Glass Behavior Research Articles

The Harmonic and Gaussian Approximations in the Potential Energy Landscape Formalism for Quantum Liquids.

The potential energy landscape (PEL) formalism has been used in the past to describe the behavior of classical low-temperature liquids and glasses. Here, we extend the PEL formalism to describe the behavior of liquids and glasses that obey quantum mechanics. In particular, we focus on the (i) harmonic and (ii) Gaussian approximations of the PEL, which have been commonly used to describe classical systems, and show how these approximations can be applied to quantum liquids/glasses. Contrary to the case of classical liquids/glasses, the PEL of quantum liquids is temperature-dependent, and hence, the main expressions resulting from approximations (i) and (ii) depend on the nature (classical vs quantum) of the system. The resulting theoretical expressions from the PEL formalism are compared with results from path-integral Monte Carlo (PIMC) simulations of a monatomic model liquid. In the PIMC simulations, every atom of the quantum liquid is represented by a ring-polymer. Our PIMC simulations show that at the local minima of the PEL (inherent structures, or IS), sampled over a wide range of temperatures and volumes, the ring-polymers are collapsed. This considerably facilitates the description of quantum liquids using the PEL formalism. Specifically, the normal modes of the ring-polymer system/quantum liquid at an IS can be calculated analytically if the normal modes of the classical liquid counterpart are known (as obtained, e.g., from classical MC or molecular dynamics simulations of the corresponding atomic liquid).

Revelation of the high hardness and spin glass behavior in the novel magnetic material CrFeB

Ternary transition metal borides (TTMBs) will break materials application limitation in harsh service environments, owing to their structure versatility and high component tunable ability. Herein, we reported a solid solution boride CrFeB synthesized by high pressure and high temperature method. CrFeB yields an asymptotic hardness of 14.2 GPa and thermal stability temperature is up to 1250 K. DC magnetic susceptibility measurements revealed that there is a separation between zero-field cooled and field cooled curve at around 5 K, which indicated the spin glass behavior for CrFeB. Temperature dependence AC susceptibility analysis gives further evidence that the freezing temperature increases with frequency following Vogel-Fulcher law. On the basis of XPS results and first-principle calculations, we speculate that the complex magnetic behaviors may derive from the short-range magnetic exchange of same occupation sites two metal atoms. Cr and Fe atoms tend to have opposite magnetic moments in these short-range exchange behaviors. The intrinsic magnetic disorder and short-range frustration lead to spin random freezing of CrFeB at low temperatures, which conforms to typical spin glass characteristics. These results will contribute to understanding the complex magnetism behavior of CrFeB and provides a new idea to design multifunctional TTMBs.

Pre- and post-fire behaviour of glass concrete from wet packing density perspective

Recycled glass can be ground into different particle sizes to partially replace cement or aggregates, which is important for developing sustainable concrete production. In this study, a total of 16 concrete mixes containing glass powder (GP), silica fume (SF) and glass sand (GS) were designed to investigate the fresh and harden material properties at ambient temperature, heat transfer mechanism and temperature development, mass loss, apparent change of surface texture as well as residual compressive strength and elastic modulus after exposure to elevated temperatures (400–1000 °C). Results show that glass concrete possesses larger slump flow and suffers less mass loss which are believed to be caused by the improved wet packing density (WPD) and the existence of more abundant excess water. Besides, replacing cement partially with GP up to 15% and/or SF up to 10% would enhance the compressive strength by 11.6% and 4.7% respectively and elastic modulus by 4.5% and 5.3% of concrete. At elevated temperatures, the core temperature of concrete containing GP was lower, indicating that GP could provide an effective solution in improving the concrete's heat-insulation capacity due to the enhanced WPD. After exposure to 400, 600, 800 and 1000 °C, the incorporation of glass in concrete was effective in enhancing the residual compressive strength by maximum 15.2%, 38.3%, 9.1% and 37.5% and elastic modulus by maximum 7.5%, 17.3%, 19.4% and 19.5%, respectively due to the enhanced WPD and re-solidification of GP/GS in its molten state that strengthened the interface transition zone.

