3Mg0.7Al11O19 material exhibits the lowest thermal conductivity of 0.38 W/(m·K) at 1000oC while maintaining a high coefficient of thermal expansion (10.86 × 10−6 K−1). Therefore, the thermal properties of LMA materials can be improved by adding an appropriate amount of Zn ions.

Analysis of the Impact of Waste Fly Ash on Changes in the Structure and Thermal Properties of the Produced Recycled Materials Based on Polyethylene.

This paper presents the results of the research on the structure and thermal properties of materials made from fly ash based on high-density polyethylene (HDPE). Composites based on a polyethylene matrix with 5, 10, and 15 wt% fly ash from hard coal combustion content were examined. Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) was used to identify characteristic functional groups present in the chemical structure of polyethylene and the composites based on its matrix. Structural analysis was performed using X-ray diffraction (XRD), a differential scanning calorimeter (DSC), and microscopic examinations. Mechanical properties were also examined. Analysis of the thermal effect values determined by the DSC technique, XRD, and FTIR-ATR allowed the evaluation of the crystallinity of the tested materials. Polyethylene is generally considered to be a two-phase system consisting of crystalline and amorphous regions and is a plastic characterized by a significant crystalline phase content. Based on the FTIR-ATR spectra, DSC curves, and XRD, the effect of the filler and the changes occurring in the materials studied resulted in a decrease in the degree of crystallinity and a change in the melting point and crystallization temperature of the polymer matrix were established. Microscopic examinations were carried out to analyze the microstructure of the composites to collect information on the distribution and shape of the filler particles, indicating their size and distribution in the polymer matrix. Furthermore, the use of scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS) allowed for the microanalysis of the chemical composition of the filler particles.

Investigation of structural, dielectric and electrical properties of lead-free bismuth-based layered multifunctional material: CaBiGdNbVO9 for device fabrication

Investigation of structural, dielectric and electrical properties of lead-free bismuth-based layered multifunctional material: CaBiGdNbVO9 for device fabrication

Topological hydrogen-bonded organic frameworks (HOFs) and their electronic applications in sensor, memristor, and neuromorphic computing

Recently, an emerging class of hydrogen-bonded organic frameworks (HOFs) has become an appealing member of organic material family, attributed to their layered self-assembly structures, high-crystalline, and environmentally friendly characteristics, which have rapidly propelled their development in the field of electronic devices. In this context, we focus on the latest category of topological HOFs, with particular attention given to cutting-edge experimental demonstrations, exceptional electrical performances, and promising applications. First, a concise concept and fundamental mechanism of HOFs are provided, elucidating the potential correlation between structural designs and material properties. Subsequently, a comprehensive summary is presented on the preparation and synthesis methods, such as hydrothermal techniques, epitaxial growth, electro-deposition, among others. Notably, the latest advancements in HOFs-based electronics are thoroughly introduced and discussed, along with their applications in sensors, memristors, artificial synapses, neuromorphic computing, and human perception systems. Finally, the future challenges and prospects of topological HOFs are elaborated upon with the aim of providing valuable guidance for high-performance HOF-based electronics.

Unraveling the Solvent Regulation in the Heteroatom-Doped Endohedral Gold Clusters: A Theoretical Study on the Electronic Properties and O2 Activation.

Liquid-phase synthesis of atomically precise nanoclusters has experienced rapid development recently, where polar solvents are indispensable in such a process. However, the regulation effect of solvents on the structural and electronic properties of different metal clusters and cluster assembly materials is still not well understood. Herein, a comprehensive density functional theory calculation has been performed to explore the solvation effect on heteroatom-doped endohedral gold clusters that always have remarkable stabilities and tunable electronic structures. The solvation free energy of the M@Au12 clusters (M = Cr, Mo, W, Co, Rh, Ir, Cu, Ag, and Au) was found to be related to the charge distribution of the central doped-atom M and the outer Au12 cage. Moreover, the aqueous solvent was observed to be able to increase the adsorption capacity of M@Au12 to O2 following the activation of O2 through the charge transfer from M@Au12 to O2, in which the transferred electrons occupy the π antibonding orbital of O2. In addition, the water solvent can also improve the hydrogenation reaction of O2 to form OOH over M@Au12, where the activation energy barrier for this process is very low with the participation of the solvent. Considering the importance of solvents in the liquid-phase synthesis of atomically precise clusters, these findings highlighted here could provide valuable theoretical guidance in potential applications of functional gold nanoclusters, especially in the liquid-phase cluster catalysis.

