Crystal Method Research Articles

Crystal Plasticity Finite Element Simulation of Grain Evolution Behavior in Aluminum Alloy Rolling.

In this study, the crystal plasticity finite element method was established by coupling the crystal plasticity and finite element method (FEM). The effect of rolling deformation and slip system of polycrystalline Al-Mg-Si aluminum alloy was investigated. The results showed that there was a pronounced heterogeneity in the stress and strain distribution of the material during cold rolling. The maximum strain and shear strain occurred at surface of the material. The smaller the grain size, the lower the strain concentration at the grain boundary. Meanwhile, a smaller strain difference existed between the grain interior and near the boundary. The rotation of grains leads to significant differences in deformation and rotation depending on their initial orientations during the rolling process. The slip system of (11-1)<-110> had a large effect on the plastic deformation, (111)<10-1> is second, and the effect of (1-11)<011> slip system on the plastic deformation is the smallest. After deformation, the grain orientation concentration was increased with deformation. Therefore, both the strength and volume fraction of texture were increased with the increase in rolling deformation. The experimental results of EBSD indicated that the large rolling reduction resulted in severe grain twisting, so the texture strength was increased. The simulation results were in close agreement with the experimental results. This study provides a theoretical basis for the rolling process, microstructure, and performance control of aluminum alloys.

Mechanical Design Guidelines to Inhibit Fracture in Perovskite Solar Cells

Perovskite (PVSK) solar cells offer significant benefits over conventional silicon cells including low‐cost solution processibility, minimal materials usage related to strong photon absorption in thin‐film cell architectures, and a tunable bandgap. However, PVSK films are mechanically fragile, and fracture of PVSK layers and adjacent interfaces are a significant concern during fabrication, encapsulation, and operation. Herein, a thin‐film mechanics fracture analysis tailored for p–i–n and n–i–p PVSK solar cells on both soda lime glass and polyimide substrates fabricated with three PVSK crystallization methods is presented. The role of thermal processing of each cell layer is explored to determine the maximum allowable temperature below which fracture is inhibited. In the analysis, the mechanics basis for processing and materials selection guidelines for preventing fracture in PVSK solar cells is provided.

Physicochemical Methods for the Structuring and Assembly of MOF Crystals.

ConspectusMetal-organic frameworks (MOFs) are promising for various applications through the creation of innovative materials and assemblies. This potential stems from their modular nature, as diverse metal ions and organic linkers can be combined to produce MOFs with unique chemical properties and lattice structures. Following extensive research on the design and postsynthetic chemical modification of MOF lattices at the molecular level, increasing attention is now focused on the next hierarchical level: controlling the morphology of MOF crystals and their subsequent assembly and positioning to create functional composites.Beyond well-established methods to regulate crystal size and shape through nucleation and coordination modulation, physicochemical techniques leveraging wetting effects, interparticle interactions, and magnetic or electric fields offer attractive avenues for the hierarchical structuring and assembly of MOFs. These techniques facilitate crystal alignment and yield unique superstructures. While our research group primarily focuses on directing MOF crystal orientation and positioning using external stimuli such as magnetic and electric fields, we also explore hierarchical MOF synthesis and structuring using liquid interfaces and depletion force-assisted packing.This account highlights our journey and progress in developing methods to regulate the morphology, assembly, orientation, and positioning of MOF crystals, placed in the context of work by other groups. First, we examine commonly utilized structuring methods for MOF crystals that employ liquid-liquid and air-liquid interfaces to spatially confine reactions, allowing us to access unique morphologies such as mushroom-like crystals and Janus particles. We also discuss strategies for concentrating and packing MOF crystals into superstructures, utilizing fluid interfaces for spatial confinement of crystals, depletion forces, entropic effects, and crystal sedimentation.A particularly compelling challenge in expanding the applicability of MOF materials is how to manipulate free-standing MOF crystals. This issue is especially important because MOFs are typically produced as loose powders, and industrial material processing is generally more efficient when the material is fluidized. While extensive research has been conducted regarding MOF growth on substrates with both positional and orientational control, there is a clear need for similar precision with free-standing MOFs dispersed in a fluid matrix. Our group has thus focused on the relatively new, yet powerful approach of using electric and magnetic fields to manipulate MOF crystals, which offers unprecedented control over the orientation and positioning of dispersed MOF crystals, complementing the more well-established methods of MOF growth on substrates. In this Account, we provide foundational background and discussions on the interactions between these external fields and MOF crystals, including critical considerations for effective MOF manipulation using such techniques. We also discuss their unique advantages and applications, and briefly examine potential application areas, such as photonics, smart materials like soft robotics and absorbents, and sensing. This Account highlights the promising potential of well-organized and aligned MOF crystals over randomly oriented ones in various applications, owing to enhanced selectivity and performance. It underscores the importance of specialized assembly methods to advance materials science and engineering, encouraging the reader to explore such approaches.

