Glass Formation Process Research Articles

Observation of the Pinning-Induced Crystal-Hexatic-Glass Transition in Two-Dimensional Colloidal SuspensionsSupported by the National Natural Science Foundation of China (Grant Nos. 12074275, 11704269, and 11704270), the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (Grant Nos. 20KJA150008 and 17KJB140020), and the PAPD Program of Jiangsu Higher Education Institutions.

Identification of the glass formation process in various conditions is of importance for fundamental understanding of the mechanism of glass transitions as well as for developments and applications of glassy materials. We investigate the role of pinning in driving the transformation of crystal into glass in two-dimensional colloidal suspensions of monodisperse microspheres. The pinning is produced by immobilizing a fraction of microspheres on the substrate of sample cells where the mobile microspheres sediment. Structurally, the crystal-hexatic-glass transition occurs with increasing the number fraction of pinning ρ pinning, and the orientational correlation exhibits a change from quasi-long-range to short-range order at ρ pinning = 0.02. Interestingly, the dynamics shows a non-monotonic change with increasing the fraction of pinning. This is due to the competition between the disorder that enhances the dynamics and the pinning that hinders the particle motions. Our work highlights the important role of the pinning on the colloidal glass transition, which not only provides a new strategy to prevent crystallization forming glass, but also is helpful for understanding of the vitrification in colloidal systems.

Deep glassy state dynamic data challenge glass models: Elastic models

There is increasing experimental evidence that suggests that the dynamics of glass forming liquids do not diverge at finite temperature above zero Kelvin, at the same time there has been recent progress in the development of non-diverging glass transition models. In this work we examine two non-diverging models: the elastically collective nonlinear Langevin equation theory (ECNLE) and the shoving model, both of which relate an energy barrier in the glass formation process with elastic motion at small scales. The models are evaluated in comparison with the non-diverging dynamic data obtained in the deep glassy state (very stable) for a 20-million-year-old (20 Ma) ancient amber and for a vapor deposited amorphous Teflon obtained previously. We find that although both models are in qualitative agreement with the dynamic data for the two stable glasses, they still overestimate the actual relaxation times for the deep glassy state below the nominal glass transition temperature and for conditions corresponding to the equilibrium state or in a state in which the glass relaxation times are upper bounds to the equilibrium values. • Elastic glass models (Shoving and ECNLE) are evaluated in deep glassy state • Both models show sub-T g dynamics that do not diverge above 0 K • Both models still over-estimate the equilibrium relaxation time below T g • Other processes that shorten the dynamics at temperatures approaching T K are needed

МОДИФИКАЦИЯ СИНТЕТИЧЕСКОГО СЫРЬЕВОГО МАТЕРИАЛА НА ОСНОВЕ ГИДРОКСИДА НАТРИЯ ДЛЯ ПОЛУЧЕНИЯ СТЕКЛА

The research continues the direction of intensification of glass-making processes by completely replacing soda ash in the glass batch with sodium hydroxide to obtain a well-classified intermediate two-component raw material. A method for obtaining a modified synthetic raw material (SRMm) for producing sodium-calcium-silicate glass based on quartz-containing raw material and sodium hydroxide is considered. SRMm consists of two parts, the chemical composition of one of which corresponds to the low-melting eutectic on the Na2O-SiO2 diagram, in contrast to the prototype SRM, the chemical composition of which corresponds to the chemical composition of silicate glass. The products of the synthesis of parts of quartz sand and sodium hydroxide are mixed with the rest of the components of the glass batch of alkali-silicate glasses, followed by possible agglomeration by known methods. The results of a comparative X-ray phase analysis of experimental charges, as well as heat-treated pelletized samples, show more pronounced glass formation processes in a charge based on SRMm than using the prototype. The use of experimental charges can intensify the physicochemical reactions at the stage of melting in a glass-making furnace, reduce the maximum melting temperature of glass, reduce the carryover of dust-like components of the charge and the technogenic load on the environment.

