Glass Formation Research Articles

Magnetic properties of soft magnetic composites prepared by gas-atomized glassy powders from a new Fe-based alloy with high glass-forming ability

Magnetic properties of soft magnetic composites prepared by gas-atomized glassy powders from a new Fe-based alloy with high glass-forming ability

Characterizing Rotational Dynamics and Heterogeneity via Single-Molecule Intensity Measurements.

Dynamic heterogeneity in glassy systems has typically been characterized at the single-molecule level by extracting rotational relaxation time scales from linear dichroism (LD) collected via two orthogonally polarized channels. However, in such measurements, localization precision is diminished due to photons lost relative to collection in a single detection channel. This poses challenges in characterizing rotational and translational dynamics simultaneously, as translational measurements require high localization precision. In this paper, we present a method for extracting rotational dynamics of glassy systems at the single-molecule level from intensity fluctuations of fluorescent probe molecules in a wide-field configuration without the use of a polarizing optical component. Through numerical analysis, we show that LD and intensity measurements probing rotational dynamics report similar, approximately second-order rotational correlation decays even at low signal to noise. Thus, within the assumptions of small, isotropic rotations, LD and intensity autocorrelation analysis should provide identical information on the time scale and heterogeneity of rotational dynamics. We then present experimental results that validate this numerical result, with direct comparison of LD and intensity-based approaches across probe molecules in both polymeric and small-molecule glass formers as well as across optical configurations. Our results demonstrate moderate correlation on a per-probe basis between rotational time scales obtained from both approaches, with deviations consistent with those expected in a dynamically heterogeneous system. We envision that this easily accessible strategy will be of use across disciplines for characterizing single-molecule rotational dynamics in limited signal situations and/or when high-precision localization is required.

Revealing hidden medium-range order in silicate glass formers using many-body correlation functions

Revealing hidden medium-range order in silicate glass formers using many-body correlation functions

Insights Into the Mechanochemical Glass Formation of Zeolitic Imidazolate Frameworks.

Metal-organic framework (MOF) glasses, known for their potential in gas separation, optics, and solid-state electrolytes, benefit from the processability of their (supercooled) liquid state. Traditionally, MOF glasses are produced by heating MOF crystals to their melting point and then cooling the liquid MOF to room temperature under an inert atmosphere. While effective, this melt-quenching technique requires high energy due to the high temperatures involved. It also limits the scope of new material development by restricting the compositional range to only those combinations of metal ions and linkers that are highly thermally stable. An alternative, mechanical milling at room temperature, has demonstrated its capability to transform MOF crystals into amorphous phases. However, the specific conditions under which these amorphous phases exhibit glass-like behavior remain uncharted. In this study, we explore the mechanochemical amorphization and vitrification of a variety of zeolitic imidazolate frameworks (ZIFs) with diverse linkers and different metal ions (Zn2+, Co2+ and Cu2+) at room temperature. Our findings demonstrate that ZIFs capable of melting can be successfully converted into glasses through ball-milling. Remarkably, some non-meltable ZIFs can also be vitrified using the ball-milling technique, as highlighted by the preparation of the first Cu2+-based ZIF glass.

Excellent magnetocaloric effect near the hydrogen liquefaction temperature of a binary Er67.5Co32.5 metallic glass

We reported the excellent magnetocaloric effect of a binary Er67.5Co32.5 metallic glass (MG) near the hydrogen liquefaction temperature. The binary MG ribbon was fabricated by a melt-spinning method. The Er67.5Co32.5 alloy exhibits a better glass formability than most of other rare earth (RE)-Co binary alloys. The maximum magnetic entropy change (−ΔSmpeak) and refrigeration capacity (RC) of the Er67.5Co32.5 amorphous ribbon under 0–5 T reach to 17.47 J/(kg × K) near its Curie temperature (Tc, ∼ 11 K) and 472 J/kg, both of which are rather high among the RE-based MGs with a Tc around 10 K and imply the potential application perspective as magnetic refrigerants for hydrogen liquefaction. The magnetization as well as magnetocaloric behaviors of the binary MG were observed, and the mechanism involved was investigated.

