Non-crystalline Materials Research Articles

Forecast of electric transport property via two models

Temperature and synthesis condition-dependent resistivity are critical parameters for determining the electrical properties of materials. Modeling serves as a powerful tool for predicting the electrical transport characteristics of materials. The first objective of this work was to conduct a quantitative analysis of the reported metallic and insulating resistivity behaviors in double-phase materials. Using non-linear regression, both a phenomenological model and an Asym2sig asymmetric peak model were employed to quantitatively analyze the temperature-dependent resistivity. The fitting results align closely with the observed resistivity-temperature curves. The second objective of this work was to establish a method linking chemical composition (synthesis conditions) to the parameters derived from the two models, calculation on the principle of non-linear curve fitting, two numerical equations are highlighted for quantitatively analyzing chemical composition-dependent parameters. The observed effects of chemical composition on the shift in the temperature-resistive curve, which are fundamental to understanding resistivity behavior, are discussed quantitatively for the first time to our knowledge for resistive-temperature behavior. Hence, the resistivity of both crystalline and non-crystalline materials can be forecasted across various compositions and temperatures using the methods presented, even without experimental data.

Constitutive modelling for understanding stress-stretch behaviour of Lennard-Jones non-crystalline molecular Solid

Abstract Non-crystalline molecular solid materials have many scientific and engineering applications. This study develops a constitutive equation for understanding stress-stretch behaviour of non-crystalline molecular solid using Lennard-Jones (LJ) intermolecular interaction. The strain energy derived from Lennard-Jones interactions between molecules. Based on the excluded volume (spherical volume occupied by the molecules maintaining centre to centre distance with a reference molecule) and density of the molecules, strain energy density is developed. In order to relate the molecular approach with continuum approximation, the excluded volume and density are expressed as a function of strain invariants of right Cauchy-Green deformation tensor. Finally, the constitutive equation in the form of Cauchy stress tensor is developed using the present strain energy density function. The present constitutive model is used to study finite deformations of the molecular solid like uniaxial extension. We compare our theoretical results with the experimental data of flexible polyurethane foams and obtain very good agreements. The current constitutive model can predict the deformation of micro/nano engineering system components.

Irreversible, in situ, self-healing and self-glazing of geopolymers

Geopolymers are the result of the reaction of alkaline activators with reactive aluminosilicates. By dissolving these aluminosilicates and undergoing processes of polycondensation and geopolymerization, they form robust structures with distinct properties compared to other ceramics. These non-crystalline materials exhibit notable resistance to corrosion, heat, and environmental conditions, such as changes in pressure and temperature. Consequently, geopolymers, e.g., of stoichiometric composition (M2O•Al2O3•4SiO2•11H2O (or 13H2O)), find a place between cement and ceramics regarding mechanical properties. Considering the formulation of geopolymer blends, this study demonstrates that these materials have self-healing and self-glazing properties under high-temperature conditions. Through systematic experimentation and considering the specific properties of sodium-based (Na-GP) and potassium-based (K-GP) geopolymers, a combination of sodium and potassium waterglass compounds with different weight percentages were used to achieve geopolymer materials with optimum self-healing and self-glazing properties. Moreover, these samples were subjected to heat treatment under various time and temperature conditions to optimize their properties in terms of crystallization, and the best results were reported from among these variables. Based on the findings, the specific combination consisting of 75 wt% sodium waterglass and 25 wt% potassium waterglass were the best mixtures. This mixture was heated at a rate of 5 °C per minute to a temperature of 1000 °C and held isothermally for 6 h before being cooled at the same rate. As a result, an amorphous geopolymer turned into a ceramic with irreversible, self-healing, and self-glazing capabilities.

Progress, Applications, and Challenges of Amorphous Alloys: A Critical Review

Amorphous alloys, also known as metallic glasses, are a type of novel amorphous material discovered by chance. This discovery has greatly enriched the field of metal physics, spurred the rapid development of amorphous physics and materials science, and propelled amorphous physics to the forefront of condensed matter physics. As an important and challenging branch of this discipline, amorphous physics now plays a pivotal role in understanding the complexities of non-crystalline materials. Amorphous materials, characterized by their unique properties, are not only widely used in daily life and high-tech fields but also serve as model systems for studying significant scientific issues within materials science and condensed matter physics. This paper provides a comprehensive review of amorphous alloys, discussing major scientific issues and challenges in amorphous science, the formation mechanisms of these materials, their structural characteristics, and their physical and mechanical properties. Additionally, it explores the various applications of amorphous materials and forecasts future research trends, significant issues, development prospects, and directions within this vibrant field.