Effect of aluminum-containing raw materials on the melting of borosilicate glass for fiber

Aluminum-containing raw materials for the synthesis of aluminum-borosilicate glasses for E-glass fiber should be rationally chosen to comprehensively assess their effect on the glass melting processes. The characteristic properties of the chemical, phase, and granulometric composition of the raw materials such as metallurgical alumina, non-metallurgical alumina, disthene, and kaolin were under study. It was revealed that the type of aluminum-containing raw materials significantly influenced the rate of glass formation processes and heat consumption required for these processes. The efficiency of aluminum-containing raw materials is influenced by the following factors: the phase composition, which determines the sequence and rate of phase transformations, as well as the heat-absorbing ability of the furnace batch and glass melt. The most energy-efficient material is non-metallurgical alumina of the White Alumina brand. Using it facilitates saving energy resources for glass formation processes from 2.64% to 16.30% as compared with other types of aluminum-containing raw materials. The use of kaolin proves to be the least efficient due to the additional energy consumption for the process of destruction of the crystal structure of kaolinite, the reduced thermal conductivity of the batch, and the thermal transparency of the borosilicate glass melt.

Effect of the Additives B2O3 and P2O5 on Silicate and Glass-Formation Processes in Making Strontium Aluminosilicate Glasses

Effect of the Additives B2O3 and P2O5 on Silicate and Glass-Formation Processes in Making Strontium Aluminosilicate Glasses

Internally Stressed and Positionally Disordered Minimal Complexes Yield Glasslike Nonphononic Excitations.

Glasses, unlike their crystalline counterparts, exhibit low-frequency nonphononic excitations whose frequencies ω follow a universal D(ω)∼ω^{4} density of states. The process of glass formation generates positional disorder intertwined with mechanical frustration, posing fundamental challenges in understanding the origins of glassy nonphononic excitations. Here we suggest that minimal complexes-mechanically frustrated and positionally disordered local structures-embody the minimal physical ingredients needed to generate glasslike excitations. We investigate the individual effects of mechanical frustration and positional disorder on the vibrational spectrum of isolated minimal complexes, and demonstrate that ensembles of marginally stable minimal complexes yield D(ω)∼ω^{4}. Furthermore, glasslike excitations emerge by embedding a single minimal complex within a perfect lattice. Consequently, minimal complexes offer a conceptual framework to understand glasslike excitations from first principles, as well as a practical computational method for introducing them into solids.

Non-equilibrium cooling regulating vitrification and crystallization of Canasite-A glass-ceramics from high sodium solar silicon waste slag

This work provides an effective method for realizing both resource utilization and high-value utilization of bulk industrial solid waste. The influence of non-equilibrium cooling rates on the internal energy and amorphous structure of the precursor glass is studied to clarify the nucleation process of various crystals. A new method is proposed to control the glass formation and crystal growth process by using the cooling rate of the high-temperature melt. Research results show that the crystallization enthalpy (ΔHc) of the precursor glass decreases with decreasing cooling rates, and the NBO/T gradually decreases. When the non-equilibrium cooling rate is (k) > 10 °C/min, ΔHc is ≥ 157.05 kJ/mol and NBO/T increases to 1.09. Additionally, the glass network structure is unstable and mainly consists of Q4 structural units, which promote canasite-A crystal nucleation. The Cxonotlite:Ccanasite-A ratio increases from 1:1 to 1:5, and the crystallinity increases by 25.49%. The flexural strength of the silicon slag glass-ceramics also increases by 59.19%.

Structural Arrest and Phase Transition in Glassy Nanocellulose Colloids.

From drying blood to oil paint, the developing of a glassy phase from colloids is observed on a daily basis. Colloidal glass is solid soft matter that consists of two intertwined phases: a random packed particle network and a fluid solvent. By dispersing charged rod-like cellulose nanoparticles into a water–ethylene glycol cosolvent, here we demonstrate a new kind of colloidal glass with a high liquid crystalline order, namely, two general superstructures with nematic and cholesteric packing states are preserved and jammed inside the glass matrix. During the glass formation process, structural arrest and phase transition occur simultaneously at high particle concentrations, yielding solid-like behavior as well as a frozen liquid crystal texture that is because of caging of the charged colloids through neighboring long-ranged repulsive interactions.

Liquid-glass transition in monoatomic vanadium: A first-principles study

Monoatomic metallic glasses, successfully obtained in recent experiments, represent ideal systems to investigate the local atomic structures in glasses and glass-forming processes. By ab initio molecular dynamics we simulate the formation of a metal glass of vanadium and compute different structural, energetic, and electronic properties, including the electrical and thermal conductivities, which are compared to those of vanadium in the standard, solid-state, bcc crystal phase (obtained by adopting a slower quenching rate) and in the liquid phase too. As found for other monoatomic metallic glasses, we show that the fundamental structural process of V glass formation is represented by the tendency of V atoms to form icosahedral structures. This conclusion, together with the analysis of the electronic-charge distribution and the estimate of the electrical conductivity, suggests that the glass state of vanadium can be interpreted as a ``frozen'' (inherent) liquid configuration.