Mixed former effect in barium borophosphate glasses on the red (Eu3+)-blue (Eu2+) emission for LEDs

The synergistic mixing of P2O5 and B2O3 glass formers at a constant concentration of BaO as a glass modifier plays a vital role in generating a single-phase phosphor doped with Eu2O3 for white light-emitting diodes (WLEDs). Herein, a glass system of nominal composition xP2O5∙(50-x)B2O3∙49.5BaO∙0.5Eu2O3 (0 ≤ x ≤ 50 mol%) was prepared using a melt-quenching technique under normal atmospheric conditions. While the XRD patterns demonstrated the amorphous nature, the SEM micrographs proved the formation of cluster structures. Structural characterization using ATR-FTIR spectroscopy revealed the presence of main vibrational structural units associated with borate and phosphate glass formers, including BO3, BO4−, P=O, PO2−, and PO32−. The IR spectra at x = 0 and 50 mol% exhibit characteristic metaborate and metaphosphate absorption peaks, respectively. In contrast, the mixing of both B2O3 and P2O5 at equal concentrations (x = 25 mol%) has resulted in the absence of absorption peaks assigned to the BO3 and P=O units, thus indicating the mixed structural effect. This is assigned to the formation of B-O-P bonds, with the BO4−, PO2−, and PO32− as the main structural units. These structural changes affect the reduction process of Eu3+ to Eu2+, as demonstrated by the corresponding photoluminescence spectra and observed by the cathodoluminescence micrographs. Photoluminescence studies showed tunable emission from red (Eu3+) to white light (Eu2+ and Eu3+) under UV excitation, with the P2O5 content rising from 0 to 50 mol% due to the growing Eu2+ population formed by the reduction of Eu3+. The optical basicity was observed to decrease with the P2O5 content, favouring the reduction process. The demonstrated tunable single-host white phosphor makes this an attractive system for energy-efficient WLED applications.

Thermodynamic stabilities of NdFe3Al2, Nd5Fe17 and μ compounds and evolutions of microstructures and magnetic properties of Nd-Fe-Al alloys with nanocrystallites

In the Nd-Fe-Al ternary system, thermodynamic stabilities of three compounds, NdFe3Al2, Nd5Fe17 and μ, were determined by the equilibrated alloys, indicating that both NdFe3Al2 and μ ternary compounds are metastable phases, while Nd5Fe17 compound is a stable phase. Meantime, the microstructures of five representative as-cast alloy buttons are illustrated, which are consisted of crystalline phases and the complex of nanocrystallites + amorphous matrix (NCAM). The crystalline phases including Nd, Nd3Al, Nd2Fe17-xAlx and Nd6Fe13-xAl1+x as well as the nanocrystallites such as dhcp-Nd, fcc-Nd and Nd6Fe13-xAl1+x embedded in the amorphous matrix were observed. Particularly, it is concluded that the fcc-Nd nanocrystallites may be transformed from the fcc dense packing clusters of the amorphous matrix and/or dhcp-Nd nanocrystallites. The hard magnetic properties of these as-cast alloys can be attributed to NCAM and present a non-strict proportionate effect. The alloy composed of Nd + NCAM, with curie temperature (Tc) 515 K, displays the highest intrinsic coercivity Hci 305 kA/m and remanent magnetization Br 10.8 emu/g. Its good glass-forming ability is presented by the high ratio (Tx/Tm) 0.88 and the small interval (Tm-Tx) 105 K of the crystallization temperature (Tx) with the melting temperature (Tm). Since the present investigation focuses on phase stabilities, microstructural characterizations, magnetic properties and glass-forming ability of the Nd-Fe-Al alloys, the obtained results can provide a better understanding for advancing the design of the Nd-Fe-Al based hard magnets and amorphous materials.