Tailoring rejuvenation behavior of Zr-based metallic glass upon deep cryogenic cycling treatment

The rejuvenation behavior of a Zr55Cu30Ni5Al10 (at.%) metallic glass upon deep cryogenic cycling treatment was investigated. The sample was rejuvenated to a larger extent with increasing cyclic number, resulting in a higher enthalpy of relaxation and a lower density. The rejuvenation seems to be saturated after 200 cycles, which may originate from the limited content of free volume in the amorphous structure. The sample subjected to a higher cyclic number showed a lower hardness and better plasticity due to a larger shear transformation zone (STZ) volume. In this case, a lower shear plane formation energy facilitates the generation of multiple shear bands. Furthermore, it is found that the content of free volume has linear relationship with the plastic strain and the STZ volume. The results from molecular dynamics simulation also demonstrates that the atomic volume saturates with a higher degree of rejuvenation at a higher cooling rate of the simulated sample.

Predicting spectroscopic properties of quaternary phosphate laser glasses

AbstractQuantitative composition‐structure‐property (C–S–P) relationship analysis is a promising approach to correlate structural features with properties of glasses that have complex structures and lack long‐range order. In this study, the structure and spectroscopic properties of two typical P2O5‐MO‐K2O‐Al2O3 (M = Mg, Ba) quaternary phosphate laser glasses doped with Nd3+ ions are calculated and predicted. By using the nearest‐neighboring congruently melting compounds in the phase diagram as “component and structural motifs”, correlations with properties and insights on glass behaviors can be obtained. Two key physical properties and five spectroscopic properties are predicted and verified with an error of less than 5% and 10%, respectively. Furthermore, two C–S–P databases with more than 1000 glass compositions are established for designing and optimizing new laser glasses. The results show that this approach not only gets rid of the traditional qualitative research method which relies on empirical formulas, but also promotes the quantitative calculation and predictable design of glass research.

Luminescent CdS quantum dot-embedded glass for W-LED lighting and X-ray imaging

Quasi-zero-dimensional quantum dots (QDs) have garnered significant attention owing to their distinct structural attributes, quantum confinement behaviors, optoelectronic characteristics, etc. Regrettably, their susceptibility to stability poses a challenge. In this context, leveraging rational component regulation and crystallization process optimization strategies, we presented the successful preparation of CdS QDs silicate glass through the amalgamation of melt-quenching and controlled crystallization. The optical and morphological analysis substantiated the accomplishment of in-situ precipitation of CdS QDs within the glass matrix, with grain sizes <20 nm. Integrating CdS QDs into an inorganic glass matrix remarkably augmented its fluorescence thermal stability, enabling the preservation of 85.1 % of the room-temperature luminescent intensity even at an elevated temperature of 150 °C. Moreover, the encapsulated W-LED device by near-UV LED chip, CdS QDs glass, and BaMgAl10O17:Eu2+ phosphor exhibited a warm white-light emission characterized by suitable chromaticity coordinates (0.3741, 0.3452) and a notably high color rendering index (CRI = 93). Ultimately, the radioluminescence behavior of CdS QDs glass was unveiled by utilizing it as the scintillator wafer in an X-ray imaging system, which clearly demonstrated the structure of spring encapsulated within an opaque capsule. In a nutshell, these demonstrations unequivocally emphasize the substantial potential merits of CdS QDs glass, particularly in the domains of long-term W-LED lighting and X-ray imaging applications.

