Different Classes Of Materials Research Articles

Transition from surface phonon-polariton to surface phonon–plasmon-polariton by thermal injection of free carriers

Surface phonon-polariton, surface plasmon-polariton, and surface phonon–plasmon-polariton are evanescent electromagnetic waves confined to the surfaces of different classes of materials, which gives each of them particular characteristics suitable for diverse applications. Natural or forced injection of free carriers in a dielectric may change the surface phonon-polariton into a surface phonon–plasmon-polariton. Understanding this effect provides an insight into the fundamental physics of surface electromagnetic waves on dielectrics and offers tools that can be used to develop new technologies. In this contribution, we experimentally study the transition from surface phonon-polariton to surface phonon–plasmon-polariton on a yttrium-doped aluminum nitride polycrystalline substrate by thermal injection of free carriers. We perform this study using reflectivity measurements in the far- and mid-infrared spectral range and at a variable temperature, taking the necessary precautions to eliminate any errors that may arise from measurement artifacts and inaccurate analysis of the spectra. We demonstrate that thermal injection of a significant free carrier density can tune the surface phonon-polariton into a much shorter mean free path surface phonon–plasmon-polariton.

Direct Ink Writing: A 3D Printing Technology for Diverse Materials.

Additive manufacturing (AM) has gained significant attention due to its ability to drive technological development as a sustainable, flexible, and customizable manufacturing scheme. Among the various AM techniques, direct ink writing (DIW) has emerged as the most versatile 3D printing technique for the broadest range of materials. DIW allows printing of practically any material, as long as the precursor ink can be engineered to demonstrate appropriate rheological behavior. This technique acts as a unique pathway to introduce design freedom, multifunctionality, and stability simultaneously into its printed structures. Here, a comprehensive review of DIW of complex 3D structures from various materials, including polymers, ceramics, glass, cement, graphene, metals, and their combinations through multimaterial printing is presented. The review begins with an overview of the fundamentals of ink rheology, followed by an in-depth discussion of the various methods to tailor the ink for DIW of different classes of materials. Then, the diverse applications of DIW ranging from electronics to food to biomedical industries are discussed. Finally, the current challenges and limitations of this technique are highlighted, followed by its prospects asaguideline toward possible futuristic innovations.

Multiscale Mechanical Performance of Wood: From Nano- to Macro-Scale across Structure Hierarchy and Size Effects.

This review describes methods and results of studying the mechanical properties of wood at all scales: from nano- to macro-scale. The connection between the mechanical properties of material and its structure at all these levels is explored. It is shown that the existing size effects in the mechanical properties of wood, in a range of the characteristic sizes of the structure of about six orders of magnitude, correspond to the empirical Hall-Petch relation. This “law” was revealed more than 60 years ago in metals and alloys and later in other materials. The nature, as well as the particular type of the size dependences in different classes of materials can vary, but the general trend, “the smaller the stronger”, remains true both for wood and for other cellulose-containing materials. The possible mechanisms of the size effects in wood are being discussed. The correlations between the mechanical and thermophysical properties of wood are described. Several examples are used to demonstrate the possibility to forecast the macromechanical properties of wood by means of contactless thermographic express methods based on measuring temperature diffusivity. The research technique for dendrochronological and dendroclimatological studies by means of the analysis of microhardness and Young’s modulus radial dependences in annual growth rings is described.

On a unique constitutive equation for steady state isotropic optimal structural superplastic deformation in all classes of materials

