Modification Of Material Properties Research Articles

Doping effect of Zn on structural and optical properties of CuO nanostructures prepared by wet chemical precipitation process

CuO exhibits superior properties in semiconducting technology. The preparation with thermal activation can be found in several previous reports. Consequently, the synthesizing process at room temperature is interesting because of no energy consumption, reducing production costs. For material property modification, incorporated metal atoms affect the morphology and properties of the host lattice. Accordingly, the purpose of this work is to study the consequence of Zn doping on the structural and optical properties of CuO, prepared via room temperature synthesizing process of wet chemical precipitation without further calcination. Various analytical techniques studied crystal structure, morphology, chemical composition, and optical properties. X-ray Diffraction (XRD) analysis revealed the formation of a pure monoclinic CuO phase with crystallite size in the range of 25–38 nm. As increasing Zn content, structural and optical properties of doped CuO were changed comparing with pure CuO. Scanning electron microscope (SEM) displayed morphology transformation from irregular plates to nanoparticles. TEM images elucidated the formation of crystals in the different directions of block aggregation. Specific surface area (SSA) revealed a reducing value from 17.2567 to 16.6128 m2/g. PL emission assigned to near band-edge emission at 445 nm and oxygen vacancy existence at 519 nm. Comparison with pristine CuO, PL intensity quenching was found in doped CuO. The reduction of electron-hole recombination corresponds to the increasing energy bandgap with linear tendency, appearing at 2.80–2.94 eV. Finally, this synthesizing route is effective and can extend synthesizing technology to other doped metal oxide nanostructures.

СТВОРЕННЯ ТА ВИКОРИСТАННЯ КОМПОЗИТУ В ЯКОСТІ СИЛОВОЇ КОНСТРУКЦІЇ З ВКЛЮЧЕННЯМ МАГНІТОСТРИКЦІЙНОГО МАТЕРІАЛУ

In our time a new generation of materials - «intellectual» materials - is rapidly developing. Intelligent materials are materials that react in a certain way to changes in the state of the environment or the influence of force fields, vibrations or oscillations and radiations. This reaction results in the modification of material properties, geometry and its adaptation to changes in operating conditions. Constructions are made of intelligent materials, in addition to the traditional functions of taking operational loads and ensuring load and strength, can provide self-monitoring, identification and localization of fatigue injuries. For example, the use of magnetostrictive materials makes it possible to reduce the oscillations or to absorb vibrations and to regulate the stringency. The subject of this work is the analysis of properties that can be obtained on a composite by changing the volumetric part of a magnetostrictive material. The Terfenol-D alloy, which has the most pronounced magnetostrictive properties, was chosen as a magnetostrictive material. The one of the properties of the Terfenol-D alloy is a significant change Young's modulus with change in the magnetic field strength. And also the predicted and experimental results of the change in Young's modulus for pre-loaded samples with compressive forces in a magnetic field were compared. To create a model of a composite material with the Terfenol-D alloy, Material Designer was used - the module of the Ansys system. This module allowed the creation of a composite material for modeling using base materials with known material properties. In the article, the properties of a composite material were obtained using the magnetostrictive material Terfenol-D, and an assessment of the possibility of creating a load-bearing design structure was presented. Material Designer made it possible to create a composite material for modeling using base materials with known material properties. In the article, the properties of a composite material were obtained using the magnetostrictive material Terfenol-D, and an assessment of the possibility of creating a load-bearing structure was presented.

Individual response to multi-density midsoles to minimise biomechanical injury risk factors of Achilles tendinopathy in distance running

Modifications of midsole geometry and material properties are essential footwear design features to prevent overuse injuries (OIs) in distance running. With an injury frequency of 10.9%, Achilles t...