Inherent correlation between mechanical and structural heterogeneity in metallic glasses

Comprehending the physical and mechanical behavior of metallic glasses (MGs) from the perspective of local structural heterogeneity has long been one of the most active research topics in the field of metastable materials. In this study, nanoindentation simulations were employed to study the local elastic behavior of the classical CuZr MGs and discuss the inherent correlation between mechanical and structural heterogeneity. The results show that the mechanical response is governed by the heterogeneity of Voronoi clusters in terms of variety, quantity, and connection mode within the range of indentation. A critical dimension to distinguish nanoscale heterogeneity has been found to be around 30 nm, below which the local mechanical responses are directly correlated to the distribution of characteristic clusters and represent obvious spatial heterogeneity. All these results are expected to bridge the gap between the macro-scale isotropy and the nanoscale heterogeneity of MGs.

Highly efficient catalytic performance and self-renewing behavior of Fe-based glass induced by pulsed laser

FeSiB metallic glass using pulsed laser processing is proved to show excellent catalytic performance in wastewater treatment for the first time by decolorizing and mineralizing reactive red 195. Pulsed laser can effectively improve the thermodynamic properties, surface photothermal conversion and hydrophilicity of catalyst. Compared with homogeneous FeSiB catalyst, heterogeneity α-Fe/FeSiB exhibits a high k value, strong TOC removal rate and low activation energy. Theoretical calculations indicate that the excellent catalytic performance of heterogeneity catalyst is attributed to its unique nanoscale biphasic disorder structure, resulting the energy barrier of the rate-determining-steps of the conversion of S2O82− to SO4−• is reduced from 2.20 to 1.52 eV. The reusability test of heterogeneity catalyst also shows that the abnormal recovery phenomenon of decolorization efficiency at the 19th cycle owing to its unique self-renewing. This study reveals that a nanoscale biphasic disorder structure is a new strategy for obtaining high catalytic rate and durability.

Accurate and Transferable Machine Learning Potential for Molecular Dynamics Simulation of Sodium Silicate Glasses.

An accurate and transferable machine learning (ML) potential for the simulation of binary sodium silicate glasses over a wide range of compositions (from 0 to 50% Na2O) was developed. The potential energy surface is approximated by the sum of atomic energy contributions mapped by a neural network algorithm from the local geometry comprising information on atomic distances and angles with neighboring atoms using the DeePMD code [Wang, H. Comput. Phys. Commun. 2018, 228, 178-184]. Our model was trained on a large data set of total energies and atomic forces computed at the density functional theory level on structures extracted from classical molecular dynamics (MD) simulations performed at several temperatures from 300 to 3000 K. This allows for the generation of a robust and transferable ML potential applicable over the full compositional range of glass formability at different temperatures that outperforms the empirical potentials available in the literature in reproducing structures and properties such as bond angle distribution, total distribution functions, and vibrational density of state. The generality of the approach enables the future training of a potential with other or more elements allowing for simulations of structures, properties, and behavior of ternary and multicomponent oxide glasses with nearly ab initio accuracy at a fraction of the computational cost.

Atomistic origins of deformation-induced structural anisotropy in metaphosphate glasses and its influence on mechanical properties

Glasses are generally isotropic. However, structural anisotropy can be induced through processing. Here, molecular dynamics simulations were used to study the deformation behavior of metaphosphate glasses and the atomistic origins of the deformation-induced structural anisotropy. The anisotropy observed in the metaphosphate glasses originates from a preferred orientation of the tetrahedral units at both short- and medium-range, depending on the loading mode. The mechanical behavior of the glasses showed that the Young’s modulus of the anisotropic glasses is lower than that of pristine glasses. Pre-deformed glass shows a clear directional dependence with respect to the axis of the pre-deformation. In general, the Young’s moduli of the pre-deformed glasses are lower than those of pristine glasses. These findings provide insights into the origin of deformation-induced anisotropy in metaphosphate glasses and its influence on their mechanical properties, thus providing important insight for the rational design of oxide glasses with tailored material properties.