Structural Superplasticity in materials has been reported in so many different classes of materials that there is a case to state that this phenomenon is (near)-ubiquitous. Yet, many authors have proposed different rate controlling processes for different superplastic materials. Such an approach goes against Newton’s (Principia, Part 3) axiom that “to the same natural effects we must, so far as possible, assign the same causes”. In contrast, a viewpoint also exists that steady state, isotropic, optimal structural superplastic deformation in different classes of materials can be attributed to a grain-boundary-sliding-rate-controlled process that develops to a mesoscopic scale (defined to be of the order of a grain diameter or more). If this were the case, it should be possible to generate in properly normalized spaces material-independent “universal” curves (2D) and surfaces (3D) for the relationships among the different experimental variables/parameters like stress, strain rate, strain rate sensitivity index, temperature, real activation energy for the rate controlling process and viscosity. In this paper, by a careful analysis of experimental data concerning 175 states of superplastic materials of different classes it is demonstrated that such universal curves and surfaces indeed exist. The existence of such universal curves and surfaces that describe the phenomenology of steady state, isotropic, optimal structural superplastic deformation in different classes of materials in terms of unique equations reinforces the view experimentally arrived at that a unique physical mechanism of deformation is responsible for the near-ubiquitous phenomenon of steady state, isotropic, optimal structural superplasticity.

Volume dependent fracture energy and brittle to quasi-brittle transition in intermetallic alloys

Intermetallic alloys such as titanium aluminide (TiAl) are lightweight with superior specific strength and high temperature oxidation resistance. They have a potential to replace heavier nickel based super alloys in low pressure high temperature sections of an aero engine. To facilitate an industry wide implementation, it is however indispensable to develop physically accurate computational methods which account for key deformation and fracture mechanisms. This assists the virtual prototyping required for the new product development using TiAl alloys. In this work, the quasi-brittle and volume dependent behavior of TiAl alloys is experimentally and numerically investigated. A total number of 29 geometrically identical TiAl specimens of three different sizes are tested in a three-point bending setup to investigate the volume dependence of fracture properties. In addition, three compact tension tests with identical specimen geometries are performed to analyze brittle to quasi-brittle transition and a switch in failure mechanism. Since the material fracture is observed to be preceded by plasticity, a theoretical and numerical framework of phase field ductile fracture which accounts for both elastic and plastic work densities is applied. The averaged fracture energy density for each test is evaluated numerically which is found to be lower for larger volumes. The work concludes with the proposal of an empirical law relating the fracture energy density with the specimen volume. Data from literature for different classes of materials is used for validation of the proposed empirical law. The mechanisms of transition from brittle to quasi-brittle fracture are investigated on the basis of local stress triaxiality in three-point and compact tension simulations.

Signal Processing for Advanced Materials [From the Guest Editors

The development of new materials has been a hallmark of technological advancement since at least the Bronze Age, when copper and tin were alloyed to create tools that had properties favorable to those made from stone. For thousands of years, until the development of microscope imaging, new materials continued to be developed “blindly,” without any understanding of the effects of the structure at the micro- or nanoscale on the observable properties of a material. With the advent of sensing modalities, such as electron microscopy and X-ray tomography, huge amounts of microstructural data of many different classes of materials have become available.

Damage evaluation of the power plants materials based on the AE model of material degradation under high-cyclic fatigue

Modern mechanical engineering products are expected to have an increased lifetime at reduced cost. In order to enable this development, new and improved methods of structural materials strengthening need to be found. Mathematical modelling of the mechanical behaviour of the products in the conditions of fatigue, taking into account various operational, design and technological factors does not provide the necessary accuracy and has to be verified in long-term tests. Therefore, development of a methodology for predicting the limiting state of the structural materials under the long-term periodic load by non-destructive control methods, in particular the acoustic emission (AE) method, remains topical.Within this work, custom-designed model samples of nickel- and titanium-based alloys, as well as carbon and alloyed steel have been studied in comparison. The samples were fabricated both in standard technological process and including ultrasonic surface hardening. Features of cyclic AE characteristics that are identical for different classes of materials with different technological inheritance are described. Based on the obtained results, the relationships between the informative parameters of AE and the criteria of the limiting state of the studied materials for power plants under the high-cycle fatigue conditions are established. This enables assessment of the effectiveness of the technological measures aimed at increasing the life of parts of the power plants, based on non-destructive AE control.

