Promising Material Properties Research Articles

Elucidating Structural Disorder in Ultra-Thin Bi-Rich Bismuth Oxyhalide Photocatalysts.

Advancing the field of photocatalysis requires the elucidation of structural properties that underpin the photocatalytic properties of promising materials. The focus of the present study is layered, Bi-rich bismuth oxyhalides, which are widely studied for photocatalytic applications yet poorly structurally understood, due to high levels of disorder, nano-sized domains, and the large number of structurally similar compounds. By connecting insights from multiple scattering techniques, utilizing electron-, X-ray- and neutron probes, the crystal phase of the synthesized materials is allocated as layered Bi24O31X10 (X = Cl, Br), albeit with significant deviation from the reported 3Dcrystalline model. The materials comprise anisotropic platelet-shaped crystalline domains, exhibiting significant in-plane ordering in two dimensionsbut disorder and an ultra-thin morphology in the layer stacking direction. Increased synthesis pH tailored larger, more ordered crystalline domains, leading to longer excited state lifetimes determined via femtosecond transient absorption spectroscopy (fs-TAS). Although this likely contributes to improved photocatalytic properties, assessed via the photooxidation of benzylamine, increasing the overall surface area facilitated the most significant improvement in photocatalytic performance. This study, therefore, enabled both phase allocation and a nuanced discussion of the structure-property relationship for complicated, ultra-thin photocatalysts.

Wet and dry etching of ultrawide bandgap LiGa5O8 and LiGaO2

Crystalline thin films of LiGa5O8 have recently been realized through epitaxial growth via mist-chemical vapor deposition. The single crystal, spinel cubic LiGa5O8 films show promising fundamental material properties and, therefore, make LiGa5O8 a potential enabling material for power electronics. In this work, chemical resistance and etch susceptibility were investigated for the first time on crystalline LiGa5O8 thin films with various wet chemistries. It was found that LiGa5O8 is very chemically resistive to acid solutions, with no apparent etching effects observed when placed in concentrated acid solutions of HCl, H2SO4, HF, or H3PO4 at room temperature. In contrast, orthorhombic (010) LiGaO2 shows effective etching in HCl solutions at varying dilution concentrations, with etch rates measured between 8.6 [1000:1 (DI water: HCl concentration)] and 6092 nm/min (37 wt. % HCl). The inductively coupled plasma reactive ion etching (ICP-RIE) of LiGa5O8 using BCl3/Ar and CF4/Ar/O2 gas chemistries was investigated. The etching rate and surface morphology of etched surfaces were examined as a function of RIE and ICP power. Using a CF4/Ar/O2 gas chemistry with an RIE power of 75 W and an ICP power of 300 W resulted in smooth etched planar surfaces while maintaining an etch rate of ∼24.6 nm/min. Similar dry etching studies were performed for LiGaO2. It was found that the BCl3/Ar gas chemistry was better suited for LiGaO2 etching, with similar surface morphology quality being obtained after etching as prior etching when a RIE power of 15 W and an ICP power of 400 W is utilized.

Boosting Reliability

Reliability is very important in the world of electronic device design and production, particularly in applications where continuous and flawless performance is a necessity. This directs our attention to the boost converter, which forms the foundation of power electronics, renewable energy systems, and electric vehicles. However, as technology progresses, the choice of materials for these converters is a big challenge. For that, in this paper, the impact of using Silicon Carbide (SiC) devices, with their promising material properties, on the reliability of boost converters is presented. Because the results showed that more than 80% of boost converter failures are caused by semiconductors, the use of SiC materials is assessed by determining its reliability using MIL-HDBK-217 standard. In addition, a comparative study with the use of traditional Silicon (Si) is conducted. The results showed that the failure rate of boost converters based on SiC devices reduced from 8.335 failure/10-6h to 6.243 failure/10-6h. This notable shift in failure rates establishes SiC as a pivotal material in the evolution of boost converter technology, offering a compelling solution to address the persistent challenges associated with semiconductor-related failures.