Effects of cooling rate on the atomic structure and glass formation process ofCo90Zr10metallic glass investigated by molecular dynamics simulations

In this study, the atomic structure and the glass formation process of Co90 Zr10 metallic glass alloy were studied by molecular dynamic simulation based on the embedded atom method using four different cooling rates. The average atomic volume and the potential energy of the system were observed to be strongly dependent on the cooling rate during rapid solidification, and the glass transition temperature decreased with decreasing cooling rate. The radial distribution functions and the structure factors derived from molecular dynamics simulations at 300 K agreed well with the experimental and other molecular dynamics results. The coordination numbers calculated at 300 K were consistent with the experimental results in the literature. The local structural atomic orders of the system have been characterized by Honeycutt-Andersen indices and the Voronoi tessellation method. We realized that the FCC and icosahedral shortrange order increases with decreasing cooling rate, the icosahedral clusters are predominant in the Co90 Zr10 metallic glass, and the fraction of the icosahedral polyhedra increases with decreasing cooling rate and temperature. We have seen that Co-centered Voronoi polyhedrals such as , , and play a dominant role in the development of the icosahedral order of the Co90 Zr10 alloy.

On the bulk glass formation in the ternary Pd-Ni-S system

We report on the formation of bulk metallic glasses in the ternary Pd-Ni-S system. In a large compositional range, glass formation is observed by copper mold casting with a glass forming ability of up to 2 mm in diameter for the composition Pd37Ni37S26. The best compromise of thermal stability upon heating from the as-cast state and glass forming ability was found for Pd31Ni42S27, having a critical diameter of 1.5 mm and an extension of the supercooled liquid region of 27.2 K (ΔTx = Tx – Tg). Differential scanning calorimetry and X-ray diffraction experiments were conducted in order to study the influence of the composition on the glass forming ability and thermal stability. The primary precipitating crystalline phases Ni3S2 and Pd4S are identified by in-situ high energy synchrotron X-ray scattering experiments upon heating from the glassy state as well as upon cooling from the equilibrium liquid. Finally, the origin of the bulk glass formation in this novel system is discussed regarding thermodynamics and kinetics and compared to current models for the prediction of the glass forming ability. Furthermore, the mechanical properties are investigated and discussed with respect to the rather fragile kinetic behavior. All in all, we gain new insights into the process of glass formation in this novel alloying system and give conclusions about the determining contributions for the glass forming ability and glass forming range.

Pressure Effects on the Structural Evolution of Monatomic Metallic Liquid Hafnium

Structural evolution of monatomic metallic liquid hafnium under high pressures of 0-50 GPa has been investigated by molecular dynamics (MD) simulations using the tight-binding many body potentials during rapidly solidified processes. The structural evolution and glass formation process have been analyzed by using pair distribution functions (PDF), Wendt-Abraham (RWA) parameter, Honeycutt-Andersen (HA) and Voronoi tessellation (VT) methods. When the system has been cooled with a cooling rate of 2x1013 Ks-1, the glassy states are obtained for P≤40 GPa pressures and the crystalline phase is obtained at P=50 GPa pressure. The number of face-centered cubic (fcc) and hexagonal close-packed (hcp) (fcc + hcp) type bonded pairs increase dramatically, while the number of perfect icosahedra, distorted icosahedra and body-centered cubic (bcc) type bonded pairs decreases with increasing of pressure. This is an indication that the solidification process of the system begins with nucleation in the liquid and that nucleation growth with increasing pressure continues to develop. The results show that the variation of local atomic bonded pairs is of great importance to understand the glass formation and crystallization process. However, it has been observed that the applied high pressure weakened icosahedral order and increased the fraction of other clusters in glassy hafnium at low temperatures. Furthermore, it has been observed that all glass transition temperatures (Tg), main bond types and main base clusters change with increasing pressure.

Using EXAFS data to improve atomistic structural models of glasses.