Electron tailoring of thermal and magnetocaloric properties in Tb55TM17.5Al27.5 (TM = Fe, Co, and Ni) metallic glasses

Transition metal (TM) elements play a key role in determining properties of magnetocaloric materials. However, the effect of TM elements on the thermodynamic behavior and magnetocaloric effect (MCE) of metallic glasses (MGs) remains elusive. In this work, ternary Tb55TM17.5Al27.5 (TM = Fe, Co, and Ni) MGs without the complexities induced by high-entropy effects were designed. It is found that both the glass transition temperature (Tg) and the initial crystallization temperature (Tx) significantly increase with decreasing 3d electron number. It leads to the low values of Trg, γ, and γm for Tb55Fe17.5Al27.5, which is consistent with its poor glass forming ability (GFA) as evidenced by the obvious lattice fringes and structural order. Despite the mediocre value of magnetic entropy change (|ΔSMpk|) for Tb55Fe17.5Al27.5, its broader magnetic transition temperature of 110.4 K associated with ∼26% evident structural order yields the maximum relative cooling power (RCP) of 546.04 J kg−1 among three MGs. Moreover, a novel weighted method for evaluating 3d electron number by consideration of the concentration and species of TM elements was adopted to reveal an inverse correlation between the 3d electron number and Tg/Tx, as well as curie temperature (Tc), |ΔSMpk|, and RCP. It is found that with the decrease of the weighted 3d electron number of TM elements, the thermal stability of rare-earth-base MGs is effectively enhanced ascribed to the strong f - d orbital hybridization effect, along with the enhanced 3d - 3d exchange interaction that induces a high Tc. This work would help us more deeply understand the role of TM elements from the perspective of electronic structure, which is crucial for designing the novel MGs with a tunable MCE and GFA applied in various cryogenic refrigeration fields.

Design and characterization of biodegradable Mg−Zn−Ag metallic glasses

In order to develop the Mg−Zn−Ag metallic glasses (MGs) for biodegradable implant applications, the glass formation ability (GFA) and biocompatibility of Mg−Zn−Ag alloys were investigated using a combination of the calculation of phase diagrams (CALPHAD) and experimental measurements. High GFA potentiality of two alloy series, specifically Mg96−xZnxAg4 and Mg94−xZnxAg6 (x=17, 20, 23, 26, 29, 32, 35), was predicted theoretically and then substantiated through experimental testing. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques were used to evaluate the crystallinity, GFA, and crystallization characteristics of these alloys. The results showed that compositions between Mg73Zn23Ag4 and Mg64Zn32Ag4 for Mg96−xZnxAg4, Mg66Zn28Ag6 and Mg63Zn31Ag6 for Mg94−xZnxAg6 displayed a superior GFA. Notably, the GFA of the Mg96−xZnxAg4 series was better than that of the Mg94−xZnxAg6 series. Furthermore, the Mg70Zn26Ag4, Mg74Zn20Ag6, and Mg71Zn23Ag6 alloys showed acceptable corrosion rates, good cytocompatibility, and positive effects on cell proliferation. These characteristics make them suitable for applications in medical settings, potentially materials as biodegradable implants.

In situ boro-mullite phase formation in Glass–Ceramic glazes: Anatase–rutile phase transformations and microstructure properties

‘‘Boro-mullite’’ is the name for mullites produced through the synthesis of boron-rich material and playing a critical role in producing high-performance materials. Also, the stability of the anatase phase in the glaze and against temperature has been addressed and improved by many studies. In situ boro-mullite crystals generated using various glass-ceramic glaze compositions that contain TiO2 and their impact on the transformation of anatase into a rutile phase were examined in this study. Additionally, the samples' water absorption, bulk density, apparent porosity and shrinkage, Vickers hardness, and optical properties were evaluated at various Al2O3 and B2O3 amounts at 700 °C, 800 °C, 900 °C, 1000 °C and 1100 °C. X-ray diffraction analysis revealed that as the temperature and Al2O3 ratio rose, it triggered the boro-mullite phase formation. On the other hand, increasing the Al2O3 ratio led to a rise in the samples' sintering temperature and delayed the anatase to rutile phase transformation. Furthermore, the presence of corundum crystals retarded the anatase crystal size growth during the remodelling process of the conversion of anatase to rutile. While the increase in the B2O3 ratio sharpened the peaks of albite crystals, the formation of rutile crystals accelerated with the increase in temperature and caused inhibition of albite formation. The albite phase's presence facilitated the creation of the liquid phase and achieved the 0.010 % water absorption and 0 % apparent porosity values as well the highest bulk density and microhardness with 2.476 g/cm3 and 550 H V. The yellowness (+b∗) values were found to be the highest at 1100 °C where the rutile crystals reached their maximum size. The anatase-rutile conversion is postponed and the increase in the yellowness value is prevented by the glaze's formation of boro-mullite. FESEM-EDS analysis showed that the temperature was the driving force in the transformation of acicular boro-mullite crystal into highly acicular prismatic needle crystal and spherical anatase crystals into the rod shape rutile.