Manipulating the phase stability of a halide perovskite, CH3NH3PbI3 by high-pressure cycling

Methylammonium lead iodide perovskite, CH3NH3PbI3 (MAPbI3) is a highly promising photovoltaic material, whose structural and electronic properties are very sensitive to applied stresses. Here, we show that the phase stability of a MAPbI3 crystal can be controlled by structural defects and strains. We synthesized a single crystal of MAPbI3 and measured its electrical properties across two successive structural phase transitions under applied pressure up to 4–9 GPa under multiple high-pressure cycling. We revealed three types of effects of this high-pressure treatment. (i) An increasing the level of defects and strains in the crystal greatly delays the first reconstructive phase transition, conserving the ambient-pressure tetragonal phase up to a record pressure of ∼1.4 GPa, much higher compared to its typical stability range of up to 0.3–0.5 GPa only. (ii) A time exposure of the crystal at a fixed pressure corresponding to the beginning of the second phase transition to a “destabilized” structure eliminated some of defects and strains; it down-shifted the phase boundaries back. (iii) A recrystallization of the sample after pressure-induced amorphization enhanced its structural stability against amorphization upon subsequent pressurization cycle. We proposed that the most abundant defects and strains, which could appear in the pressure-cycled MAPbI3 crystals, were related to migration of iodine atoms from their regular sites to the MA interstices. Temperature-dependent photoluminescence measurements indicated that the sample recovered after the high-pressure cycling crystallized back into the initial tetragonal crystal structure. Whereas, its stability range expanded toward lower temperatures by 20 K and a band gap slightly increased, from 1.59 to 1.625 eV (at 290 K). Using this organic-inorganic perovskite as an example, we show how the phase stability of such materials can be manipulated by creation and elimination of structural defects and local strains.

Composite Liquid Biofuels for Power Plants and Engines: Review

The problems of environmental pollution caused by the operation of power plants and engines motivate researchers to develop new biofuels. The environmental aspect of composite biofuels appears to have great potential because of the carbon neutrality of plant raw materials. This study analyzes recent advances in the production of biofuels and their application. The research findings on the properties of promising plant raw materials and their derivatives have been systematized. The most important stages (spraying, ignition, and combustion) of using biofuels and mixtures based on them in internal combustion engines have been analyzed. A separate section reviews the findings on the environmental aspect of using new fuel compositions. Most studies show great prospects for involving bio-components in the development of composite fuels. The real issue is to adjust existing engines and plants to non-conventional fuel mixtures. Another big problem is the increased viscosity and density of biofuels and oils, as well as the ambiguous effect of additives on burnout completeness and emissions. The impact of the new kinds of fuels on the condition of components and parts of engines, corrosion, and wear remains understudied. The interrelation of industrial process stages (from feedstock to an engine and a plant) has not been closely examined for composite liquid fuels. It is important to organize the available data and develop unified and adaptive technologies. Within the framework of this review work, scientific approaches to solving the above problems were considered and systematized.

Perovskite-Based X-ray Detectors.

X-ray detection has widespread applications in medical diagnosis, non-destructive industrial radiography and safety inspection, and especially, medical diagnosis realized by medical X-ray detectors is presenting an increasing demand. Perovskite materials are excellent candidates for high-energy radiation detection based on their promising material properties such as excellent carrier transport capability and high effective atomic number. In this review paper, we introduce X-ray detectors using all kinds of halide perovskite materials along with various crystal structures and discuss their device performance in detail. Single-crystal perovskite was first fabricated as an active material for X-ray detectors, having excellent performance under X-ray illumination due to its superior photoelectric properties of X-ray attenuation with μm thickness. The X-ray detector based on inorganic perovskite shows good environmental stability and high X-ray sensitivity. Owing to anisotropic carrier transport capability, two-dimensional layered perovskites with a preferred orientation parallel to the substrate can effectively suppress the dark current of the device despite poor light response to X-rays, resulting in lower sensitivity for the device. Double perovskite applied for X-ray detectors shows better attenuation of X-rays due to the introduction of high-atomic-numbered elements. Additionally, its stable crystal structure can effectively lower the dark current of X-ray detectors. Environmentally friendly lead-free perovskite exhibits potential application in X-ray detectors by virtue of its high attenuation of X-rays. In the last section, we specifically introduce the up-scaling process technology for fabricating large-area and thick perovskite films for X-ray detectors, which is critical for the commercialization and mass production of perovskite-based X-ray detectors.