Investigation on high temperature fatigue-oxidation behavior of Ni-based single crystal with film cooling holes considering arrangement effect

The fatigue-oxidation behavior of Ni-based single crystal with film cooling holes (FCHs) fabricated by femtosecond laser was investigated considering arrangement effect. Low cycle fatigue tests were conducted under 900 °C/713 MPa and 1000 °C/500 MPa. The experimental results show that fatigue lifetime reduced as the temperature increased at equal proportional stress. And, the specimens with square penetration pattern have an average fatigue life that is higher than the specimens with triangle penetration pattern at the same condition. Then, the crack propagation modes are characterized on the fracture path, and the fatigue failure mechanism is revealed by analyzing the fracture morphology. The microstructure evolution around the FCHs shows that the fatigue crack nucleation is caused by the coupling effect of fatigue and oxidation. According to the damage mechanism, a new fatigue-oxidation coupling damage model is proposed based on crystal plastic theory. The calculation results using crystal plasticity finite element method (CPFEM) considering coupling damage show that the maximum resolved shear stress (RSS) of the FCHs triangular arrangement is higher than that of quadrilateral arrangement at the same condition. Finally, fatigue life is predicted based on coupling damage accumulation, and the results show that the accuracy of life prediction is within 2 times data dispersion band.

A review of high-entropy ceramics preparation methods, properties in different application fields and their regulation methods

High-entropy alloys (HEAs) provides a new way to develop new materials with adjustable performance due to their unique cocktail effect. Inspired by HEAs, a ceramic material with high-entropy effect has been developed, which was named high-entropy ceramics (HECs). With the introduction of the concept of entropy stability, research on HECs has developed rapidly. At present, research on the performance of HECs has extended to traditional performance such as thermomechanical performance, oxidation resistance, and magnetic properties, as well as emerging performance such as catalytic performance, optical properties, and radiation resistance. Based on the definition of HECs, this paper reviews the crystal structure and preparation methods of HECs and supplements the simulation calculation methods and descriptors which is suitable for HECs. In this paper, the performance of HECs at this stage is divided into traditional fields and emerging fields according to the application fields. A variety of performance regulation methods are reviewed, and the development and research directions of HECs are prospected.

Evaluation of Experimental and Economic Potential of Industrial Borax Aqueous Solution by Eutectic Freeze Crystallization Method

Evaluation of Experimental and Economic Potential of Industrial Borax Aqueous Solution by Eutectic Freeze Crystallization Method

Mass transfer and formation of micro-inclusions in Ti-sapphire grown by the HDC method

The formation mechanism of micro-inclusions in titanium-sapphire crystals grown with the method of horizontal directional crystallization in a gas atmosphere was studied. It has been shown that the micro-inclusions of metallic tungsten and/or molybdenum are mainly formed at the surface of the unmelted charge. The thermodynamic analysis of the possible reactions of Mo and W among the charge components, the products of charge dissociation, and the components of the technological atmosphere was carried out. It is shown that CO2, CO, H2O, as well as suboxides of Al and Ti, can serve both as oxidizers of Mo and W and as reducing agents of their condensed oxides. The mechanism of mass transfer within which gaseous Mo and W oxides are reduced on the charge surface to form metal micro-particles was proposed. These particles further fall into the melt and then are transported with convective flows to the crystallization front and embedded into the crystal as micro-inclusions.