Reconstruction of depth resolved strain tensor in off-axis single crystals: Application to H+ ions implanted LiTaO3

In the context of growing interest in strain engineering, we present a theoretical protocol for the reconstruction of extrinsic and intrinsic strain tensors in single-crystals attached to a template, with an arbitrary oriented coordinate system. Input data for the protocol are extrinsic deformations of lattice planes, i.e., measured with reference to a template. By combining the protocol with elasticity theory, material property modification can be elucidated. Different methods for strain measurements can take advantage of this approach. It has been applied for reconstruction of strain tensor depth distribution in off-axis LiTaO3 crystals implanted with H+ ions, which is the key step for piezoelectric thin film-on-insulator fabrication by the Smart Cut process. Modifications of composition, lattice parameters, and elastic constants are indicated and discussed.

Sensitivity to Input Parameters of Failure Detection Methods for Out-of-Plane Loaded Glass Panels in Fire

In recent years, glass has been a largely used material for load-bearing or non-structural components in buildings and constructions. For this reason, dedicated calculation methods and approaches are required for the major loading and boundary conditions that are of technical interest for safe design purposes. Among others, the resistance and mechanical performance of glass elements under fire exposure still represents an open challenge. This paper elaborates on the failure detection methods for out-of-plane loaded glass panels that are subjected to fire loading and simultaneous mechanical loads. As known, the conventional method for thermal failure detection is based on the maximum temperature gradient in glass, and its comparison with a set of allowable standardized values. However, especially for ordinary glass components in buildings that are required to sustain combined mechanical loads, the overall structural performance is even more complex to predict. This design issue is given to a combination of pure mechanical aspects (i.e., sustained loads and corresponding stress–strain analysis) and thermo-physical phenomena, that depend on the progressive modification of material properties while increasing temperatures. This research study, accordingly, investigates the sensitivity of input parameters on the failure time of a given glass element under fire and sustained mechanical loads. A major advantage is taken from finite element (FE) numerical analyses and standardized failure detection methods of literature, that are selected for comparative purposes. Further, the paper also introduces the “stress approach” that can be used to quantify (in place of the conventional thermal gradient) the actual effects of assigned thermal exposure and mechanical loads.

Effects of p-type (Ag, Cu) dopant on the electronic, optical and photocatalytic properties of MoS2, and impact on Au/Mo100-x-yAgxCuyS2 performance

MoS2 is an alternative of graphene due to its intriguing properties and it is necessary to modify the properties for achieving p-MoS2 and complementary device applications. Doping is one of the most prevalent techniques for modification of materials properties and fabricating p-MoS2. Herein, we report on Ag and Ag-Cu doped MoS2 investigated by theoretical and experimental studies. Detailed study of DFT highlights the confirmation of p-type MoS2. The band gap can be tuned from 1.21 to 0.51 eV (theoretically) and 1.92–1.30 eV (experimentally). The enhancement of absorption in the visible region attributed to Ag and Ag-Cu doping. The conduction band (CB) edge potential is smaller in negative than H+/H2 (0.0 eV) for undoped, Ag = 2.5% and Ag-Cu (Ag = 2.5, Cu = 10%) doped MoS2, hence the photogenerated electrons can weakly reduce H+ to produce H2. While the deeper valence band (VB) edge potential than O2/H2O (1.23 eV) confirms that the holes created upon photon absorption strongly shows the ability for water oxidation. However for other doping both potential edges are more positive which insights strong oxidative material. Interestingly, the theoretical calculation suggests that the CB edge potential should be upward shifting for enhancing the photocatalytic activity of MoS2. EDX and XPS measurements disclose the presence of Mo, S, Ag and Cu elements in the thin films. Furthermore, decreasing forward current and shifting threshold voltage (VT) toward higher voltage in (Ag, Cu) doped Au/Mo100-x-yAgxCuyS2 insights p-type MoS2. Therefore, these demonstrations could be extended its applications to be enable high-performance electronic and optoelectronic devices.