Practical synthesis of 1,3-benzoazaphosphole analogues.

Despite the promising pharmacological activity and material properties of five-membered heterocyclic compounds containing phosphorus and nitrogen, synthetic examples of them have been rather limited due to the instability of phosphorus toward air and water. In this study, 1,3-benzoazaphosphol analogues were selected as target molecules, and various synthetic routes were examined to establish a fundamental technology for the introduction of phosphorus groups into aromatic rings and formation of five-membered rings containing phosphorus and nitrogen by cyclization. As a result, we found that 2-aminophenyl(phenyl)phosphine is an extremely promising synthetic intermediate with high stability and easy handling. Furthermore, 2-methyl-3-phenyl-2,3-dihydro-1H-benzo[d][1,3]azaphosphole and 3-phenyl-2,3-dihydro-1H-benzo[d][1,3]azaphosphole-2-thione as synthetically useful 1,3-benzoazaphosphol analogues were successfully synthesized by using 2-aminophenyl(phenyl)phosphine as a key intermediate.

Исследование относительной восприимчивости изотопов кремния к потоку тепловых нейтронов

To solve problems related to the study of the possibility of changing the properties of promising semiconductor materials, the mechanisms of interaction of neutron radiation with silicon isotopes are investigated. The study of this semiconductor material is especially relevant because of its widespread use in modern semiconductor technologies for the construction integrated circuits. The types of interactions of neutron radiation with matter, the main mechanisms of formation of crystal lattice defects under the influence of thermal neutrons are investigated. Random processes of interaction of thermal neutron flux with three isotopes of silicon 28Si, 29Si and 30Si are simulated. The isotope 29Si, which is most susceptible to elastic interactions, has been determined. In the case of reactions (n, γ), the isotope 28Si was the most sensitive.

Recent Advances in the Nanomaterials, Design, Fabrication Approaches of Thermoelectric Nanogenerators for Various Applications

AbstractThermoelectric nanogenerators (TENGs) are promising sustainable energy devices that utilize thermoelectric (TE) effect of nanomaterials to convert a temperature gradient into electrical energy. Compared to bulk thermoelectric generators (TEGs) that are commercially available, TENGs are more flexible and power‐dense, owing to their tuneable nanostructures. Hence, smaller TENGs are better suited for small form‐factor applications like wearable electronics, internet of things (IoT) devices, and self‐powered sensors. However, the higher complexity and cost of TENGs than TEGs inhibit their widespread adoption. This review appraises the latest advances in TENG materials, design, and fabrication in optimizing the performance of TENGs, making TENGs more viable for real‐world applications. More precisely, this work examines how nanostructure engineering, nanomaterial compositing, and post‐synthesis treatment approaches have enhanced the TE properties of common and promising TE materials, including tellurides, selenides, metal oxides, metal alloys, silicon, carbon nanomaterials, and organic compounds. Given that the TE material is a key component in TENGs, this review highlights how to optimize other vital parameters, including the TENG configuration, contact interface, form factor, heat sink use, and folded shape for specific applications. Lastly, critical attributes of TENGs used in wearable electronics, sensors, implantable electronics, solar energy conversion, and waste heat recovery are analyzed.