Structural evolution study by solid-state NMR of photopolymerizable aluminophosphosilicate hybrid materials

Aluminophosphosilicate materials of composition (mol.%) xSiO2[(Al2O3)50–(P2O5)50]100-x were prepared through sol-gel method and heat-treated yielding non-crystalline materials. The structural evolution from the hybrid to heat-treated material as a function of the SiO2 content was studied by 13C, 29Si, 31P and 27Al solid-state NMR, infrared spectroscopies, X-ray diffraction and differential scanning calorimetry (DSC). NMR analyses showed the AlPO4 formation in the matrix and heterocondensation, forming Al-O-P and P-O-Si linkages. The heat treatment promoted the formation of a more interconnected SiO2 tetrahedra network as the SiO2 content increased. Similar to the hybrid materials, the increase of SiO2 content induces the replacement of P-O-Al(IV) bonds by Si-O-Al(IV) bonds in the heat-treated materials as confirmed by 27Al NMR and 27Al{31P} REDOR data, which was also supported by Raman analysis. This sol-gel route provides a novel way to fabricate new homogeneous materials, which can be doped with rare earths and applied to new optical devices.

Exploring the Effects of the Photochromic Response and Crystallization on the Local Structure of Noncrystalline Niobium Oxide.

Niobium oxide (Nb2O5) is a versatile semiconductor material with photochromic properties. This study investigates the local structure of noncrystalline, short-range-ordered niobium oxide synthesized via a sol-gel method. X-ray atomic pair distribution function analysis unravels the structural arrangements within the noncrystalline materials at a local scale. In the following, in situ scattering and diffraction experiments elucidate the heat-induced structure transformation of the amorphous material into crystalline TT-Nb2O5 at 550 °C. In addition, the effect of photocatalytic conditions on the structure of the material was investigated by exposing the short-range-ordered and crystalline materials to ultraviolet light, resulting in a reversible color change from white to dark brown or blue. This photochromic response is due to the reversible elongation of the nearest Nb-O neighbors, as shown by local structure analysis based on in situ PDF analyses. Optical band gap calculations based on the ultraviolet-visible spectra collected for both the short-range-ordered and crystalline materials show that the band gap values reduced for the darkened materials return to their initial state after bleaching. Furthermore, electron energy loss spectroscopy reveals the reduction of Nb5+ to Nb4+ centers as a persistent effect. The study establishes a correlation between the band gap and the structure of niobium oxide, providing insights into the structure-performance relation at the atomic level.

ОПТИЧЕСКОЕ ПОГЛОЩЕНИЕ В АМОРФНОМ ГИДРОГЕНИЗИРОВАННОМ КРЕМНИИ

Despite the fact that to date there is no unified theory of noncrystalline materials, many optical and photovoltaic properties can be explained on the basis of ideas about the zone distribution of energy states in amorphous semiconductors. However, the absence of long-range order leads to a significant difference in the structure of energy bands of crystalline and disordered semiconductors.

Cleaning up Operando Battery X-Ray Diffraction with Total Scattering Computed Tomography

Operando X-ray diffraction (XRD) and total scattering investigations of battery electrode materials allow us to relate structure and electrochemical properties down to the atomic level. By studying the materials under real working conditions without allowing the materials to relax or react outside the battery, we obtain the most reliable possible structural information. Unfortunately, in most operando experiments, even when we use heavily modified cells to remove barriers to our probe radiation, the signal from the material of interest is significantly obscured by contributions from other battery components. The problems are increased when we seek to study electrode materials which either are, or become, amorphous during battery cycling: removing non-sample contributions is an essential part of pre-processing total scattering data for pair distribution function (PDF) analysis, which can reveal the local structures of non-crystalline materials.To address these problems, we have developed operando total scattering computed tomography (TSCT) as a method for obtaining clean, 5-dimensional (3-D space, time, and chemical structure) information on working batteries. The method allows us to select specific areas of the active electrode and obtain XRD and PDF information without any contributions from other components of the battery. The high-quality of the resulting data has allowed us to understand the cycling mechanisms of poorly scattering, amorphous, alloying anode materials (sodium cycling in phosphorus)[1], and complex, multi component, conversion-alloying systems (lithium cycling in bismuth vanadate)[2]. While the first example mainly uses the focusing power of TSCT to obtain the best possible data, the latter case uses the spatial resolution of the data to identify signs of a longer-term deactivation mechanism based on agglomeration of the nanoclusters of active material during repeated cycling. Further studies are currently in progress to apply the method to other difficult anode systems including silicon.[1] J. Sottmann, M. Di Michiel, H. Fjellvåg, L. Malavasi, S. Margadonna, P. Vajeeston, G.B.M. Vaughan, D.S. Wragg, Chemical Structures of Specific Sodium Ion Battery Components Determined by Operando Pair Distribution Function and X-ray Diffraction Computed Tomography, Angew. Chem. Int. Ed. 56, pp. 11385-11389, 2017[2] J. Sottmann, A. Ruud, Ø.S. Fjellvåg, G.B.M. Vaughan, M. Di Michel, H. Fjellvåg, O.I. Lebedev, P. Vajeeston, D.S. Wragg, 5D total scattering computed tomography reveals the full reaction mechanism of a bismuth vanadate lithium ion battery anode, Phys. Chem. Chem. Phys. 24, pp.27075-27085, 2022 Figure 1