Модифицирование материалов при воздействии мощных ионных пучков

The review is devoted to the use of powerful submicrosecond ion beams for the synthesis and modification of material properties. Powerful ion beams, originally developed for the problems of inertial thermonuclear fusion, have been increasingly used over the past 30 years as a powerful pulsed heating source providing ample opportunities for modifying the surface layer of materials. By varying the key parameters of the beams, such as the composition (type of ions), the duration of the accelerating pulse (10 ns – 1 μs), the kinetic energy of the ions (0.1 – 1 MeV), the energy density transmitted by the beam to the target surface per pulse (0.1 – 50 J/cm2), the main areas of application of high-power ion beams in materials science were determined: modification of the surface layer by ultrafast quenching, melting and ultrafast recrystallization with the formation of micro- and nanostructures, pulsed implantation of ions accompanied by energetic action, deposition of thin films and synthesis of nanosized powders from ablative plasma.

Recent Advances and Prospects of Atomic Substitution on Layered Positive Materials for Lithium‐Ion Battery

AbstractThis work not only summarizes the previous doping research that focused on the optimization of a bulk doping composition but also introduces a new doping strategy, namely, “electrochemical reaction mechanism control doping.” The new electrochemical mechanism control technology enables the study of the precise deterioration mechanism of layered cathode materials for Li‐ion batteries (LIBs). Accordingly, tremendous efforts have been devoted to the development of various types of layered cathode materials, such as lithium‐rich, nickel‐rich, and cobalt‐rich materials, by using an electrochemical functioning doping method. This progress report also gives a perspective on potential future directions for this field. In this context, detailed methodological approaches are suggested for advanced doping studies, where the consideration of the doping method takes significance as great as designing doping configurations, e.g., chemical composition, doping depth, and doping site control, for the modification of battery material properties. As an instance of the methodological approaches for doping studies, a new “secondary doping” is shown with exemplary experimental results showing that functioning dopants (primary dopants) are homogeneously dispersed on the layered cathode materials by using supporting dopants (secondary dopants). This study will provide insights into the future direction of doping research of LIBs, as well as the history of the development of atomic substitution in layered cathode materials.

Modeling on mechanical behavior and damage evolution of single-lap bolted composite interference-fit joints under thermal effects

This paper reports the modeling method and outcomes of mechanical performance and damage evolution of single-lap bolted composite interference-fit joints under extreme temperatures. The anisotropic continuum damage model involving thermal effects is established on continuum damage mechanics which integrates the shear nonlinearity constitutive relations characterized by Romberg-Osgood equation. The temperature-induced modification of thermal strains and material properties is incorporated in stress-strain analysis, extended 3D failure criteria and exponential damage evolution rules. The proposed model is calibrated and employed to simulate behavior of composite joints in interference fitting, bolt preloading, thermal and bearing loading processes, during which the influence of interference-fit sizes, preload levels, laminate layups and service temperatures is thoroughly investigated. The predicated interfacial behavior, bearing response and failure modes are in good agreement with experimental tests. The numerical model is even capable of reflecting some non-intuitive experimental findings such as residual stress relaxation and matrix softening at elevated temperatures.

A three-dimensional multiscale finite element model of bone coupling mineralized collagen fibril networks and lamellae

Despite evidence of contribution of mineralized collagen fibrils (MCF) to both the microscale elastic and fracture response of bone, the extent of influence of MCF orientation and material property variation on the lamellar scale mechanical properties is still not well quantified. To this end, in this study, we developed a three-dimensional multiscale finite element model that linked submicroscale models of MCF networks to microscale models of several lamellae. The developed models evaluated the individual and relative influence of MCF orientation as well as material property variation due to MCF mineral distribution and interaction on the lamellar scale mechanical response of bone. The simulation results showed that the elastic modulus, ultimate strength, and fracture energy at the lamellar scale decreased as the angle between the main axis of MCFs and loading direction increased. The heterogeneity in mineral distribution along MCFs did not lead to a significant difference in the mechanical behavior at the lamellar scale compared to the material property heterogeneity introduced in the models due to MCF orientation variation. Variation in the interaction between MCFs at the submicroscale had a substantial influence on the lamellar scale mechanical properties. In summary, this study established a multiscale model that linked MCFs to lamellae providing the capability of quantifying the relative influence of modifications in material and organizational properties of MCFs due to age, diseases, and treatments on the fracture processes at the lamellar length scale.