Optimizing Manufacturing of Zr–Cu–AI–NI Metallic Glasses via Laser Metal Deposition

Recently, it was discovered that the cutting-edge technique known as laser powder bed fusion (LPBF) is the best way to produce Zr-based bulk glasses made of metal (BMGs). While LPBF gives greater versatility, current state-of-the-art production techniques like copper mold casting and arc-melting have limits when it comes to implementing complicated designs. Furthermore, LPBF enables a delicate balance to be struck between producing intricate characteristics and sustaining suitable temperatures all through the whole operation. Because of its exceptional features and practical availability, this research focuses on optimizing the process variables for a specific Zr-based alloy, AMZ4, which is produced by additive manufacturing in order to optimize both its mechanical and thermal characteristics. Belonging to the class of zirconium-based alloys known as bulk metallic glasses (BMG), Zr57Cu15Ni10AI5 (or Vit-106) has an excellent glass-forming ability and shows great promise. By casting, a BMG alloy may be transformed into workpieces that are about one centimeter in size in all three dimensions. Nevertheless, crystallization is induced when the cast size is further increased since it reduces the cooling rate. By building a workpiece from many melt sections with the cooling rate maintained above the critical one, selective laser melt (SLM) is an established technique for overcoming size restrictions for BMGs. Partially crystallized BMG is now an issue with SLM-obtained components. The effect of SLM process variables on partial crystallization is investigated in this paper. You may regulate the size and intensity of the inclusion by altering the speed of the laser scanning. Microhardness and wear resistance may be improved by incorporating submicron crystalline inclusions into the amorphous matrix by SLM.

Rapid vitrification of Sr-loaded zeolite by microwave sintering for disposal of secondary radioactive wastes: Mechanism and performance

The rapid solidification of Sr-loaded zeolite, a potential secondary solid waste, is highly urgent for nuclear post-accident remediation. Microwave heating is first employed to dispose of spent Sr-loaded adsorbent. The adsorption kinetics and isotherm model of zeolite NaX for Sr(Ⅱ) was reported. Meanwhile, the effect of B2O3 additive on the phase evolution, microstructure, and chemical durability was systemically investigated. The results showed that the B2O3 addition could effectively lower the sintering temperature from 1200 ℃ to 1000 ℃ via microwave heating. The stable glass form was successfully obtained with sintering temperature of 1000 ℃, B2O3-doped amount of 25 wt.%, and dwell time of 40 min. The Sr was homogeneously distributed in the sintered matrix without substantial enrichment. Moreover, the leaching rate of Sr in the solidified form was about 1.19 × 10-5 g·m−2·d−1 after 42 days, demonstrating its excellent chemical stability. This study indicated rapid low-temperature vitrification of Sr-loaded zeolite by microwave heating was a promising approach for removal and immobilization of Sr in radioactive wastewater.

Novel phosphate bioglasses and bioglass-ceramics for bone regeneration

Bioactive glasses and glass-ceramics are biomaterials characterized by excellent bone bonding abilities. Many different bioactive glass formulations have been studied since the introduction of 45S5 bioglass by Larry Hench. Among silicate and borate bioglasses the phosphate-based ones seem to be interesting in drug delivery systems applications due to their high solubility and low toxicity. In this study novel phosphate bioactive glasses from the composition of P2O5 – CaO – Ca(OH)2 – KF – Na2O – TiO2 and P2O5 – CaO – Ca(OH)2 – ZnO – KF –TiO2 modified with 500 ppm or 2000 ppm of HAuCl4 – 3H2O were obtained by traditional melt-quenching technique. Glass crystallization temperature was measured by DSC calorimetry. The bioglasses were partially crystallized above the crystallization temperature and the bioactive glass-ceramic based on the composition of the parent glasses was obtained. The FT-IR structural studies were performed to detect the presence of structural units beneficial for bioactivity of the materials. Crystalline phases of the bioglass-ceramics were identified with XRD. All bioglass-ceramics contained bioactive β-pyrophosphate. The obtained bioglasses and glass-ceramics were incubated in SBF to evaluate their bioactivity. Only P2O5 – CaO – Ca(OH)2 – KF– Na2O–TiO2 bioglass-ceramics developed apatite-like layer on the surface after incubation in Simulated Body Fluid and was chosen as the material for future studies. The impact of the chemical composition of the bioglass, presence of particular structural units and bioglass-ceramic phase composition on the in vitro bioactivity was discussed.