Use graphene coated silica core shell particles to provide rapid, precise, and equivalent chemical composition distribution analysis for polyolefin materials by high temperature thermal gradient interaction chromatography

High temperature thermal gradient interaction chromatography (HT-TGIC) has been widely used to measure chemical composition distribution due to its applicability to separate crystalline and non-crystalline amorphous polyolefin materials. The compatibility of HT-TGIC with various detectors (infrared (IR), light scattering (LS), and viscometer) has also allowed a comprehensive analysis of molecular architecture of polyolefin and recycled plastics. The introduction of an easy-to-fabricate graphene coated onto non-porous silica particles as HT-TGIC column in 2020 showed a superior chromatographic performance over the traditional graphite column. A reduction in peak broadness (∼47 %) under identical experimental conditions was demonstrated in that research. This paper similarly uses a graphene column but with the focus on optimization of experimental parameters (concentration, and thermal cooling and heating rates etc.). Equivalent chemical composition distribution (CCD) data to that obtained by the incumbent graphite column over a wide range of polyolefins products was achieved, in addition to a shortened analysis time from 120 min down to 88 min per sample. The materials studied included semicrystalline linear low-density polyethylene (LLDPE), elastomers, terpolymers, model blends to mimic recycled plastics. The results also suggest that the elimination of substrate pores enable a better HT-TGIC separation. Coupling the ease and reproducibility of the graphene column fabrication process enables long term chromatographic robustness. This not only results in equivalent CCD data compared to the traditional graphite column but also a 27 % reduction in analysis time. These results demonstrate a substantial advancement of technology in the high throughput industrial laboratory setting where fast testing turnaround time is critical. In addition, simple fabrication with commercially available silica particles and graphene nanopowder provides a cost-effective approach to make HT-TGIC columns reproducibly.

Construction and Compensation of a Dimensional Accuracy Model of a Powder Bed via Laser Sintering.

In the laser sintering (LS) printing process, a printed part is formed by sintering layer-by-layer on the powder bed. Thus, it is necessary to consider the dimensional accuracy of the laser-sintered powder bed as an important evaluation index. In this paper, a generalized powder bed-size accuracy compensation model is proposed for non-crystalline thermoplastic polymer materials. Taking polyethersulfone (PES) material as an example, the main factors influencing powder bed dimensional accuracy during LS printing are modeled and analyzed experimentally in this study, including four important factors: laser reference deviation, temperature deviation, density deviation, and secondary sintering deviation. In this study, CX_A200 LS equipment is used for prototyping and verification, a 3D scanning method is used to measure the printed parts, and the measurement results are digitally compared and analyzed. On this basis, the relationship of each influencing factor in the proposed compensation model is determined experimentally, and the experimental results demonstrate that the proposed compensation model is approximately 95% effective in terms of correcting the deviation of powder bed dimensional accuracy.

Low-temperature anomalies and nanosized levels formation of self-organized structures in the non-crystalline solids of As(Ge)-S(Se) systems

The relationship between low-temperature anomalies of physical and chemical properties and the formation of self-organized structures in non-crystalline solids of the As(Ge)-S(Se) systems is discussed. Obtained temperature dependences for the specific heat capacity and coefficient of linear expansion in the temperature domain , detailing the linear and nonlinear contributions. The influence of the obtaining conditions of non-crystalline solids on the low-temperature behavior of physico-chemical properties and the change in the ratios of various contributions and temperature intervals is considered. The correlation and common features of the formation of self-organized structures of non-crystalline materials in the region of low temperatures and softening temperatures, manifested in the presence of nanolevels of structuring, are analyzed.