Dynamic interaction of heavy metals and mineralogical shifts in stream sediments exposed to MSW landfill leachate in a semi-arid basaltic terrain

Investigating concentrations and spatial patterns of physicochemical parameters in landfill leachate and their profound impacts on stream sediments is an important issue for environmental sustainability. Therefore, the present study showed that the specifics landfill leachate and its interactions with stream sediments within the unique geological context of semi-arid basaltic terrain of the Deccan Volcanic Province in Pune, India. Employing advanced geo-accumulation indices and crystal phase differentiation methods, the study unveils the intricate metamorphosis of heavy metals and mineralogical composition, tracing the transformative journey from leachate to sediments. Noteworthy revelations emerge, particularly in the striking associations between heavy metals and the mineralogical composition, which encompasses primary and secondary minerals (calcite, quartz, and Fe–Mg oxides). These findings underscore the acceleration of weathering processes within this distinctive geological milieu. The 'geo-accumulation index' exhibits pronounced elevations in proximity to the landfill site, with persistence downstream, reliant upon the evolving weathering and accumulation dynamics. The lower reaches of the study area have higher concentrations of various heavy metals (Fe, Mn, Zn, Cr, Cu, Ni, Co, Hg, As, and Cd). These heavy metals are primarily sequestered within silt-dominated sediments conquered by augite, olivine and plagioclase minerals. Present research reveals the complex interplay between heavy metals in leachate and their physical and chemical interactions with sedimentary materials. These gradational shifts in mineralogy and geochemistry serve as compelling evidence of the transformative impact of leachate discharge within the distinctive basaltic geological framework. This study offers valuable insights into the complex environmental processes occurring at the intersection of landfill leachate and natural geological formations, enhancing the understanding of the dynamic geochemical interactions that shape this semi-arid basaltic terrain.

Flexible plasmonic display featuring differentiated and localized control over transmission and reflection

Structural colors using metal materials, plasmonic color generation, can confine optical excitation beyond the diffraction limit owing to nanoscale metals with high efficiency in light absorption and scattering. They have several advantages over conventional display technology, including superior resolution and long-term preservation. However, most research on plasmonic color generation has been conducted for the development of static color generation, and dynamic tuning remains a challenging issue. To develop dynamic plasmonic colors, electrochemical, liquid crystal, and electromechanical methods have been proposed; however, there have been limitations in repeatability, flexibility, and scale-up processes. To address these problems, this work proposes a flexible dynamic plasmonic display using dielectric elastomer actuators (DEAs) to isotropically control the interdistance between the metal nanostructures, which can show dynamic coloration without polarization distortion. To replace the expensive and small-scale manufacturing approach, shadow masking and transfer technique with the anodic aluminum oxide (AAO) membrane was applied to realize large-scale and uniformly distributed Au nanodisc array. The differentiated and localized color change in the transmission and reflection modes, such as Janus's face, is realized by proper design of Au nanodisc array on the patterned transparent compliant electrodes formed by silver nanowires and PEDOT:PSS composites. Apparent and locally active color changes appeared in the transmission mode, but almost no color changes were observed in the reflection model by DEA actuation. The proposed system has the potential to activate color filters, cryptographic characters, and next generation display technologies.

Antibiofilm Metabolites from Marine-Derived Streptomyces sp. ZS-A31.

A novel compound streptothiomycin F (1), and a new natural product, N-(5-nitropentyl)acetamide (2), were discovered alongside ten previously identified compounds (3-12) through solid fermentation of marine-derived Streptomyces sp. ZS-A31 based on rice. The chemical structures of compounds 1-2 were elucidated using 1D and 2D NMR, as well as HRESIMS data analysis. Evaluation of all isolated compounds for their antibiofilm and antibacterial activities against P. aeruginosa was carried out using microdilution and crystal violet staining methods. Results highlighted the weak potency of the known compounds lumichrome (3) and vanillic acid (7) in inhibiting biofilm formation.