Trasmigrazioni: cultura materiale e sviluppo dell'identità. Alcune riflessioni sulla produzione di San Vincenzo al Volturno

The text analyzes the ornamental culture of the monastery of San Vincenzo al Volturno, through the comparison between different classes of materials. Through the analogies between the ornamental motifs, we tried to reconstruct their creative process, on a perceptual basis. The study, in fact, focuses on the relationship between the individual and the environment, exploiting the theories of Gibson, applying them to a particular context such as monasteries. The goal is to demonstrate how the continuous use of space determines the acquisition of visual information, which, stored in memory, is re-proposed during the creative process. Especially, it is the daily journey of the rooms that guarantees the memorization of the signs and, at the same time, their updating, through the change of perspective that occurs with movement. In the last part, we discuss the perceptive effects of the aniconic paintings in the crypt of Joshua.

Computational insights into efficient CO2 and H2S capture through zirconium MOFs

Separation of CO2 involving mixtures is relevant to the various industrial settings and preserving environment for which different classes of materials including metal-organic frameworks (MOFs) have been researched. Herein, CO2/CO, CO2/H2, CO2/N2, and H2S/CO2 separation properties of the zirconium MOFs are computationally investigated mimicking vacuum swing adsorption (VSA) process. Structure-performance relationships are established and the best performing adsorbent materials are determined considering three performance metrics: adsorption selectivity, working capacity, and regenerability. For CO2/CO separation in dry conditions, PCN-59, BUT-10, and PCN-58 are identified to be the top three materials with CO2/CO selectivities of 219.8, 47.2, and 28.6, CO2 working capacities of 6.9, 5.3, and 4.0 mol/kg, CO2 regenerabilities of 63.3, 82.1, and 87.2 %, successively. In humid conditions, UiO-66-OH and MOF-805 appear promising for CO2/CO separation. Regarding CO2/H2 separation in dry conditions, PCN-59, BUT-10, and LIFM-94 are ranked as the top three MOFs exhibiting CO2/H2 selectivities of 1445.6, 378.1, and 411.3, CO2 working capacities of 3.6, 2.4, and 2.2 mol/kg, and CO2 regenerabilities of 56.6, 84.9, and 83.9 %, successively. These three materials are also found to be the top three materials for CO2/N2 separation in dry conditions with CO2/N2 selectivities of 346.0, 53.3, and 54.9, CO2 working capacities of 3.6, 2.3, and 2.2 mol/kg, and CO2 regenerabilities of 56.3, 84.1, and 83.9 %, successively. For CO2/H2 and CO2/N2 separation in humid conditions, UiO-66-NH2 is potentially useful. Considering H2S/CO2 separation in dry conditions, NU-1101, PCN-58, and LMOF-1 are identified to be the best three MOFs attaining H2S/CO2 selectivities of 109.7, 30.9, and 90.7, H2S working capacities of 1.6, 2.3, and 1.2 mol/kg, and H2S regenerabilities of 43.0, 56.4, and 43.7 %, respectively. All top materials for H2S/CO2 separation show relatively large water affinities (PCN-57 having the smallest affinity) which might render them inefficient for H2S/CO2 separation in humid conditions. Adsorbate density profiles are generated for the top 3 materials to elucidate the adsorption mechanisms for each gas separation. A comparison of predictions based on PACMOF and EQeq charges demonstrates drastic differences in material rankings, and separation performance metrics.

Spectroscopic behavior of various materials in a GEO simulated environment

Artificial objects currently populating Earth orbital regimes can be distinguished by comparing remote observational data to that of optical measurements within the visible (VIS) and near infrared (NIR) spectral regions of materials obtained in the laboratory. Careful comparison of spectrally resolved observations with laboratory-based material irradiation experiments can provide a tool for remote diagnosis and anomaly resolution. However, the spectral signatures of many materials change as a function of exposure to radiation in geosynchronous Earth orbit (GEO). In order for remote characterization to be a viable characterization technique, the evolution of material optical properties (VIS-NIR) upon exposure to the GEO environment must be understood. To this end, we have studied the reflectance of several commonly used spacecraft materials including organic polymers, solar cell coverglasses, black thermal control paint, and carbon-carbon (C–C) matrix composite as a function of exposure to high energy electron irradiation in order to mimic the harsh environment of GEO. It was found that different classes of materials exhibit large variation in radiation stability resulting in the development of unique spectral characteristics.