Yuya Domoto

Graphical Abstract „The most exciting thing about my research is the formation of artistic molecular structures via self-assembly … The biggest scientific advance of the last decade was that structure determination with organic microcrystals or even non-crystalline materials has become possible by microED and the crystalline-sponge method …“ Find out more about Yuya Domoto in his Introducing … Profile.

Yuya Domoto.

"The most exciting thing about my research is the formation of artistic molecular structures via self-assembly … The biggest scientific advance of the last decade was that structure determination with organic microcrystals or even non-crystalline materials has become possible by microED and the crystalline-sponge method …" Find out more about Yuya Domoto in his Introducing … Profile.

EDP2PDF: a computer program for extracting a pair distribution function from an electron diffraction pattern for the structural analysis of materials.

Pair distribution function (PDF) analysis is a powerful technique to understand atomic scale structure in materials science. Unlike X-ray diffraction (XRD)-based PDF analysis, the PDF calculated from electron diffraction patterns (EDPs) using transmission electron microscopy can provide structural information from specific locations with high spatial resolution. The present work describes a new software tool for both periodic and amorphous structures that addresses several practical challenges in calculating the PDF from EDPs. The key features of this program include accurate background subtraction using a nonlinear iterative peak-clipping algorithm and automatic conversion of various types of diffraction intensity profiles into a PDF without requiring external software. The present study also evaluates the effect of background subtraction and the elliptical distortion of EDPs on PDF profiles. The EDP2PDF software is offered as a reliable tool to analyse the atomic structure of crystalline and non-crystalline materials.

Monolithic Titanium Alkoxide Networks for Lithium-Ion Conductive All-Solid-State Electrolytes.

Reticular chemistry provides opportunities to design solid-state electrolytes (SSEs) with modular tunability. However, SSEs based on modularly designed crystalline metal-organic frameworks (MOFs) often require liquid electrolytes for interfacial contact. Monolithic glassy MOFs can have liquid processability and uniform lithium conduction, which is promising for the reticular design of SSE without liquid electrolytes. Here, we develop a generalizable strategy for the modular design of noncrystalline SSEs based on a bottom-up synthesis of glassy MOFs. We demonstrate such a strategy by linking polyethylene glycol (PEG) struts and nanosized titanium-oxo clusters into network structures termed titanium alkoxide networks (TANs). The modular design allows the incorporation of PEG linkers with different molecular weights, which give optimal chain flexibility for high ionic conductivity, and the reticular coordinative network provides a controlled degree of cross-linking that gives adequate mechanical strength. This research shows the power of reticular design in noncrystalline molecular framework materials for SSEs.

Trends and perspectives on the commercialization of bioactive glasses.

At least 25 bioactive glass (BG) medical devices have been approved for clinical use by global regulatory agencies. Diverse applications include monolithic implants, bone void fillers, dentin hypersensitivity agents, wound dressing, and cancer therapeutics. The morphology and delivery systems of bioactive glasses have evolved dramatically since the first devices based on 45S5 Bioglass®. The particle size of these devices has generally decreased with the evolution of bioactive glass technology but primarily lies in the micron size range. Morphologies have progressed from glass monoliths to granules, putties, and cements, allowing medical professionals greater flexibility and control. Compositions of these commercial materials have primarily relied on silicate-based systems with varying concentrations of sodium, calcium, and phosphorus. Furthermore, therapeutic ions have been investigated and show promise for greater control of biological stimulation of genetic processes and increased bioactivity. Some commercial products have exploited the borate and phosphate-based compositions for soft tissue repair/regeneration. Mesoporous BGs also promise anticancer therapies due to their ability to deliver drugs in combination with radiotherapy, photothermal therapy, and magnetic hyperthermia. The objective of this article is to critically discuss all clinically approved bioactive glass products. Understanding essential regulatory standards and rules for production is presented through a review of the commercialization process. The future of bioactive glasses, their promising applications, and the challenges are outlined. STATEMENT OF SIGNIFICANCE: Bioactive glasses have evolved into a wide range of products used to treat various medical conditions. They are non-equilibrium, non-crystalline materials that have been designed to induce specific biological activity. They can bond to bone and soft tissues and contribute to their regeneration. They are promising in combating pathogens and malignancies by delivering drugs, inorganic therapeutic ions, and heat for magnetic-induced hyperthermia or laser-induced phototherapy. This review addresses each bioactive glass product approved by regulatory agencies for clinical use. A review of the commercialization process is also provided with insight into critical regulatory standards and guidelines for manufacturing. Finally, a critical evaluation of the future of bioactive glass development, applications, and challenges are discussed.