Electrical, optical, and electrochemical performances of phosphate-glasses-doped with ZnO and CuO and their composite with polyaniline

Phosphate-based glasses (PBG) with appropriate doping agents have been used as solid electrolytes in solid-state ionic devices. Therefore, more light was shed on the electrical, optical, and electrochemical behavior of the phosphate-based glasses (PBG), containing ZnO or CuO in the absence and existence of conductive polyaniline (PANI), since no publications are available concerning this work. The glass samples were prepared by the rapid quenching method, then mixing phosphate glass and polyaniline (PANI) with metal oxide (ZnO, CuO). They were characterized by different techniques; diffuse reflectance spectrophotometer (DRS), broadband dielectric spectrometer (BDS), cyclic voltammetry (CV), and charge–discharge techniques. In the DRS study, the direct and indirect band gap were calculated from Tauc’s relationship where CuO-doped glasses have higher values than ZnO-doped glasses. In the BDS study, the permittivity of all glass compositions decreased while AC conductivity increased with increasing frequency. AC conductivity of PBG doped with metal oxides and mixed with PANI exhibited semiconducting features (6.8 × 10–4 S/cm). Further, these composites exhibited lower loss tangent (0.11), and giant permittivity (186,000) compared to the pure PBG. Also, the electrochemical study exhibited that the composite with 7% CuO content has the highest specific capacitance value (82.3 F/g at 1.0 A/g) which increased to about 113% of its first cycle and then decreased to about 55% after 2500 cycles and finally increased again to 77% after 4500 cycles, indicating its good stability. The combination of optical, electrical, and electrochemical features of these composites suggests their use for energy generation and storage devices.

Effect of MoO3/WO3 modulation on high-temperature wettability and crystallization behavior of glass and its application in solar cell

The role of glass in the metallization contact of crystalline silicon solar cells is crucial. Numerous studies have been conducted to investigate the reaction between the main components in glass and SiNx antireflection layer during sintering. Additionally, the low content component in glass plays an indispensable role in etching and wetting silicon base. The present study investigated the impact of ionic radius on glass properties through manipulation of the elemental composition of transition metals Mo and W. The results indicated a significant decrease in the characteristic temperature point of glass and an increase in wettability after the addition of MoO3 and WO3. Furthermore, the thermal expansion of glass was observed to increase with higher WO3 content. Screen printing for the preparation of silver electrodes revealed that glass-silver pastes had optimal printing properties. When the quality ratio of MoO3 and WO3 was 7:3, it effectively enhanced the precipitation of Bi2WO6 and Pb7.90Mo0.10O12.15 crystals in the glass, leaded to a reduction in the band gap of the glass. This resulted in an increased imprint of silver crystals within the glass layer, with more nano-silver crystals were deposited near the pyramid. Consequently, an optimal metallization contact was established between the silver grid and emitter. The average aspect ratio of silver grid improved from 0.415 for AG-1 to 0.469 for AG-3, which enhanced the photoelectric conversion efficiency of crystalline silicon solar cells.

Exploration of Griffiths phase, spin glass behaviour and memory effect in a frustrated Al2MnCoO7 pyrochlore compound

Al2MnCoO7 pyrochlore compound has been synthesized following the multistep solid-state ceramics route. The compound exhibits a monoclinic structure, which was confirmed through the X-ray diffraction pattern analysis. The magnetization measurements in both zero-field-cooled (ZFC) and field-cooled (FC) modes indicate that the compound undergoes a phase transition from paramagnetic (PM) to antiferromagnetic (AFM) state at the Néel transition temperature TN ∼31 K. Notably, below TN, there is a substantial discrepancy between the ZFC and FC curves, which can be ascribed to the existence of competing ferromagnetic (FM) and AFM interactions, resulting in a glassy behaviour. Additionally, the compound demonstrates a Griffiths phase above TN, signifying the presence of ferromagnetic clusters within the PM region of the material. The spin-glass behaviour is confirmed by the shift of maxima towards higher temperatures with increasing frequency in the ac susceptibility measurement. The memory effect also confirms the spin-glass nature of the compound. The Arrott's plots confirmed that the magnetic phase transition in the material to be a second-order type. Additionally, the material exhibited a maximum magnetic entropy change (−ΔS) value of 1.08 J/kg.K and a relative cooling power of 36.60 J/kg under an applied magnetic field of 5 T.