Membranes for olefin–paraffin separation: An industrial perspective

In the next decade, separation science will be an important research topic in addressing complex challenges like reducing carbon footprint, lowering energy cost, and making industrial processes simpler. In industrial chemical processes, particularly in petrochemical operations, separation and product refining steps are responsible for up to 30% of energy use and 30% of the capital cost. Membranes and adsorption technologies are being actively studied as alternative and partial replacement opportunities for the state-of-the-art cryogenic distillation systems. This paper provides an industrial perspective on the application of membranes in industrial petrochemical cracker operations. A gas separation performance figure of merit for propylene/propane separation for different classes of materials ranging from inorganic, carbon, polymeric, and facilitated transport membranes is also reported. An in-house–developed model provided insights into the importance of operational parameters on the overall membrane design.

Two-Dimensional Van Der Waals Materials for Spin-Orbit Torque Applications

Spin-orbit torque (SOT) provides an efficient approach to control the magnetic state and dynamics in different classes of materials. Recent years, the crossover between two-dimensional van der Waals (2D vdW) materials and SOT opens a new prospect to push SOT devices to the 2D limit. In this mini-review, we summarize the latest progress in 2D vdW materials for SOT applications, highlighting the comparison of the performance between devices with various structures. It is prospected that the large family of 2D vdW materials and numerous combinations of heterostructures will widely extend the material choices and bring new opportunities to SOT devices in the future.

Artificial intelligence simulation of water treatment using a novel bimodal micromesoporous nanocomposite

Molecular separation using nanostructured materials have attracted much attention recently for various applications. Different classes of materials have been used among which metal organic framework (MOF) and layered double hydroxide (LDH) have been recently developed due to their superior structure in separation, specifically adsorption process. In this work, we have studied removal of dye from water using a nanocomposite of MOF/LDH. The method of investigation is development of an artificial intelligence-based model for prediction of the adsorption process. The adsorption data have been obtained for removal of a dye (orange II reactive dye) from water at different conditions. The model was proposed using artificial neural network for simulation of the adsorption output which was considered to be equilibrium concentration in the solution (Ce). Indeed, the equilibrium concentration of solute was assumed as the main output in developing the model, while two inputs were postulated including the pH and adsorbent dosage. The model was built considering two hidden layers in the neural network. The validation and training steps were carried out and statistical analysis indicated excellent agreement between the simulated and measured data possessing high coefficient of determination (R2 greater than 0.999). The model revealed to be a high-performance model for simulation of dye removal using adsorption process with high accuracy.

Measuring state-of-order by dielectric response: A comprehensive review on Fröhlich entropy estimation

The so-called Fröhlich entropy is the entropy variation of a material under the application of an electric field. This quantity can be calculated, under suitable hypotheses, from the measured real part of the static dielectric function, when the imaginary part is negligible. Although Fröhlich entropy is defined for a biased sample, a straightforward physical interpretation correlates it to the state-of-order of the considered physical system in absence of field. When Fröhlich entropy is calculated from experimental results, its trend is able to give several information about the evolution in temperature of the explored compound, especially of its phase transition features. We here provide a comprehensive review of the physical systems (dipolar liquids and nematicons, organic molecular crystals, metallic nanoparticles, inorganic disordered ferroelectrics, etc.) where this approach has been exploited with the aim of evaluating their state of order and its temperature evolution. The variety of compounds where this method has been applied demonstrates that the estimation of the Fröhlich entropy can be considered a trustworthy tool for carrying out study on the state-of-order of different classes of materials. Indeed Fröhlich entropy evaluation can be considered a fruitful and reliable investigation technique which can be exploited alongside more usual experimental approaches.