Quantitative characterization of the atomic structure of multi-component glasses is a long-standing scientific challenge. This is because in most cases no single experimental technique is capable of completely resolving all aspects of a disordered system's structure. In this situation, the most practical solution for the materials scientist is to apply multiple experimental probes offering differing degrees of insight into a material's properties. This powerful and widely adopted approach does, however, transfer the characterization challenge to the task of developing a coherent data analysis framework that can appropriately combine the diverse experimental insight into a single, data-consistent, structural model. Here, taking a terbium metaphosphate glass as an example system, it is illustrated how this can be achieved for X-ray diffraction and extended X-ray absorption fine-structure (EXAFS) spectroscopy data, using an empirical potential structure refinement approach. This methodology is based on performing a Monte Carlo simulation of the structure of a disordered material that is guided to a solution consistent with the provided experimental data, by a series of pairwise perturbation potentials operating on a classical reference potential foundation. For multi-component glasses the incorporation of EXAFS data into the resulting bulk structural models is shown to make a critical contribution that is required to properly account for the increase in local structural order that can develop in the melt-quench process of glass formation.

Comprehensive studies of the Ag+ effect on borosilicate glass ceramics containing Ag nanoparticles and Er-doped hexagonal NaYF4 nanocrystals: morphology, structure, and 2.7 μm emission

AbstractIn this work, we have performed a comprehensive investigation of the Ag+ concentration effect on the morphological, thermal, structural, and mid-infrared emission properties of novel oxyfluoride borosilicate glasses and glass ceramics containing both Ag nanoparticles and erbium-doped hexagonal NaYF4 nanocrystals. The effect of Ag+ ions on the glass forming and crystallization processes was discussed in detail by glass structural analysis. It was found that the Ag+ concentration can affect the distribution of Na+ ion and bridge oxygen in boron-rich and silicon-rich phases, which induced the transformation between BO3 triangles and BO4 tetrahedra during crystallization process. In addition, there was a turning point when the doped Ag+ ion concentration reached its solubility in the borosilicate glass. Furthermore, the enhancement of the 2.7 μm emission and the reduction of the lifetime of the 4I13/2 level were observed both in glasses and in glass ceramics, and its origin was revealed by qualitative and quantitative analyses of the Er3+-Ag nanoparticles (localized electric field enhancement) and Er3+-Er3+ (nonradiative resonance energy transfer) interactions within glasses and glass ceramics. Moreover, the high lifetime of the 4I11/2 level (2.12 ms) and the peak emission cross section in 2.7 μm (6.8×10−21 cm2) suggested that the prepared glass ceramics have promising mid-infrared laser applications.

A Complementary Study of the Chemical Behavior of Cesium Iodide in the Presence of Boron in the Condensed Phase (650°C and 400°C) Under Primary Circuit Conditions: Differential Thermal Analysis and Thermogravimetric Studies

This work is a contribution to the work performed in a paper on the understanding of the chemical reactions between cesium iodide and boron oxide in condensed phase, under conditions close to the ones prevailing in the primary circuit of a nuclear power plant in case of a severe accident. The thermal degradation of samples made from cesium iodide or cesium iodide and boron oxide mixtures has been investigated using the techniques of thermogravimetric analysis and differential thermal analysis at temperatures from 20°C to 1000°C. The boron-to-cesium molar ratio in the investigated mixture was fixed at about the value of 5 (B/Cs = 5). Apart from the dehydration of boric acid, evidence is presented for the formation of a vitreous compound at 360°C to 420°C, depending on the atmosphere composition.Carrier gas composition also seemed to influence the behavior of the precursor mixture. While under air and argon, the recorded thermograms are similar. In the presence of argon/water vapor, a specific behavior and difference on reactivity is noticed, due to the adsorption of water from the carrier gas at the beginning of the process. It was also pointed out that the addition of water or oxygen delayed the glass formation process.

Molecular-dynamics simulations of binary Pd-Si metal alloys: Glass formation, crystallisation and cluster properties

Using Quantum Sutton-Chen potentials, Molecular Dynamics was used to obtain an atomistic description of melting, glass formation and crystallisation processes for palladium metal, metallic silicon and their alloys, from PdSi to Pd5Si. Glass formation and crystallisation were investigated using different cooling rates, by analysing the radial distribution function, enthalpy, density, volume, and diffusion coefficient. As expected, glass forms at high cooling rates, while crystallisation occurs at slower rates. The glass transition temperature was estimated from the Wendt-Abraham parameter vs temperature curves and the splitting of peaks in the radial distribution function. The effect of the Pd/Si ratio on the glass transition was studied by analysing the volume change during cooling of the Pd-Si alloys. The glass forming ability was found to increase with increasing Pd concentration in the alloys. Overall, our results reveal that Quantum Sutton-Chen potentials allow good descriptions of the melting, glass transition, and crystallisation during the heating and cooling processes.