Evidence on the social, economic, and environmental impact of interventions that facilitate bamboo industry development for sustainable livelihoods: a systematic map protocol

BackgroundBamboo has been identified as a potential instrument for socioeconomic development due to its fast growth, perceived environmental benefits, promising material properties, myriad applications, and relative underdevelopment as a global industrial product. Many projects and interventions have been carried out that aim to utilize bamboo’s social and environmental potential in development. However, critical evaluations that demonstrate this effect using real-world evidence and outcomes are rare, and existing case studies have not been collated and analyzed in a systematic way. The proposed systematic map aims to summarize and evaluate evidence on the social, economic, and environmental impact of bamboo industry development initiatives on beneficiary communities and ecosystems, and to identify priority areas for future funding and research.MethodsIn the proposed systematic map, we will collect and thematically categorize evidence on the social, environmental, and economic impact of bamboo development implementations, identifying themes, research gaps, and critical success factors. Literature discussing this type of intervention is published by researchers, organizations, and governments in academic journals, institutional reports, and program evaluations describing various socio-economic and environmental outcomes, impacts and metrics for success. Search sources for this systematic map therefore include bibliographic databases, institutional websites, web-based search engines, and expert consultation. Targeted search strings will be used to identify relevant texts in a two-step review process comprising an abstract and a full-text screening process. Sources describing interventions with a primary aim of bamboo industry development for social benefit that concluded between 1990 and 2021 will be sought. Metadata coded from these texts will be reviewed, categorized, and checked by two reviewers. Reviewers will be checked for consistency on batches of 30 articles using the Kappa interrater reliability test with a goal of a Kappa coefficient of 0.9. Metadata will be coded into different categories including outcomes and impacts using NVivo. Results of both quantitative and qualitative data analysis will be summarized in a searchable online database. Themes will be synthesized and explored in a narrative review and using simple logic models demonstrating theories of change for eligible case studies.

Research of electrical properties of dielectric elastomers

The properties of promising dielectric materials, in particular, elastomers used in precision movement mechanisms as a working body, are considered. The influence of the dielectric constant on the deformation of the material under the influence of an electric field is analyzed. It is experimentally established that with an increase in the filler concentration, the dielectric constant of the material increases. Keywords: dielectric elastomer, actuator, precision movement mechanism, dielectric constant, deformation, external electric field, barium titanate. ambazinenkov@bmstu.ru

STUDY OF THE EFFECT OF ZCO CERAMIC PHASE COMPOSITION ON OPTICAL AND THERMOPHYSICAL PROPERTIES

The work is devoted to the study of optical and thermophysical properties of promising materials for nuclear power of a new generation - inert matrices of nuclear dispersed fuel based on ZrO2 – CeO2 (ZCO) doped with Y2O3. Interest in this class of materials is due to great prospects in the field of replacing the traditional type of nuclear fuel with uranium-free dispersed nuclear fuel, which is based on a technological solution using plutonium as a fissile element, placed in a dispersed inert matrix based on oxide or nitride ceramics. The purpose of this work is to study the effect of doping of ZCO ceramics with Y2O3 on the optical and heat-conducting properties. During the study, it was found that an increase in the concentration of the Y2O3 dopant leads to the formation of a highly ordered CeZrO4 phase, the presence of which leads to the appearance of an additional absorption band in the region of 550 – 650 nm, as well as a decrease in the transmission value in the region of 400 – 700 nm. To evaluate the results obtained, the methods of optical UV spectroscopy and heat flux determination were applied. It has been found that doping with Y2O3 leads to the formation of a highly ordered CeZrO4 phase, the formation of which leads to the appearance of additional spectral absorption lines, as well as a shift in the band gap to the region of low energies. During analysis of the thermophysical parameters, it was found that a change in the phase composition leads to an increase in the thermal conductivity coefficient by more than 40 – 60 %.

Advances and trends in microbial production of polyhydroxyalkanoates and their building blocks.