(Invited) Advanced Concepts for Ultra-High Conversion Efficiency of Solar Photons into Photovoltaics and Solar Fuels Based on Semiconductor Nanostructures and Molecular Singlet Fissionajn

In order to utilize solar power for the production of solar electricity and solar fuels on a global scale, it is necessary to develop solar photon conversion systems that have an appropriate combination of very high efficiency (delivered watts/m2) and low capital cost ($/m2). One potential promising approach to attain high conversion efficiencies well above the Shockley-Queisser limit of 33% is to utilize the unique properties of semiconductor nanostructures (viz., quantum dots/rods/films) and singlet fission chromophores to control the relaxation dynamics of photogenerated carriers and photochemical excited states, respectively. The former process creates enhanced photocurrent through efficient photogenerated electron-hole pair multiplication (electron-hole pairs exist as excitons in size-quantized nanostructures), or enhanced photopotential through hot carrier transport, transfer, and extraction processes. The latter process of singlet fission generates two triplets from an excited singlet state. These fundamental dynamics in various bulk and nanoscale semiconductors and in molecular chromophores have been studied using transient absorption, photoluminescence, photocurrent and THz spectroscopy with fs to ns time resolution. The predictions that the generation of more than one electron-hole pair or exciton per absorbed photon would be an efficient process in nanostructures, and via singlet fission, have been confirmed in different classes of materials, molecules, and their architectures in photon conversion devices. Selected aspects of this work will be summarized and recent advances will be discussed, including the very remarkable and beneficial theoretical effects of combining MEG or singlet fission with solar concentration and controlling the thicknesses of the photoactive layers in a two-photon photoelectrosynthesis cell structure for solar fuels.

Finite-temperature materials modeling from the quantum nuclei to the hot electron regime

Atomistic simulations provide insights into structure-property relations on an atomic size and length scale, that are complementary to the macroscopic observables that can be obtained from experiments. Quantitative predictions, however, are usually hindered by the need to strike a balance between the accuracy of the calculation of the interatomic potential and the modelling of realistic thermodynamic conditions. Machine-learning techniques make it possible to efficiently approximate the outcome of accurate electronic-structure calculations, that can therefore be combined with extensive thermodynamic sampling. We take elemental nickel as a prototypical material, whose alloys have applications from cryogenic temperatures up to close to their melting point, and use it to demonstrate how a combination of machine-learning models of electronic properties and statistical sampling methods makes it possible to compute accurate finite-temperature properties at an affordable cost. We demonstrate the calculation of a broad array of bulk, interfacial and defect properties over a temperature range from 100 to 2500 K, modeling also, when needed, the impact of nuclear quantum fluctuations and electronic entropy. The framework we demonstrate here can be easily generalized to more complex alloys and different classes of materials.

Review on soft magnetic metal and inorganic oxide nanocomposites for power applications

• Summary of the state-of-the-art soft magnetic materials and applications in power electronics. • Characteristics of oxide-based, metal-insulator, and insulator-insulator type composites. • Overview on thermodynamics and kinetics of self-assembled nanocomposites. • Microstructure engineering of soft magnetic composites based on traditional and advanced powder processing techniques. Oxide-based nanocomposites have potential to offer much higher switching frequencies compared with state-of-the-art soft magnetic materials for applications in power electronics. However, scalable techniques for synthesizing high performance bulk oxide-based nanostructured and nanocomposite systems with superior performance compared to traditional materials are limited. This review aims at identifying existing and potential opportunities for the development of high performance nanocomposite systems through microstructure engineering specific to soft magnetic property optimization by traditional processing routes. The review begins with general introduction about soft magnetic properties of different classes of materials, followed by a detailed description of crystal structures and the underlying physics responsible for their magnetic performance. These include; soft ferrites, bulk crystalline alloys, metal-amorphous nanocomposites, and metal-oxide nanocomposites of various nature such as metal-insulator and insulator-insulator type composites. An overview on powder metallurgy techniques is provided and aspects relevant to optimizing the balance between competing requirements of high effective electrical resistivity to mitigate eddy current losses and high saturation magnetization are highlighted.