High-entropy non-covalent cyclic peptide glass.

Biomolecule-based non-covalent glasses are biocompatible and biodegradable, and offer a sustainable alternative to conventional glass. Cyclic peptides (CPs) can serve as promising glass formers owing to their structural rigidity and resistance to enzymatic degradation. However, their potent crystallization tendency hinders their potential in glass construction. Here we engineered a series of CP glasses with tunable glass transition behaviours by modulating the conformational complexity of CP clusters. By incorporating multicomponent CPs, the formation of high-entropy CP glass is facilitated, which-in turn-inhibits the crystallization of individual CPs. The high-entropy CP glass demonstrates enhanced mechanical properties and enzyme tolerance compared with individual CP glass and a unique biorecycling capability that is unattainable by traditional glasses. These findings provide a promising paradigm for the design and development of stable non-covalent glasses based on naturally derived biomolecules, and advance their application in pharmaceutical formulations and smart functional materials.

Transparent and high-porosity aluminum alkoxide network-forming glasses

Metal-organic network-forming glasses are an emerging type of material capable of combining the modular design and high porosity of metal-organic frameworks and the high processability and optical transparency of glasses. However, a generalizable strategy for achieving both high porosity and high glass-forming ability in modularly designed metal-organic networks has yet to be developed. Herein, we develop a series of aluminum alkoxide glasses and monoliths by linking aluminum-oxo clusters with alcohol linkers. A bulky monodentate alcohol modulator is introduced during synthesis and act as both network plasticizer and pore template, which can be removed by the subsequent solvent exchange to give gas accessible pores. Glasses synthesized with the modulator template exhibit well-defined glass transitions in their as-synthesized form and high surface areas up to 500 m2/g after activation, making them among the most porous glassy materials. The aluminum alkoxide glasses also have optical transparency and fluorescent properties, and their structures are elucidated by pair-distribution functions, spectroscopic and compositional analysis. These findings could significantly expand the library of microporous metal-organic network-forming glasses and enable their future applications.

Additive manufacturing of quartz glass using coaxial wire feeding technology

This study explores the process of coaxial wire feeding and melting for quartz additive manufacturing using Direct Energy Deposition (DED). Quartz glass, valued for its excellent mechanical, optical, and thermal properties, is widely used in semiconductor, aerospace, and optical communication industries. Additive manufacturing offers advantages such as cost-effective materials, rapid formation, and customization of structures. However, current methods for additive manufacturing of quartz glass often result in low quality or require complex post-processing, particularly for optical components. In optics, there is a demand for high-quality, straightforward processes, and custom-shaped quartz glass. This article presents a coaxial wire feeding mechanism wherein quartz wire is fed vertically downward along the optical axis into the melting zone created by a CO2 laser, facilitating smooth material deposition onto the molten zone’s surface. Laser power, wire feeding speed, substrate movement speed, and defocusing distance are key factors influencing the quality of single-layer quartz glass formation. Positive defocusing was found to have a beneficial impact on single-layer quartz glass additive manufacturing. Subsequently, optimized process parameters enabled the production of uniformly cross-sectional single-layer quartz glass. Microscopic morphology analysis and temperature field simulation were conducted on the experimental results before and after optimization. Finally, complex quartz glass structures were additively manufactured using the optimized experimental parameters. Results demonstrate that coaxial wire feeding technology has significant potential for achieving uniform dimensions and complex structures in quartz glass additive manufacturing.