Distributed-collaborative surrogate modeling approach for creep-fatigue reliability assessment of turbine blades considering multi-source uncertainty

This paper proposes a substructure-based distributed-collaborative surrogate modeling approach for improving the accuracy and efficiency in the estimation of the creep-fatigue reliability of gas turbine blades with the integration of the Least Absolute Shrinkage and Selection Operator (LASSO), kriging, Distributed Collaborative (DC) strategy and substructure simulation method, called as the substructure-based DCLKM. Further, the creep-fatigue reliability assessment framework is set by combining the proposed substructure-based DCLKM with some theoretical models, which takes into account the uncertainties of structural sizes, applied loads and material properties and the nonlinearity of creep/fatigue damage interaction. Firstly, the total strain range, mean stress, absolute temperature and maximum stress at the critical location are regarded as the first-level output responses, and their required samples are predicted through the fitted surrogate models. Secondly, the creep life and Low-Cycle Fatigue (LCF) life are regarded as the second-level output responses and predicted. Finally, the creep-fatigue damage and reliability assessment are performed for several given applied cycles, respectively. The proposed substructure-based DCLKM is validated on a case study. The results show that the proposed substructure-based DCLKM is feasible with high accuracy and efficiency in the creep-fatigue reliability assessment of turbine blades.

Electronic structure, optical properties, and thermoelectric properties of Mg-doped GaN materials

This work was based on first principles calculations and investigated the electronic structure, optical properties, and thermoelectric properties of Mg doped GaN bulk materials. It analyzed the effect of Mg impurities defects on the properties of GaN bulk materials. Mg doping can transform GaN materials into p-type semiconductors, which is crucial for achieving p-n junctions or p-type layers in GaN based electronic devices. The calculation results showed that MgN-GaN and MgInterstitial-GaN(MgI-GaN) belong to n-type doping, while MgGa-GaN belongs to p-type doping. In addition, the optical properties and thermoelectric properties of different GaN doping models were calculated. It was found that the maximum ZT values of the MgN-GaN, MgGa-GaN, MgI-GaN doping models reached 4.46, 5.09 and 5.35, respectively. The Mg impurities can help improve the ZT value of semiconductors compared to intrinsic GaN material. This research result has significance for the application of GaN based semiconductor materials in thermoelectric fields.

Production of low-cost lactic acid from dairy wastes and dates wastewater and bioactive silver-poly (lactic acid) nanocomposite for biological applications

L-Lactic acid-producing Lactobacillus lactis and L. plantarum were isolated from date wastes. The fermentation process was optimized using a one-variable-at-a-time approach. Dairy wastewater and wastewater from the date industry were utilized as low-cost culture media to produce lactic acid. The selected two bacterial strains were co-cultured in wastewater medium to produce L-lactic acid and D-lactic acid. Lactic acid production was significantly improved by glucose (carbon source), yeast extract (nitrogen source), initial inoculum level, and polysorbate 80. A central composite design and response surface methodology were used to optimize the variables and their levels to improve lactic acid yield. The supplemented yeast extract, glucose, and polysorbate 80 improved lactic acid. The predicted variables and their levels for maximum lactic acid production were glucose (67.5 g/L), yeast extract (10.28 g/L), and polysorbate 80 (0.48 mL/L). The prepared nanocomposites exhibited antibacterial activity against foodborne bacterial pathogens. The structural properties of the silver-polylactic acid nano compost materials were determined. The characterized compost materials exhibited a peak absorption wavelength of 430 nm. The silver and poly(lactic acid) were characterized using X-ray diffraction analysis and were 30 to 50 nm in size.