Low-temperature crystallization of BeO-assisted polycrystalline germanium layer for monolithic 3D integration

We demonstrated a new method for the low-temperature solid-phase crystallization (SPC) of germanium on beryllium oxide (BeO) films for monolithic 3D (M3D) integration. Using a wurtzite crystal BeO film, known for its high thermal conductivity of 370 W/m-k at 300 K and covalent bonding characteristics, as the underlying layer, we crystallized Ge at a reduced temperature of 410 °C. For the Ge-on-BeO, the formation of larger grains was consistently promoted at annealing temperatures of 410–500 °C, with a notable 125 % increase in the grain size at 500 °C compared to that at the SiO2 underlayer. The polycrystalline Ge layers crystallized on the BeO retained their tensile strain, as confirmed by the Raman spectra. Furthermore, its optical bandgap of ∼ 1.36 eV and average roughness of 0.847 nm at an annealing temperature of 450 °C make it more suitable for an M3D upper channel layer than Ge-on-SiO2. A comprehensive experimental analysis confirmed the enhanced crystallinity, stability, and channel properties of poly-Ge layers crystallized on BeO. Hence, this study developed a new method for the low-temperature SPC process and highlighted the potential of BeO as a crystallization-assistance thermal-management material for next-generation 3D integrated technology.

Thickness-dependent micro-fracture behaviors of pre-cracked aluminum plates by crystal plasticity finite element method and damage criteria

Despite the fact that fracture behaviors of pre-cracked metal plates were investigated by the crystal plasticity finite element method (CPFEM), the thickness effect on their micro-fracture behaviors is still not clear because of the different out-of-plane constraints. Here, mechanical properties and micro-fracture patterns of pre-cracked aluminum plates with different thicknesses are obtained by experiments, as well as by CPFEM combining with two damage criteria. First, finite element models are constructed based on grain morphologies of specimens achieved by electron back scattered diffraction experiments. Next, some key parameters required in CPFEM and two damage criteria are determined by fitting experimental stress–strain relationships. In particular, the factors affecting accuracy of FE predictions are clarified by CPFEM. Finally, thickness-dependent micro-fracture mechanisms of two different damage criteria in pre-cracked aluminum plates with various thicknesses and crack lengths are revealed by comparison with the experimental results and CPFEM. This investigation should be of great help for understanding thickness-dependent micro-fracture mechanisms of metal and other material plates.

Crystal Engineering-Driven Sunlight Responsiveness and Flexible Waveguide Transmission.

Here, a barbituric acid derivative containing pyrene rings (DPPT) was successfully synthesized, and two types of crystals were prepared by using crystal engineering methods. Orange sheet-like crystals (DPPT-O, observed in visible light), prepared in a DCM/CH3OH solution, exhibited brittleness and weak fluorescence emission, along with sunlight-induced bending and fracturing. Red needle-like crystals (DPPT-R, also observed in visible light), synthesized in a DCM/CH3CN solution, demonstrated elastic properties, strong fluorescence emission, and excellent optical waveguide performance (with an optical loss coefficient of 0.23-0.30 dB mm-1). Single-crystal data analysis revealed that the stacking arrangement of molecules critically influenced the elasticity of the crystals, while the reaction cavity size regulated the photomechanical properties of the crystals. This study achieved effective control over sunlight responsiveness and flexible optical waveguide transmission for the first time, providing innovative insights for the application of homogeneous organic polycrystalline molecular crystals in this field.

Analysis of compression response and coordinated deformation mechanism of bi-crystal Al-Cu-Mg-Ag alloy using CPFEM

In this paper, the compression behavior of Al-Cu-Mg-Ag bi-crystal samples at room temperature under different orientation combinations was studied. The stress-strain distribution of bi-crystal samples during the compression process was studied based on the crystal plastic finite element method (CPFEM). The deformation mismatch and slip transfer caused by the orientation combination of bi-crystal are discussed. The results show that the Al-Cu-Mg-Ag alloy bi-crystal samples with different orientations exhibit an anisotropic hardening response under compression. The combination of soft and hard orientation can coordinate the dislocation drive of the yield point, delay the elastoplastic transition of the yield point, and greatly improve the strength of the alloy. The mechanism of high strength of heterogeneous structure is proposed in this paper, which provides an important reference for the design of high strength heat resistant aluminum alloy for automobiles.