A low-parametric rhombic microstructure family for irregular lattices

New fabrication technologies have significantly decreased the cost of fabrication of shapes with highly complex geometric structure. One important application of complex fine-scale geometric structures is to create variable effective elastic material properties in shapes manufactured from a single material. Modification of material properties has a variety of uses, from aerospace applications to soft robotics and prosthetic devices. Due to its scalability and effectiveness, an increasingly common approach to creating spatially varying materials is to partition a shape into cells and use a parametric family of small-scale geometric structures with known effective properties to fill the cells. We propose a new approach to solving this problem for extruded, planar microstructures. Differently from existing methods for two-scale optimization based on regular grids with square periodic cells, which cannot conform to an arbitrary boundary, we introduce cell decompositions consisting of (nearly) rhombic cells. These meshes have far greater flexibility than those with square cells in terms of approximating arbitrary shapes, and, at the same time, have a number of properties simplifying small-scale structure construction. Our main contributions include a new family of 2D cell geometry structures, explicitly parameterized by their effective Young's moduli E , Poisson's ratios v , and rhombic angle α with the geometry parameters expressed directly as smooth spline functions of E, v , and α. This family leads to smooth transitions between the tiles and can handle a broad range of rhombic cell shapes. We introduce a complete material design pipeline based on this microstructure family, composed of an algorithm to generate rhombic tessellation from quadrilateral meshes and an algorithm to synthesize the microstructure geometry. We fabricated a number of models and experimentally demonstrated how our method, in combination with material optimization, can be used to achieve the desired deformation behavior.

Triaxial Magnetic Flux Emanation in Response to Uniaxial Electric Field in Magnetoelectric Composite Cylinder Structure

Magnetoelectricity in bulk strain‐mediated multiferroic composites has been growing in attention for sensor and actuator applications. For actuator applications, where electric to magnetic coupling is utilized, the magnetoelectric composite alters the magnetic field which it is within resulting in full‐field spatial and directional changes to the magnetic flux. To grasp a better understanding of the full‐field magnetic behavior of a magnetoelectric composite with a complex geometry, multiple magnetic flux measurements in different locations and directions are taken to unveil interesting behaviors and phenomena such as modality and postfabrication material property modification. Remarkably, a significant multidirectional magnetic flux is measured at a distance away from the composite which can be harnessed to improve the efficiency of multiferroic actuators. In addition, the intensity and directionality of the magnetic flux is highly tunable by modifying the frequency and bias magnetic field depending on the need for the application.

Nanoscale lattice strains in self-ion implanted tungsten

Developing a comprehensive understanding of the modification of material properties by neutron irradiation is important for the design of future fission and fusion power reactors. Self-ion implantation is commonly used to mimic neutron irradiation damage, however an interesting question concerns the effect of ion energy on the resulting damage structures. The reduction in the thickness of the implanted layer as the implantation energy is reduced results in the significant quandary: Does one attempt to match the primary knock-on atom energy produced during neutron irradiation or implant at a much higher energy, such that a thicker damage layer is produced? Here we address this question by measuring the full strain tensor for two ion implantation energies, 2 MeV and 20 MeV in self-ion implanted tungsten, a critical material for the first wall and divertor of fusion reactors. A comparison of 2 MeV and 20 MeV implanted samples is shown to result in similar lattice swelling. Multi-reflection Bragg coherent diffractive imaging (MBCDI) shows that implantation induced strain is in fact heterogeneous at the nanoscale, suggesting that there is a non-uniform distribution of defects, an observation that is not fully captured by micro-beam Laue diffraction. At the surface, MBCDI and high-resolution electron back-scattered diffraction (HR-EBSD) strain measurements agree quite well in terms of this clustering/non-uniformity of the strain distribution. However, MBCDI reveals that the heterogeneity at greater depths in the sample is much larger than at the surface. This combination of techniques provides a powerful method for detailed investigation of the microstructural damage caused by ion bombardment, and more generally of strain related phenomena in micro-volumes that are inaccessible via any other technique.