With the rapid development of synthetic biology, a variety of biopolymers can be obtained by recombinant microorganisms. Polyhydroxyalkanoates (PHA) is one of the most popular one with promising material properties, such as biodegradability and biocompatibility against the petrol-based plastics. This study reviews the recent studies focusing on the microbial synthesis of PHA, including chassis engineering, pathways engineering for various substrates utilization and PHA monomer synthesis, and PHA synthase modification. In particular, advances in metabolic engineering of dominant workhorses, for example Halomonas, Ralstonia eutropha, Escherichia coli and Pseudomonas, with outstanding PHA accumulation capability, were summarized and discussed, providing a full landscape of diverse PHA biosynthesis. Meanwhile, we also introduced the recent efforts focusing on structural analysis and mutagenesis of PHA synthase, which significantly determines the polymerization activity of varied monomer structures and PHA molecular weight. Besides, perspectives and solutions were thus proposed for achieving scale-up PHA of low cost with customized material property in the coming future.

Avalanche and Short Circuit Robustness of Vertical GaN FET [Expert View

GaN power semiconductor devices have been the recent focus of intense development efforts due to the promising material properties of GaN for next-generation power electronics applications. For power switching and rectifying applications, the ruggedness in breakdown is a critical requirement as addition of snubber circuits reduce the performance and efficiency of the system. Lateral GaN high-electron mobility transistors (HEMTs) have been commercialized up to 900 V class recently, but they lack avalanche capabilities. Vertical GaN transistors demonstrate several advantages over lateral GaN HEMT: 1) higher breakdown voltage (BV) and current for a given chip area, 2) higher reliability, 3) easier thermal management, 4) avalanche capabilities, and 5) short-circuit robustness.

Antibacterial and Osteogenic Properties of Ag Nanoparticles and Ag/TiO2 Nanostructures Prepared by Atomic Layer Deposition.

The combination of titania nanofilms and silver nanoparticles (NPs) is a very promising material, with antibacterial and osseointegration-induced properties for titanium implant coatings. In this work, we successfully prepared TiO2 nanolayer/Ag NP structures on titanium disks using atomic layer deposition (ALD). The samples were studied by scanning electron microscopy (SEM), X-ray diffraction, X-ray photoelectron spectroscopy (XPS), contact angle measurements, and SEM-EDS. Antibacterial activity was tested against Staphylococcus aureus. The in vitro cytological response of MG-63 osteosarcoma and human fetal mesenchymal stem cells (FetMSCs) was examined using SEM study of their morphology, MTT test of viability and differentiation using alkaline phosphatase and osteopontin with and without medium-induced differentiation in the osteogenic direction. The samples with TiO2 nanolayers, Ag NPs, and a TiO2/Ag combination showed high antibacterial activity, differentiation in the osteogenic direction, and non-cytotoxicity. The medium for differentiation significantly improved osteogenic differentiation, but the ALD coatings also stimulated differentiation in the absence of the medium. The TiO2/Ag samples showed the best antibacterial ability and differentiation in the osteogenic direction, indicating the success of the combining of TiO2 and Ag to produce a multifunctional biocompatible and bactericidal material.

Targeted Synthesis of the Type-A Particle Substructure from Enzymatically Produced Eumelanin.

Eumelanin exhibits a defined supramolecular buildup that is deprived of at least three distinct particle species. To enable the full potential of its promising material properties, access to all particle types is crucial. In this work, the first protocol for the synthesis of the intermediate type-A particles in pure and stable dispersion form is described. It is found that aggregation of type-A particles into the larger type-B variant can be inhibited by a strict pH control during the synthesis. The exact influence of pH on the supramolecular buildup is investigated via a combination of time-resolved light scattering, electron microscopy, and UV–vis spectroscopy. It is observed that a rapid buildup of type-B particles occurs without pH control and is generally dominant at lower pH values. At pH values above 6.2 however, type-A particles are gained, and no further aggregation occurs. Even more, lowering the pH of such a stable type-A dispersion at a later stage lifts the inhibition and again leads to the formation of larger particle species. The results confirm that it is easily possible to halt the aggregation of eumelanin substructures and to access them in the form of a stable dispersion. Moreover, a profound additional understanding of the supramolecular buildup is gained by the in-depth investigation of the pH influence.