Thermal and Thermomechanical Analysis of Amorphous Metals: A Compact Review

Metallic glasses are amorphous metals that are supercooled to a frozen, glassy state and lack long-range order, in contrast to conventional metal structures. The lack of a well-ordered structure largely contributes to the unique properties exhibited by these materials. However, their synthesis and processability are defined and thereby constrained by a plethora of thermal and mechanical parameters. Therefore, their broader utilization in the scientific field and particularly in the related industry is somewhat hindered by the limitations related to preparing them in higher amounts. This may be overcome by changing the approach of metal glass formation to a bottom-up approach by utilizing solid-state plasma techniques, such as spark plasma ablation. Another important aspect of amorphous metals, inherently related to their non-equilibrium metastable nature, is the necessity to understand their thermal transformations, which requires unconventional thermal analysis methods. Therefore, this minute review aims to highlight the most important conceptual parameters behind configuring and performing conventional and advanced thermal analysis techniques. The importance of calorimetry methods (differential and fast scanning calorimetry) for the determination of key thermal properties (critical cooling rate, glass-forming ability, heat capacity, relaxation, and rejuvenation) is underscored. Moreover, the contributions of thermomechanical analysis and in situ temperature-dependent structural analysis are also mentioned. Namely, all of the mentioned temperature-dependent mechanical and structural analyses may give rise to the discovery of new glass systems with low critical cooling rates.

Compositional dependence of glass-forming ability, mechanical and magnetic properties of Ce-Ni-Al (Ga) alloys

The glass-forming ability, mechanical and magnetic properties of Ce60Ni25Al15-xGax (x=0, 4, 8 and 15) melt-spun alloys have been investigated. All the alloys show the formation of glassy phase. The supercooled liquid region increases with increase in Ga addition and becomes maximum for x=15 indicating its better glass-forming ability for this composition. A new metallic glass (MG) composition Ce60Ni25Ga15 has been found upon complete substitution of Al by Ga. The mechanical behavior of these alloys has been studied by determining various indentation parameters such as micro-hardness, yield strength and Meyer’s exponent. The microhardness property of the Ce-Ni-Al alloy is improved by the addition of Ga. The difference in the formation of shear bands for x=0 and 15 alloys are discussed by estimating the pile-up parameter. The magnetization (M-H) curves of all the samples at 5 K show paramagnetic characteristics with no magnetic hysteresis. The findings reveal that the concentration of Ga has a significant impact on the properties of these alloys.

HoDyGdCoAl high-entropy amorphous alloys working at full temperature range for hydrogen liquefaction with large magnetocaloric effects

Cryogenic magnetic refrigeration materials based on magnetocaloric effect can be used for hydrogen liquefaction. In this work, glass formation ability (GFA), magnetocaloric effect (MCE), refrigeration performance of melt-extracted HoDyGdCoAl amorphous ribbons have been investigated. Amorphous ribbons undergo a second order magnetic phase transition which achieve a table-like behavior broaden the range of magnetic transition temperature in hydrogen liquefaction.The maximum magnetic entropy change (-ΔSmaxM), the δTFWHM and the refrigeration capacity (RC) achieved 10.9 J/ (kg K), 84.2 K and 742.4 J/ kg (x = 5) and 11.2 J/ (kg K), 69.8 K and 643.0 J/ kg (x = 20) under a magnetic field change of 7 T, respectively. Combining wide magnetic transition temperature and large refrigerant capacity, the present amorphous ribbons can be used as potential magnetic refrigerant materials in hydrogen liquefaction temperature region.

Extremely large Cl isotopic fractionation in Chang'e-5 impact glass beads

Lunar materials have recorded a very large δ37Cl variation, and the mechanism causing this variation has yet to be determined. We measured the F and Cl contents and the δ37Cl in Chang'e-5 impact glass beads using a nanoscale secondary ion mass spectrometry. These glass beads exhibit the largest δ37Cl variation observed to date, ranging from –0.7 ‰ to 119 ‰. Furthermore, the δ37Cl values are roughly negatively correlated with the Cl concentration. The correlations between F and Cl concentrations differ for homogeneous and heterogeneous glass beads. Our calculations indicate that NaCl (g) and HCl (g) degassing may have been the pivotal mechanism that elevated the δ37Cl value, with >50 % of Cl in the melt evaporating during glass formation. The glass beads may have incorporated the chlorine species condensed from early evaporation. Our results provide direct evidence to constrain the impact-induced degassing process of Cl on airless celestial bodies.