As-quenched Glass Research Articles

Effect of Cobalt on the Microstructure of Fe-B-Sn Amorphous Metallic Alloys

Fe78B15Sn7 and (Fe3Co1)78B15Sn7 amorphous metallic alloys were prepared using the method of planar flow casting. The amorphous nature of ribbons containing 7 at. % Sn was verified by X-ray diffraction. The resulting chemical composition was checked by flame atomic absorption spectroscopy and by mass spectrometry with inductively coupled plasma. The microstructure of the as-quenched metallic glasses was investigated by 57-Fe and 119-Sn Mössbauer spectrometry. The experiments were performed with transmission geometry at 300 K, 100 K, and 4.2 K, and in an external magnetic field of 6 T. The replacement of a quarter of the Fe by Co did not cause significant modifications of the hyperfine interactions in the 57-Fe nuclei. The observed minor variations in the local magnetic microstructure were attributed to alterations in the topological short-range order. However, the in-field 57-Fe Mössbauer spectra indicated a misalignment of the partial magnetic moments. On the other hand, the presence of Co considerably affected the local magnetic microstructure of the 119-Sn nuclei. This was probably due to the higher magnetic moment of Co, which induces transfer fields and polarization effects on the diamagnetic Sn atoms.

Switching, optical, Raman, and Morphological investigations on Sn doped SiTe glasses and thin films

In this work, the electrical switching, optical and structural properties of Sn doped Si-Te glasses and thin films are studied. The Si20Te80-xSnx (1 ≤ x ≤ 5) glasses and thin-film samples are prepared using melt quenching and flash evaporation techniques respectively. All prepared bulk and thin-film samples exhibited smooth memory type of switching behaviour. Thicknesses of the thin film samples are found to be in the range of 92-111 nm. The electrical switching fields and energy bandgap of Si20Te80-xSnx (1 ≤ x ≤ 5) thin films have decreased as the concentration of Sn dopant is increased. Micro-Raman investigation on as-quenched Si20Te80-xSnx glasses is performed to study the structural network and its progression with composition. The reported Raman peaks are attributed to crystalline Te and the vibrational modes of Sn lattice. Scanning Electron Microscopy studies on switched and unswitched regions of Si20Te80-xSnx (1 ≤ x ≤ 5) glasses reveal the formation of a crystalline channel that acts as a conduction path between the two electrodes in the switched region.

Predicting the location of shear band initiation in a metallic glass

We report atomistic simulation results which indicate that the location of shear banding in a metallic glass (MG) can be ascertained with reasonably high accuracy solely from the undeformed static structure. Correlation is observed between the location of the initiation of shear bands in a simulated MG and the initial distribution of the density of fertile sites (DFS) for stress-driven shear transformations identified a priori based on a deep learning model devised in our recent work [Fan and Ma, Nat. Commun. 12, 1506 (2021)]. In addition, we demonstrated that one can judge whether a glass is brittle or ductile solely based upon its initial DFS distribution. These validate that shear bands in MG arise from non-linear instabilities, and that the as-quenched glass structure contains inhomogeneities that influence these instabilities. This work also reveals an important subtlety regarding the non-deterministic nature of athermal quasistatic shear simulations.

Iron enriched peraluminous glasses: Incorporation limit and effect of iron on glass transition temperature and viscosity

This study investigates the effect of iron oxide Fe2O3 on the homogeneity, viscosity, and glass transition temperature (Tg) of peraluminous glasses. As-quenched glass samples elaborated at 1350 °C show an incorporation limit around 17.5 wt% of Fe2O3 (10.4 mol%), while slowly cooled glass samples show a limit of 7.5 wt% of Fe2O3 (4.2 mol%). Iron in the peraluminous glasses investigated was detected under three configurations: 6-fold coordinated 6Fe3+ in majority, 4-fold coordinated 4Fe3+ and 6-fold coordinated 6Fe2+. It was observed that Fe2O3 addition has a strong fluidifying effect on peraluminous glasses and tends to slightly decrease the glass transition temperature Tg, depending on its thermal history.

Switching, Raman and morphological studies on Si20Te74Sn6 chalcogenide glass

Chalcogenide materials are getting lot of research attention due to their ability to switchfrom an amorphous to a crystalline phase with lower threshold voltage which is a primary requirement for fabricating phase-change memory. Here we have prepared the Si20Te74Sn6 bulk sample using melt quenching technique. It has been observed that the sample exhibits a memory switching phenomenon with the addition of Sn dopant on Si-Te base glasses. Memory switching is mainly observed due to Te rich host matrix and the metallicity of Sn dopant. The sample exhibits a linear variation of threshold voltage with an increase in thickness, which is compatible with memory switching behaviour. Raman studies on as-quenched Si20Te74Sn6 glass are carried out to study the structural behaviour of the network. The observed Raman peaks are attributed to crystalline tellurium and the vibrational modes of Sn/Si lattice. Morphological studies on switched and un-switched samples using SEM reveal a structural alteration in the switched region, which can also be related to the creation of conducting channel between two electrodes during memory switching.