Crystal Nucleation and Growth in Undercooled Melts of Pure Zr, Binary Zr-Based and Ternary Zr-Ni-Cu Glass-Forming Alloys

Glass formation of a liquid undercooled below its melting temperature requires the complete avoidance of crystal nucleation and subsequent crystal growth. Even though they are not part of the glass formation process, a detailed knowledge of both processes involved in crystallization is mandatory to determine the glass-forming ability of metals and metallic alloys. In the present work, methods of containerless processing of drops by electrostatic and electromagnetic levitation are applied to undercool metallic melts prior to solidification. Heterogeneous nucleation on crucible walls is completely avoided giving access to large undercoolings. A freely suspended drop offers the additional benefit of showing the rapid crystallization process of an undercooled melt in situ by proper diagnostic means. As a reference, crystal nucleation and dendrite growth in the undercooled melt of pure Zr are experimentally investigated. Equivalently, binary Zr-Cu, Zr-Ni and Zr-Pd and ternary Zr-Ni-Cu alloys are studied, whose glass-forming abilities differ. The experimental results are analyzed within classical nucleation theory and models of dendrite growth. The findings give detailed knowledge about the nucleation-undercooling statistics and the growth kinetics over a large range of undercooling.

The characterisation of atomic structure and glass-forming ability of the Zr–Cu–Co metallic glasses studied by molecular dynamics simulations

In the present work, the glass formation process and structural properties of Zr50Cu50-xCox (0 ≤ x ≤ 50) bulk metallic glasses were investigated by a molecular dynamics simulation with the many body tight-binding potentials. The evolution of structure and glass formation process with temperature were discussed using the coordination number, the radial distribution functions, the volume–temperature curve, icosahedral short-range order, glass transition temperature, Voronoi analysis, Honeycutt–Andersen pair analysis technique and the distribution of bond–angles. Results indicate that adding Co causes similar responses on the nature of the Zr50Cu50-xCox (0 ≤ x ≤ 50) alloys except for higher glass transition temperature and ideal icosahedral type ordered local atomic environment. Also, the differences of the atomic radii play the key role in influencing the atomic structure of these alloys. Both Cu and Co atoms play a significant role in deciding the chemical and topological short-range orders of the Zr50Cu50-xCox ternary liquids and amorphous alloys. The glass-forming ability of these alloys is supported by the experimental observations reported in the literature up to now.

Glass transition: from interaction potential changes to the corresponding structural and relaxation responses along the path of reaching the final equilibrium

Glass transition involves a many-body interaction and relaxation process. The split of relaxation spectrum and the extremely slow dynamics bring into considerations of non-linearity and non-equilibrium. Some of our recent findings in two measurable colloidal systems are reviewed, one with a simple attractive interparticle potential and the other with a competitive (repulsive vs. attractive) inter-particle interaction. With an approach from interaction potential changes to the corresponding structural and relaxation responses, along the path of reaching the final equilibrium, we illustrate some interesting physics in glass formation process. Also, some reviews on the popular glass transition theories are made to remind readers to avoid artifacts and misinterpretations.

Accurate quantification of glass-forming ability by measuring effective volume relaxation of supercooled melt

Herein, we elucidate how to accurately quantify glass-forming ability (GFA) by measuring effective volume relaxation of supercooled melt. We propose a new parameter, denoted as κ, for representing the relaxation, which is calculated by combining temperature-dependent changes of normalized specific volume reflecting relative volume relaxation with the normalized temperature range reflecting the relative position of the C curve in a Time-Temperature-Transformation (TTT) diagram. The interrelationship between the κ parameter and critical cooling rate is elaborated by measuring V-T diagrams and TTT diagrams of Zr55Co26Al19 and Zr46Cu30.14Al8Ag8.36Be7.5 glass-forming alloys and discussed in comparison with representative GFA parameters reported up to date. These results would give us a guideline on how to precisely evaluate GFA by linking volumetric aspect to thermodynamic and kinetic aspects for glass formation and help develop customized glass-forming alloys as well as a highly precise control of glass formation process.