Synthesis, crystal structure, polymorphism and microscopic luminescence properties of anthracene derivative compounds

Anthracene derivative compounds are currently investigated because of their unique physical properties (e.g. bright luminescence and emission tunability), which make them ideal candidates for advanced optoelectronic devices. Intermolecular interactions are the basis of the tunability of the optical and electronic properties of these compounds, whose prediction and exploitation benefit from knowledge of the crystal structure and the packing architecture. Polymorphism can occur due to the weak intermolecular interactions, requiring detailed structural analysis to clarify the origin of observed material property modifications. Here, two silylethyne-substituted anthracene compounds are characterized by single-crystal synchrotron X-ray diffraction, identifying a new polymorph in the process. Additionally, laser confocal microscopy and fluorescence lifetime imaging microscopy confirm the results obtained by the X-ray diffraction characterization, i.e. shifting the substituents towards the external benzene rings of the anthracene unit favours π-π interactions, impacting on both the morphology and the microscopic optical properties of the crystals. The compounds with more isolated anthracene units feature shorter lifetime and emission spectra, more similar to those of isolated molecules. The crystallographic study, supported by the optical investigation, sheds light on the influence of non-covalent interactions on the crystal packing and luminescence properties of anthracene derivatives, providing a further step towards their efficient use as building blocks in active components of light sources and photonic networks.

Progress in low energy high intensity ion implantation method development

New results on the equipment development and advancement of the method of high-intensity ion implantation of metal, gases and low-energy semiconductors providing a long range effect of dopants penetration are presented in the article. The results of the research and development of plasma-immersion systems for the formation of ion beams with a current density of tens and hundreds of mA/cm2, a beam current exceeding 1 A at kilovolt accelerating voltages using ion extraction and beam focusing systems as part of a sphere or cylinder are shown. A comparative analysis of various systems, their advantages and disadvantages depending on the purpose are presented.The concept of low energy high intensity ion implantation (LEHI3) method is described. The features of the method as applied to the problems of deep modification of the microstructure and operational characteristics of metals and alloys are analyzed. The report presents the results of experimental studies of LEHI3 of aluminum, titanium, nitrogen into various structural materials. The possibility of ion doping of materials at depths of several tens and hundreds of micrometers is shown. Data are presented on the changes in the elemental composition, microstructure and properties of various materials depending on the ion current density of 10–500 mA/cm2, ion energy, implantation temperature and irradiation fluence of 1018–1022 ion/cm2.Based on the analysis of the obtained experimental data, the directions of further research are discussed in the framework of the development of the physical and technological foundations of the LEHI3 method of material properties modification at depths that are orders of magnitude greater than the projective ranges of ions.

利用飞秒激光照射调控氧化石墨烯表面的浸润性能（特邀）

Modification of material surface morphology and properties based on femtosecond laser irradiation is a novel processing technology developed in recent years, which has shown unique advantages in high-speed, large-area and periodic subwavelength structure fabrications. Here this method was employed to rapidly fabricate uniform subwavelength grating structures on the surface of GO film, and then the processing mechanisms, the change of morphology and liquid wettability were investigated comprehensively. Through using different experimental parameters such as the laser power and the scanning speed, the rGO grating structures with variable depth-width ratios and surface roughness were obtained, leading to the controllable wettability with the liquid contact angles in a range of 15° to 75°, and their contact angles were found to increase by an average of 20° after 20 days in the air. Our work lays a solid foundation for femtosecond laser micro/nano-processing of two-dimensional materials. It is expected to have the future applications in the field of droplet collection, microfluidic control, and so on.

Frontal Ring-Opening Metathesis Copolymerization: Deviation of Front Velocity from Mixing Rules.