Structure, mechanical properties and nanocrystallization of (FeCoCrNi)-(B,Si) high-entropy metallic glasses

New high-entropy metallic glasses were produced by adding B and Si to the Fe25Co25Cr25Ni25 high entropy alloy. Extremely hard materials were obtained by inducing structural relaxation and nanocrystallization in the original amorphous metals. In this work we study the effects of the composition and annealing treatments on the structure and the mechanical properties. The changes in structure during heating treatments were determined by in situ synchrotron X-ray diffraction and the mechanical behavior was studied by nanoindentation. The mechanical properties of the as-quenched glasses were tuned through the annealing treatments, obtaining amorphous/nanocrystalline composites appropriate for highly demanding, wear resistance applications. The relative amount of B and Si is shown to determine the main nanocrystalline phase, FCC or BCC, which has a key influence on the mechanical properties.

Luminescence properties of CaMoO4 nanoparticles embedded borate composite glass

Transparent glasses of the 1.2CaO–0.2MoO3–B2O3 system were fabricated using the conventional melt-quenching technique. The glasses were heat-treated above the glass transition temperature (Tg) to yielded nanocrystalline composites of CaMoO4 (CMO) and CaB2O4 (CBO). The structural characterization of as-quenched and heat-treated glasses corroborated the crystallites of CaMoO4 and CaB2O4 using powder X-ray diffraction (XRD) and Raman spectroscopy. The various morphologies of the samples were studied using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Optical transmittance spectrum for as-quenched glass shows, approximately, 77% transparency (uncorrected for the reflection losses) from 2600 ​nm to 325 ​nm with a lower cut-off wavelength at 324 ​nm. The optical band gap (Eg) and refractive index (η) of the as-quenched transparent glass were found to be 3.43 ​eV and 1.615, respectively. Room-temperature photoluminescence properties of the as-quenched and glass nanocrystal composites (GNC) exhibit broad blue emission with UV excitation wavelengths (using laser and Xe lamp). Such distribution of CMO crystallites of nano-dimensions embedded in borate glass matrix could be used for various PL applications.

Insights into the physical aging in chalcogenide glasses: A case study of a first-generation As2Se3 binary glass

• The experimental/theoretical understanding of physical aging in chalcogenide glasses has been reviewed. • General symptoms, peculiarities, and characteristics of PhA have been discussed. • Investigations of PhA in industrial glass (As 2 Se 3 ) have been reported. The time-dependent variation in the physical properties is one of the most interesting and mysterious behaviors of melt-quenched disordered solids (like polymer glasses, metallic glasses, and especially in chalcogenide glasses). This phenomenon is recognized as physical aging which reveals that the as-quenched glass stays in a meta-stable state (i.e., a thermodynamically non-equilibrium state) and so a thermally activated structural relaxation is the general characteristics of each glass as a consequence of natural or artificial physical aging (PhA). This review starts with the general introduction of PhA and its features. Different perceptive and peculiarities of PhA have been discussed keeping in mind the case of long-term PhA and anti-aging effects of arsenic in the chalcogenide glasses (ChGs) of the Se-As system. Further, we have reported the case study of As 2 Se 3 stoichiometric glass and the results of some new observations during the natural aging of the Arsenic Tri-Selenide glass (g-As 2 Se 3 ). The thorough inspection of PhA effects in this industrial glass is done after storing at ambient temperature in a glovebox for ten years. Thermal analysis is done by using differential scanning calorimetry. The XRD and TEM/SEM techniques have been employed for structural analysis. The information of various kinds of bonding is acquired by using Raman spectroscopy. Also, we have determined the thermal stability parameter, Vickers hardness, compactness, fragility, and density of the fresh and old samples of As 2 Se 3 glass to see the consequences of PhA. Finally, the new advances and present status related to the studies of PhA have been discussed.