Structural and computational insights into two completely unanticipated Cu(II) and Ni(II) complexes derived from a bifunctional salamo-type bis(pyridine)-arm ligand

A bifunctional Salamo-type bis(pyridine)-arm ligand H2L (4,4′-Methyl-6,6′-pyridinenitrilomethylidyne-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol) was designed and synthesized, which can react with Cu(II) and Ni(II) nitrates to hydrolyze & break the C = N double bonds of new ligand H2L′ (4,4′-Methyl-6,6′-formal-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol). The ligand reacted with Cu(II) and Ni(II) salts to form respectively complexes [Cu(L′)] (1) and [Ni2(L′)(H2O)2](NO3)2 (2). They were elucidated by single crystal X-ray method. Many important noncovalent interactions, such as intramolecular hydrogen bonding, intermolecular hydrogen bonding and π···π stacking interactions, can be observed in the crystal structures of the two complexes. IR & UV–Vis absorbent spectroscopic analysis showed that the ligand unit is involved in the coordination with copper(II) and nickel(II) atoms, and ultraviolet titration and fluorescence titration spectra verified that the coordinating radios of the two complexes formed in liquid phase are in accordance with those of single-crystal X-ray diffraction. Through DFT theoretical calculations and electrostatic potential analyses (MESP) of the ligand and its complexes, the configuration of the ligand at the lowest energy were deeply understood, and it was demonstrated that the coordination reaction at salamo sites requires a great torsional force, and the weak intermolecular interaction force and the energy gaps of HOMO-LUMO orbitals were profoundly discussed, and the Cu(II) and Ni(II) complexes exhibit anomalous fluorescence enhancement behaviors.

Deterministic preparation of a dual-species two-ion crystal

The demand for efficient preparation methods for dual-species ion crystals is rapidly expanding across quantum technology and fundamental physics applications with trapped ions. We present a deterministic and efficient technique to produce such crystals, utilizing the segmented structure of a linear Paul trap. By precisely tailoring the trapping potentials, we can split, move, and discard parts of an ion chain. This process is automated in a sequence that converts a larger ion sample into the desired configuration. A critical component of our approach is the accurate identification of crystal constituents. This is achieved by matching the measured positions of fluorescing ions against theoretical expectations for larger crystals, thus facilitating the detection of nonfluorescing ions and enabling accurate ion counting. We demonstrate that our method reliably produces two-ion crystals within minutes. These results represent a significant advance in the production of two-species ion crystals with applications ranging from quantum logic spectroscopy and optical clocks to quantum computing and simulations with trapped ions. Published by the American Physical Society 2024

Multi-objective energy management in a renewable and EV-integrated microgrid using an iterative map-based self-adaptive crystal structure algorithm

The use of plug-in hybrid electric vehicles (PHEVs) provides a way to address energy and environmental issues. Integrating a large number of PHEVs with advanced control and storage capabilities can enhance the flexibility of the distribution grid. This study proposes an innovative energy management strategy (EMS) using an Iterative map-based self-adaptive crystal structure algorithm (SaCryStAl) specifically designed for microgrids with renewable energy sources (RESs) and PHEVs. The goal is to optimize multi-objective scheduling for a microgrid with wind turbines, micro-turbines, fuel cells, solar photovoltaic systems, and batteries to balance power and store excess energy. The aim is to minimize microgrid operating costs while considering environmental impacts. The optimization problem is framed as a multi-objective problem with nonlinear constraints, using fuzzy logic to aid decision-making. In the first scenario, the microgrid is optimized with all RESs installed within predetermined boundaries, in addition to grid connection. In the second scenario, the microgrid operates with a wind turbine at rated power. The third case study involves integrating plug-in hybrid electric vehicles (PHEVs) into the microgrid in three charging modes: coordinated, smart, and uncoordinated, utilizing standard and rated RES power. The SaCryStAl algorithm showed superior performance in operation cost, emissions, and execution time compared to traditional CryStAl and other recent optimization methods. The proposed SaCryStAl algorithm achieved optimal solutions in the first scenario for cost and emissions at 177.29 €ct and 469.92 kg, respectively, within a reasonable time frame. In the second scenario, it yielded optimal cost and emissions values of 112.02 €ct and 196.15 kg, respectively. Lastly, in the third scenario, the SaCryStAl algorithm achieves optimal cost values of 319.9301 €ct, 160.9827 €ct and 128.2815 €ct for uncoordinated charging, coordinated charging and smart charging modes respectively. Optimization results reveal that the proposed SaCryStAl outperformed other evolutionary optimization algorithms, such as differential evolution, CryStAl, Grey Wolf Optimizer, particle swarm optimization, and genetic algorithm, as confirmed through test cases.