Influence of Fe2O3‐FeS on the structure of iron‐containing clusters in aluminosilicate melts

AbstractIron compounds addition on the melt is a more complex issue. Uncertainties in industrial applications are caused by crystallization and depolymerization phenomena. Most of the current studies have discussed FeO and Fe2O3, ignoring the influence of FeS in the glass structure. This study designed and simulated artificial ash close to coal ash to interact with the glass melt at high temperatures. Coulomb titration, X‐ray diffraction (XRD), and Raman analyses were carried out to determine the percentage and composition of crystalline and noncrystalline materials in the glass. Samples of FeS‐Fe2O3 were subjected to the enumeration of the glass structure and quantitative calculations of the degree of polymerization. The results showed that 15‐wt% Fe2O3 promoted crystallization in the system and accelerates the depolymerization of FeS. The introduction of FeS increases the amorphous materials, and the obtained amorphous materials are Si dominated network structures and [SiO4]‐[FeO4]‐[SiO4] clusters. The network tends to change from [FeOn] and [AlO4] to [SiO4]. In addition, aluminosilicate may enter FeS particles and unreacted FeS may deposit on the aluminosilicate surface.

Cyclic Olefin Terpolymers with High Refractive Index and High Optical Transparency.

Cyclic olefin copolymer (COC) is one of the most promising optical materials; however, the brittle COC suffers from issues including a low refractive index. In this contribution, by the introduction of high refractive index comonomers including phenoxy substituted α-olefin (C4OAr), p-tolylthio substituted α-olefin (C4SAr) and carbazolyl substituted α-olefins (C4NAr, C3NAr, and C2NAr), the zirconocene mediated terpolymerization of ethylene (E) and tetracyclododecene (TCD) produces the preferred E-TCD-CnNAr (n = 2, 3, and 4) cyclic olefin terpolymers (COT) with tunable compositions (TCD: 11.5- 35.8 mol %, CnNAr: 1.2-5.0 mol %), high molecular weights and high glass transition temperatures (up to 167 °C) in high catalytic activities. Compared to the E-TCD copolymer (COC) material, these COT materials show the comparable thermal decomposition temperature (Td,5% = 437 °C), slightly higher strain at break value (up to 7.4%) and higher tensile strength (up to 60.5 MPa). In particular, these noncrystalline optical COT materials have significantly higher refractive indices of 1.550-1.569 and are more transparent (transmittance: 93-95%), relative to the COC materials, indicative of an excellent optical material.

Novel nanofibers composite based Clay: synthesis, characterization and intrinsic properties

This work focuses on the study of red brick doped with reed fibers. These properties have been studied using characterizations techniques. In this context, we used Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis on the stability configuration, chemical structures and surface properties (morphology and porosity). The synthesis protocol is followed according to the manufacturing process of bricks on an industrial scale with well-defined standards and specifications. SEM and XRD experimental results showed that doping of clay fibers could effectively increase pore size and grain size as an indication of the removal of non-crystalline cellulosic materials from the fibers. The benefits of using fiber additives in clay bricks are then confirmed from a performance and environmental point of view.

Local structural investigation of non-crystalline materials at high pressure: the case of GeO2 glass

Local structures play a crucial role in the structural polyamorphism and novel electronic properties of amorphous materials, but their accurate measurement at high pressure remains a formidable challenge. In this article, we use the local structure of network-forming GeO2 glass as an example, to present our recent approaches and advances in high-energy x-ray diffraction, high-pressure x-ray absorption fine structure, and ab initio first-principles density functional theory calculations and simulations. Although GeO2 glass is one of the best studied materials in the field of high pressure research due to its importance in glass theory and geophysical significance, there are still some long-standing puzzles, such as the existence of appreciable distinct fivefold [5]Ge coordination at low pressure and the sixfold-plus [6+]Ge coordination at ultrahigh pressure. Our work sheds light on the origin of pressure-induced polyamorphism of GeO2 glass, and the [5]Ge polyhedral units may be the dominant species in the densification mechanism of network-forming glasses from tetrahedral to octahedral amorphous structures.