Surface crystallization of BiOCl on 2Bi2O3–B2O3 glasses for photocatalytic applications

The present manuscript deals with crystallization of BiOCl structure over the 2Bi2O3–B2O3(BBO) glass surface and its photocatalytic response. The crystallization of BiOCl is obtained through systematic etching of the surface of BBO glass from the solution of hydrochloric acid of three different concentrations, and these samples are depicted with name BBO HCl1, BBO HCl2, and BBO HCl3, respectively. XRD results confirm the formation of BiOCl phase. Scanning electron microscopy reveals the flower-like hierarchical structure assembled with numerous petals over BBO HCl1, BBO HCl2, and BBO HCl3 glass samples. The contact angle of water drop is measured 90° for the as-quenched BBO, and 35°, 22°, and 16° for the BBO HCl1, BBO HCl2, and BBO HCl3 glass samples, respectively. The decrease in contact angle shows increase in the hydrophilicity of the samples. In comparison to BBO glass sample the photocatalytic activities of BBO HC1, BBO HCl2, and BBO HCl3 glass samples are investigated under the exposure of UV light. Photocatalytic degradation rate of methylene blue (MB) is observed the highest for BBO HCL3 and decreases for BBO HC1, BBO HCl2, and as-quenched BBO glass, relatively. Low-cost etching method for BiOCl crystal growth over the BBO glass substrate for superior photocatalytic property suggests the suitability of these samples as well as method in the degradation of pollutants and in the production for numerous commercial applications.

Mechanical Properties of Silver Nanoparticles Induced Europium Doped Phosphate Glasses for Red Laser Application

Magnesium-zinc-sulfophosphate glasses with varying concentration of Silver nanoparticles (AgNPs) composition of 63.5P2O5–20MgO–15ZnSO4–1.5Eu2O3–zAgNps (z = 0.0, 0.1, 0.3, 0.5, 0.7,0.9 and 1.1 g in excess) was prepared using melt-quenching technique. The as-Quenched glass samples were characterised to ascertain the correlation between physical and mechanical characteristics. The enhanced Young’s, shear, and bulk modulus of glasses noted a comparative rise in AgNPs contents. The Poisson’s ratio improved from (0.0978 to 0.1416) while Vickers hardness (from 0.0658 to 0. 0.0682 GPa) as well as GC12 (from 0.8350 to 0.8916) were enhanced. Photoluminescence spectra (emission) of the glasses showed four peaks at 593, 613, 654, and 701 nm equivalent to 5D0→7F0, 5D0→7F2, 5D0→7F3, and 5D0→7F4 transitions in europium in which the intense peak was observed at 613 nm (red). High Quantum Efficiency (η = 97.9%) was achieved due to significant PL enhancement. The studied glass may be useful for the development of red laser

Physical, structural and optical characterization of Dy3+ doped ZnF2-WO2-B2O3-TeO2 glasses for opto-communication applications

Abstract A series of ZnF2-WO2-B2O3-TeO2 (ZWFBT) glasses doped with different concentration of Dy3+ ions were prepared by using the melt quench method. The non-crystalline behavior of as-quenched ZWFBTDy glasses was approved by XRD spectra. The presence of different functional groups were identified by monitoring FT-IR spectra of ZWFBTDy glasses. The Differential Scanning Calorimetry (DSC) was used to estimate glass transition temperature (Tg) and thermal stability (ΔT) of an un-doped glass along with doped glasses. Physical parameters were estimated for Dy3+ doped ZWFBT glasses by using the formula available in the literature. The energy band gaps of as-quenched ZWFBTDy glasses were estimated by using three different theoretical models such as Mott and Davis relation, Hydrogenic Excitonic Model (HEM), and Urbach analysis. The optical absorption spectra were used to estimate the bonding parameters (δ) for elucidating the kind of bonding amide Dy3+ ions and its nearby ligands in the as-quenched glasses. The obtained experimental data from optical absorption spectra were compared with theoretical data calculated in the ambit of the Judd-Ofelt (J-O) theory. The J-O intensity parameters were estimated and a similar trend was observed ( Ω 2 > Ω 6 > Ω 4 ) for the as-prepared ZWFBTDy glasses. The results obtained using J-O intensity parameters are found consistent with the bonding parameters. The radiative parameters such as branching ratio, radiative transition, radiative lifetime, total radiative transition, absorption, and emission cross-sections were evaluated and discussed. The gain coefficient was evaluated for the NIR transitions of as-quenched ZWFBTDy glasses. The obtained results suggested that the as-prepared ZWFBTDy glasses were auspicious candidates for laser emission and optical communication applications.

Crystallization mechanism of Bi2Ti2O7 from 0.25Bi2O3-TiO2-0.25Na2O-SiO2 glass

We have studied the crystallization kinetics of pyrochlore Bi2Ti2O7 (BTO) from 0.25Bi2O3-TiO2-0.25Na2O-SiO2 (BTNSO) glass under isothermal and non-isothermal conditions. On the course of crystallization, only BTO crystal within the confined size under 100 nm is formed and the rest of the components of as-quenched BTNSO glass remains as a remanent glass even at the final stage of crystallization. The crystallization mechanism of BTO belongs to a constant nucleation rate with the diffusion-controlled growth and any heterogeneous nucleation or impingement in growth is not pronounced. The change of phonon modes in the senses of energy and population for different phases enables us to get the insight of crystallization in the view of both macroscopic and microscopic points.