Frontal ring-opening metathesis polymerization (FROMP) of dicyclopentadiene (DCPD) shows promise for rapid, energy-efficient manufacturing of high-performance polymers and composites. Copolymerization in FROMP allows for systematic modification of materials properties while retaining the benefits of the DCPD system such as low cost of the monomer and excellent mechanical properties of the resulting polymer. While the copolymerization reactivity and copolymer properties generally exhibit monotonic dependence on monomer composition as predicted by simple, empirical mixing rules, we discovered that the frontal copolymerization behavior of DCPD with a dinorbornenyl (di-NBE) cross-linker deviates significantly from that expected relationship. As the comonomer content increases, the FROMP reaction shows a nonmonotonic increase in front velocity with intermediate compositions 40% faster than either pure component. We then studied the behavior of a series of comonomers, analyzed several factors (such as thermodynamic and kinetic properties) that might influence front velocity, and found that the nonmonotonic trend mainly results from the cross-linked structure. This copolymerization system provides a promising strategy to tune materials properties (such as glass transition temperature) and simultaneously improve the efficiency in FROMP-based materials manufacturing.

Ultrahigh elastically compressible and strain-engineerable intermetallic compounds under uniaxial mechanical loading

Intermetallic compounds possess unique atomic arrangements that often lead to exceptional material properties, but their extreme brittleness usually causes fracture at a limited strain of less than 1% and prevents their practical use. Therefore, it is critical for them to exhibit either plasticity or some form of structural transition to absorb and release a sufficient amount of mechanical energy before failure occurs. This study reports that the ThCr2Si2-structured intermetallic compound (CaFe2As2) and a hybrid of its structure (CaKFe4As4) with 2 µm in diameter and 6 µm in height can exhibit superelasticity with strain up to 17% through a reversible, deformation-induced lattice collapse, leading to a modulus of resilience orders of magnitude higher than that of most engineering materials. Such superelasticity also can enable strain engineering, which refers to the modification of material properties through elastic strain. Density functional theory calculations and cryogenic nanomechanical tests predict that superconductivity in CaKFe4As4 could be turned on/off through the superelasticity process, before fracture occurs, even under uniaxial compression, which is the favorable switching loading mode in most engineering applications. Our results suggest that other members with the same crystal structure (more than 2500 intermetallic compounds) and substitution series based on them should be examined for the possibility of manifesting similar superelastic and strain-engineerable functional properties.

Optic nerve head damage relation to intracranial pressure and corneal properties of eye in glaucoma risk assessment.

This work presents results from numerical simulations of optic nerve head's (ONH) biomechanical behavior during exposure to elevated intraocular (IOP) and/or intracranial pressure (ICP) for ocular hypertension conditions. At the same time, a range of geometric and material properties of the eye structure and their interrelation with elevated IOP and ICP values are investigated. These simulations are performed on a generic model of the eye, which allows parametrical modification of geometric and material properties. Our main interest is in measuring ONH's potential damage in ocular hypertension due to intracranial pressure. Simulation results indicate a significant role of ICP in post-laminar neural tissue failure and a possible role of central corneal thickness (CCT) and scleral modulus in clinical assessment and treatment of patients with ocular hypertension (OHT). Specifically, CCT was found to affect ONH at early stages of damage in ocular hypertension conditions, and high scleral modulus seems to result in reduced shear failure in lamina cribrosa in a similar OHT state. These findings suggest that CCT could be a risk factor for glaucoma in OHT patients at initial stage along with cornea stiffness. Graphical abstract Graphical abstract.

C-H Functionalization of Commodity Polymers.

Synthetic manipulation of polymer substrates is one of the oldest and most reliable methods to increase the functional diversity of soft materials. Modifying the chemical structure of polymers that are already produced on a commodity scale leverages the current high-volume and low-cost production of commodity plastics for the discovery of modern materials. A myriad of polymer C-H functionalization methods have been developed which enable the modification of material properties on both a laboratory and industrial scale. More recently, driven by advances in C-H activation, photoredox catalysis, and radical chemistry, chemoselective approaches have emerged as a means to impart precise functionality onto commodity polymer substrates. This Review discusses the historical significance of and contemporary advances in the C-H functionalization of commodity polymers. The conceptual approach outlined herein presents exciting new directions for the field, including increasing the value of otherwise pervasive materials, uncovering entirely new material properties, and a viable path to upcycle post-consumer plastic waste.