Sintering and crystallization kinetics of bioactive glass 13–93

This study investigates the sintering and crystallization behavior and kinetic of the bioactive glass (BG) 13–93 with nominal composition (in mol%): 54.6 SiO2 - 1.7 P2O3 - 22.1 CaO - 6.0 Na2O - 7.9 K2O - 7.7 MgO. Sintering and crystallization were investigated non-isothermally for various particle size fractions smaller than 315 µm as well as for bulk samples. Densification was not hindered by the presence of crystalline phases across all particle size fractions. Afterwards, wollastonite was found as the dominant crystal phase at higher temperature which resorb primary surface precipitation-like quartz crystallites. The growth direction shifts into volume when the sample surface is nearly covered. The crystal growth rate of wollastonite was calculated from the crystalline surface layer thickness measured during heating. The findings of this study are relevant for the high temperature processing of BG 13–93.

Structural investigation and thermal properties of Al2O3-PbO-B2O3 glasses

Two series of aluminum lead borate glasses, (Al2O3)y(PbO)35-y(B2O3)65 and (Al2O3)y(PbO)70-y(B2O3)30, were prepared and effect of PbO → Al2O3 substitution on their structure and thermal properties was studied. The semi-quantitative analysis of the Raman spectroscopy data was used to structural interpretation of glass transition behavior in the Al2O3-doped lead borate glasses. The mechanisms of structural reorganization of glassy network under PbO → Al2O3 substitution were found to differ for the studied series although Al3+ ions are incorporated in the glass network, mainly, in form of AlO4 units in the both cases. The formation of AlO4 tetrahedra is accompanied by transformation of various isolated borate anions into finite-sized metaborate chains as well as the conversion of four-fold coordinated [BØ3O−]− species with one non-bridging oxygen atom into fully polymerized [BØ4]− tetrahedra in the (Al2O3)y(PbO)70-y(B2O3)30 glasses. In the series of glasses with high concentration of B2O3, B[4] → B[3] transformation including the shift of [BØ4]− ↔ BØ2O− equilibrium toward the right side is the main process of structural reorganization caused by PbO → Al2O3 substitution. In this case, the change in the network connectivity is determined by competition between increasing the amount of Al-O-B bonds against the background of decreasing the amount of B-O-B bonds between borate structural species. In the B-poor series, the glass transition temperature increased with Al2O3 from 280 to 360 °C, and the crystallization peak onset occurs at 340 and 380 °C for the glasses with the 0 and 3 mol.% Al2O3 contents, respectively (higher aluminum oxide contents already prevent crystallization). In the B-rich series, Tg increases with the Al2O3 content from 430 to 490 °C, and the crystallization occurs at 560 °C only for the Al2O3-free glass. The structural relaxation behavior in the glass transition rage was described in terms of the Tool-Narayanaswamy-Moynihan model. The activation energy for the relaxation movements was found to be non-monotonous in case of both compositional series.

Magnetic and magnetocaloric effect of Er20Ho20Dy20Cu20Ni20 high-entropy metallic glass

Er20Ho20Dy20Cu20Ni20 high-entropy metallic glass exhibited excellent magnetic refrigeration material with a wide temperature range and high refrigeration capacity (RC) was reported. Er20Ho20Dy20Cu20Ni20 high-entropy metallic glass was observed with typical spin glass behavior around 15.5 K. In addition, we find that the magnetic entropy change (−ΔS M) originates from the sample undergoing a ferromagnetic (FM) to paramagnetic (PM) transition around 20 K. Under a field change from 0 T to 7 T, the value of maximum magnetic entropy change ( −ΔSMmax ) reaches 12.5 J/kg⋅K, and the corresponding value of RC reaches 487.7 J/kg in the temperature range from 6 K to 60 K. The large RC and wide temperature range make the Er20Ho20Dy20Cu20Ni20 high-entropy metallic glass be a promising material for application in magnetic refrigerators.