A Machine-Learning-Assisted Crystalline Structure Prediction Framework To Accelerate Materials Discovery.

Modern crystal structure prediction methods based on structure generation algorithms and first-principles calculations play important roles in the design of new materials. However, the cost of these methods is very expensive because their success mostly relies on the efficient sampling of structures and the accurate evaluation of energies for those sampled structures. Herein, we develop a Machine-learning-Assisted CRYStalline Materials sAmpling sysTem (MAXMAT) aiming to accelerate the prediction of new crystal structures. For a given chemical composition, MAXMAT can generate efficient crystal structures with the help of a Python package for crystal structure generation (PyXtal) and can quickly evaluate the energies of these generated structures using a well-developed machine learning interaction potential model (M3GNET). We have used MAXMAT to perform crystal structure searches for three different chemical systems (TiO2, MgAl2O4, and BaBOF3) to test its accuracy and efficiency. Furthermore, we apply MAXMAT to predict new nonlinear optical materials, suggesting several thermodynamically synthesizable structures with high performance in LiZnGaS3 and CaBOF3 systems.

Stepwise crystallization method combining isotactic polypropylene-based plastic waste film to prepare high-performance polypropylene random copolymer

Upcycling of waste plastic film is increasingly important at the background of energy shortage and environmental crisis. However, direct reuse of the waste plastics as reworked material inevitably downgrades the mechanical properties. Herein, a stepwise crystallization method was used to enable the recycling of waste isotactic polypropylene (iPP) film value-added in iPP-based homocomposites. In detail, the effect of β-nucleating agent (β-NA) and iPP on crystallization behaviors of polypropylene random copolymer (PPR) was investigated at first. The stepwise crystallization procedure was further introduced to promote the β-crystallization of PPR/iPP/β-NA composites in which the crystal structures, polymorph compositions and phase morphologies were systematically researched. At last, impact behaviors of PPR/iPP/β-NA composites were characterized and a penitential toughening mechanism was proposed. It was found that the stepwise crystallization boosted β-crystallization and growth of rubbery phase during the isothermal procedure, resulting in an increase of relative β-crystal content and low temperature impact toughness from 0 % and 2.02 kJ/m2 of neat PPR to 33.4 % and 3.06 kJ/m2 of PPR/iPP/β-NA composites. This work provides a simple, implementable, and effective method for the recycling of waste iPP films and the low-temperature toughening of PPR.

Biofilm inhibition of denture cleaning tablets and carvacrol on denture bases produced with different techniques

ObjectivesThis study compares the biofilm inhibition effects of denture cleaning tablets, carvacrol, and their combined use against Candida albicans on denture bases produced with different techniques. Additionally, the surface roughness and contact angles of these denture bases were evaluated.Materials and methodsTest samples were prepared from four different denture base materials (cold-polymerized, heat-polymerized, CAD/CAM milling, and 3D-printed). The surface roughness and contact angles of the test samples were measured using a profilometer and goniometer, respectively. For the evaluation of biofilm inhibition, samples were divided into 5 subgroups: Corega and carvacrol, separately and combined treatments, positive (inoculated with C. albicans) and negative control (non-inoculated with C. albicans, only medium). Biofilm mass was determined using the crystal violet method. An additional prepared test sample for each subgroup was examined under scanning electron microscopy (SEM).ResultsThe surface roughness values of the 3D-printed test samples were found to be statistically higher than the other groups (P < .001). The water contact angle of all test materials was not statistically different from each other (P > .001). Corega and carvacrol, separately and combined, significantly decreased the amount of biofilm on all surfaces (P < .0001). Treatment of corega alone and in combination with carvacrol to the 3D-printed material caused less C. albicans inhibition than the other groups (P < .001; P < .05).ConclusionsThe surface roughness values of all test groups were within the clinically acceptable threshold. Although Corega and carvacrol inhibited C. albicans biofilms, their combined use did not show a synergistic effect.Clinical relevanceCarvacrol may be used as one of the disinfectant agents for denture cleaning due to its biofilm inhibition property.