Results of studies of thermophysical properties of promising materials

Results of studies of thermophysical properties of promising materials

Waste Reutilization in Polymeric Membrane Fabrication: A New Direction in Membranes for Separation.

In parallel to the rapid growth in economic and social activities, there has been an undesirable increase in environmental degradation due to the massively produced and disposed waste. The need to manage waste in a more innovative manner has become an urgent matter. In response to the call for circular economy, some solid wastes can offer plenty of opportunities to be reutilized as raw materials for the fabrication of functional, high-value products. In the context of solid waste-derived polymeric membrane development, this strategy can pave a way to reduce the consumption of conventional feedstock for the production of synthetic polymers and simultaneously to dampen the negative environmental impacts resulting from the improper management of these solid wastes. The review aims to offer a platform for overviewing the potentials of reutilizing solid waste in liquid separation membrane fabrication by covering the important aspects, including waste pretreatment and raw material extraction, membrane fabrication and characterizations, as well as the separation performance evaluation of the resultant membranes. Three major types of waste-derived polymeric raw materials, namely keratin, cellulose, and plastics, are discussed based on the waste origins, limitations in the waste processing, and their conversion into polymeric membranes. With the promising material properties and viability of processing facilities, recycling and reutilization of waste resources for membrane fabrication are deemed to be a promising strategy that can bring about huge benefits in multiple ways, especially to make a step closer to sustainable and green membrane production.

Hybrid Devices by Selective and Conformal Deposition of PtSe2 at Low Temperatures

Abstract2D materials display very promising intrinsic material properties, with multiple applications in electronics, photonics, and sensing. In particular layered platinum diselenide has shown high potential due to its layer‐dependent tunable bandgap, low‐temperature growth, and high environmental stability. Here, the conformal and area selective (AS) low‐temperature growth of layered PtSe2 is presented defining a new paradigm for 2D material integration. The thermally‐assisted conversion of platinum which is deposited by AS atomic layer deposition to PtSe2 is demonstrated on various substrates with a distinct 3D topography. Further the viability of the approach is presented by successful on‐chip integration of hybrid semiconductor devices, namely by the manufacture of a highly sensitive ammonia sensors channel with 3D topography and fully integrated infrared‐photodetectors on silicon photonics waveguides. The presented methodologies of conformal and AS growth therefore lay the foundation for new design routes for the synthesis of more complex hybrid structures with 2D materials.

Dispersion Diagram of Trigonal Piezoelectric Phononic Structures with Langasite Inclusions

The dispersion relation of elastic Bloch waves in 1-3 piezoelectric phononic structures (PPnSs) with Langasite (La3Ga5SiO14) inclusions in a polymeric matrix is reported. Langasite presents promising material properties, for instance good temperature behaviour, high piezoelectric coupling, low acoustic loss and high quality factor. Furthermore, Langasite belongs to the point group 32 and has a trigonal structure. Thus, the 2-D bulk wave propagation in periodic systems with Langasite inclusions cannot be decoupled into XY and Z modes. The improved plane wave expansion (IPWE) is used to obtain the dispersion diagram of the bulk Bloch waves in 1-3 PPnSs considering the classical elasticity theory and D3 symmetry. Full band gaps are obtained for a broad range of frequency. The piezoelectricity enhances significantly the band gap widths and opens up a narrow band gap in lower frequencies for a filling fraction of 0.5. This study should be useful for surface acoustic wave (SAW) filter and 1-3 piezocomposite transducer design using PPnSs with Langasite.