Structural behavior of copper monatomic metallic glass under various cooling conditions investigated by molecular dynamics simulations

The present research explores the structural characteristics of pure copper (Cu) metallic glass using the embedded atom method (EAM) potential in molecular dynamics simulations. Numerous techniques were used, such as coordination number analysis, Voronoi tessellation, and the radial distribution function (RDF). The findings demonstrate that at a cooling rate of 1012 K/s, crystallization begins. However, the separation of the second RDF peak indicates that under 0 GPa, copper metallic glass forms at cooling rates between 5 × 10¹² K/s and 1014 K/s, with the glass transition temperature (Tg) rising with faster cooling. Voronoi tessellation revealed a rise in icosahedral clusters with quicker cooling, while coordination number analysis indicated changes in the local structure and topology of copper metallic glass during the cooling process.

Enhancement of high-alumina glass and glass-ceramics through dual modification of Zn2+ and its mechanism

Dual modification with Zn2+ alters the crystalline behavior of high-alumina glass and enhances the resistance to crack propagation of high-alumina glass and glass-ceramics.

Impacts of substituting magnesium with zinc on crystallization behaviors in an aluminosilicate glass.

A series of zinc-magnesium mixed aluminosilicate glasses with the molar composition (1-r)MgO·rZnO·Al2O3·2.5SiO2, where r = 0.00, 0.25, 0.50, 0.65, 0.75, and 1.00, were fabricated to probe the effects of substitution of magnesium with zinc on crystallization behaviors. Based on the evolution of phase compositions as revealed by calorimetric behaviors and X-ray diffraction patterns, a series of transparent surface crystallized glasses ranging from high transparency for the pure Zn-end member to heavy translucency for the pure Mg-end member were fabricated through heat treatment at the first crystallization peak temperature for 20 min. With the substitution of Mg with Zn, the evolution of morphology unveiled by optical microscopy is ascribed to the alteration of crystal phases formed from the sole metastable Zn-β quartz solid solution to the coexistence of polycrystal phases containing Zn-β quartz solid solution, μ-cordierite, or α-cordierite. These findings are very helpful for optimizing the performance of crystallized aluminosilicate glasses.

The corrosion behavior of borosilicate glass in the presence of cementitious waste forms.

Borosilicate glasses are widely used for radioactive waste disposal due to their ability to incorporate a variety of contaminants and radionuclides while exhibiting high durability in various disposal scenarios. This research evaluated the dissolution of borosilicate glass using both single-pass-flow-through (ASTM C1662-18) and product consistency test (ASTM C1285-21) methods with different solutions, including a cementitious-contacted water (called grout-contacted, GC, from this point) and solutions with varying levels of dissolved cementitious species such as Si, Ca, Al. The results indicated that the presence of Ca plays a crucial role in suppressing glass corrosion, as evidenced by the slower normalized dissolution rates, which were one order of magnitude lower for boron and two orders of magnitude lower for rhenium, observed in both Ca-amended and GC solutions compared to the pH 12 buffer solution. This effect is attributed to the formation of a dense, low-porosity, and strongly bonded calcium silicate hydrate (CSH) layer on the glass surface, which implies that a glass corrosion process is influenced by ion exchange involving alkali ions Na+, K+, Ca2+, and hydrogen-containing species. A small number of glass particles treated in the GC solution showed minor corrosion pits in the form of shallow craters with an average diameter of approximately 500 μm. This observation is correlated with a significant reduction, 2000 to 3000 times lower, in the cumulative volume of glass pores, indicating that smaller pore voids were "sealed" in the presence of Ca2+ ions, likely attributed to the formation of CSH precipitation or other corrosion products such as calcium carbonate saturated from the grout solution. These findings suggest that the presence of dissolved Ca in the GC solution can slow down the dissolution of borosilicate glass, contrary to the expected trend of higher dissolution rates resulting from exposure to high alkaline and thus higher pH solutions.