Quantifying physical parameters to predict brittle/ ductile behavior

The brittle to ductile transition (BDT) is difficult to predict without extensive fitting parameters or tuning to a particular material. Currently, predicting fracture through extensive fitting or computationally expensive algorithms is high in both cost and time required to capture the relevant deformation physics. Presented here is analysis using a comparatively high throughput analytical model to predict fracture behavior using relatively few key experimentally determined parameters: activation volume, shear stress, and activation energy. This approach could reduce the time scale to predict fracture and thus accelerate new materials discovery. The current work utilizes seminal studies to provide the inputs for validating our approach via two single crystal materials, Si and W, which both have marginal toughness at low temperatures. It is shown that knowledge of underlying deformation mechanisms (still in progress) coupled to rapid determination of physical quantities (shear stress, activation volumes, and dislocation shielding) promotes unique discovery and opportunities, including future application to polycrystalline materials and phenomena. The technique, using literature values for physical parameters, correlates well to experimental fracture behavior for these two different classes of materials, semiconductors and metals, offering new opportunities for broader study.

Nucleation site potency distributions in thermoelastic martensitic transformation in Ni43Co7Mn39Sn11 particles

The relationship between the nucleation process and thermal hysteresis width in reversible thermoelastic martensitic transformations remains unclear, particularly as the volume of transforming material decreases. Understanding the number density and nature of defects which serve as nucleation sites in this class of materials requires a quantitative analysis of nucleation site potency distributions in different classes of materials with different intrinsic barriers to nucleation. Here, we investigate the size dependence of hysteresis in microscale ${\mathrm{Ni}}_{43}{\mathrm{Co}}_{7}{\mathrm{Mn}}_{39}{\mathrm{Sn}}_{11}$ alloy particles (radius $4.4\text{--}19.0\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{m}$) during reversible martensitic transformations by collecting temperature-dependent magnetization of 126 individual alloy particles. Size-dependent hysteresis is quantified by a power law model and attributed to friction-induced energy dissipation. In samples with ideal nucleation-limited transformations, martensitic transformation temperatures on cooling decreased with decreasing particle volume due to the low probability of including relatively sparse high-energy nucleation sites. Nucleation site potency distributions are quantified as a function of thermodynamic driving force and compared against potency distributions for thermoelastic martensitic transformations in other classes of materials and for burst martensitic transformations. Across different classes of materials, as the energy barrier associated with the martensitic transformation increases, number densities of defects with sufficient potency to nucleate the transformation decrease dramatically. This finding suggests that very different kinds of defects may be responsible for nucleation of martensitic phase transformations in different material systems.

Fatigue strength of austempered ductile iron-to-steel dissimilar arc-welded joints

Nowadays, the use of different classes of materials in the same structure is increased to keep pace with innovation and high structural performances. In this context, structural components made of different materials need to be joined together and a possible solution is given by arc welding. Dissimilar welded joints must often be able to withstand fatigue loads; however, Design Standards provide fatigue strength categories only for homogeneous welded joints. The aim of the present paper is to compare the fatigue behaviour of EN-GJS-1050 austempered ductile iron-to-S355J2 steel dissimilar joints to the categories of the corresponding homogeneous steel welded joints, as suggested in International Standards and Recommendations. For this purpose, experimental fatigue tests were performed on a selection of dissimilar welded details. First, the microstructure was identified by metallographic analysis; micro-hardness measurements were collected and residual stress profiles were obtained by using the X-ray diffraction technique on a selection of joints. Misalignments were quantified for all specimens. Then, experimental fatigue tests have been performed on a number of joint geometries subject to axial or bending fatigue loadings and tested in the as-welded conditions. The fracture surfaces of the joints have been analysed to locate fatigue crack nucleation sites.