Judd-Ofelt itemization and influence of energy transfer on Sm3+ ions activated B2O3–ZnF2–SrO–SiO2 glasses for orange-red emitting devices

Augmenting the photoluminescence (PL) properties of Samarium (Sm3+) doped Zinc Strontium fluoro-borosilicate glass (ZSFBSi glass) by varying the Sm3+ ions concentration unlocks new prospects for their application as luminescent devices. This paper presents absorption, photoluminescence (PL), energy transfer and color chromaticity parameterization of ZSFBSi glass doped with Sm3+ ions concentrations. The Judd-Ofelt (J-O) theory in correlation with absorption as well as PL spectra leads to the estimation of radiative parameters of the excited luminescent states of Sm3+ ions needed to understand the luminescent potentiality of the as-prepared glasses. The absorption spectral data reveals the nature of bonding between Sm3+ ions and oxygen ligands in the as-quenched glasses as ionic and the result is consistent with the J-O analysis. The PL spectra of as-quenched glasses exhibit greenish-yellow, orange-red, light red and red color ascribed to 4G5/2 → 6H5/2, 6H7/2, 6H9/2, 6H11/2 emission bands at 563, 599, 646 and 706 nm, respectively. The PL intensity enhances with an escalation in Sm3+ ions content until 1.0 mol% and reduces thereafter, owing to a proficient energy transfer (ET) process. The Dexter theory and Inokuti-Hirayama (I–H) model identified the foremost ET process associated with the as-quenched glasses as dipole-dipole in nature. The CIE color coordinates (x, y) and Correlated Color Temperature (CCT) were calculated to cognize the effectiveness of as-quenched glasses in radiative cool white emission. The estimated branching ratios, emission cross-sections, gain bandwidth, quantum efficiency, optical gain, color coordinates and CCT finally reveals that the as-quenched glasses can be used in luminescent devices and amide all, 1.0 mol% Sm2O3 in ZSFBSi glass is highly appropriate for white LEDs as well as orange-red luminescent devices.

Structure of NaFeSiO4, NaFeSi2O6, and NaFeSi3O8 glasses and glass-ceramics

AbstractThe crystallization of iron-containing sodium silicate phases holds particular importance, both in the management of high-level nuclear wastes and in geosciences. Here, we study three as-quenched glasses and their heat-treated chemical analogs, NaFeSiO4, NaFeSi2O6, and NaFeSi3O8 (with nominal stoichiometries from feldspathoid, pyroxene, and feldspar mineral groups, i.e., Si/Fe = 1, 2, and 3, respectively) using various techniques. Phase analyses revealed that as-quenched NaFeSiO4 could not accommodate all Fe in the glass phase (some Fe crystallizes as Fe3O4), whereas as-quenched NaFeSi2O6 and NaFeSi3O8 form amorphous glasses. NaFeSi2O6 glass is the only composition that crystallizes into its respective isochemical crystalline polymorph, i.e., aegirine, upon isothermal heat-treatment. As revealed by Mössbauer spectroscopy, iron is predominantly present as fourfold-coordinated Fe3+ in all glasses, though it is present as sixfold-coordinated Fe3+ in the aegirine crystals (NaFeSi2O6), as expected from crystallography. Thus, Na-Fe silicate can form a crystalline phase in which it is octahedrally coordinated, even though it is mostly tetrahedrally coordinated in the parent glasses. Thermal behavior, magnetic properties, iron redox state (including Fe K-edge X-ray absorption), and vibrational properties (Raman spectra) of the above compositions are discussed.

Correlation of Optical and Mechanical Properties of Silver Nanoparticles Sensitized Europium Doped Phosphate Glasses

Magnesium-zinc-sulfophosphate glasses with various concentration of Silver nanoparticles (AgNPs) compose of 63.5P2O5–20MgO –15ZnSO4–1.5Eu2O3 –yAgNps (y = 0.0, 0.1, 0.3, 0.5, 0.7,0.9 and 1.1 g in excess) were prepared via melt-quenching method. As-Quenched glasses were then characterized to establish the relationship between optical and mechanical characteristics. Densities were found to increase from 3.0720 to 4.3304 g.cm-3 with increase in AgNPs embedding levels, suggesting the network shrinkages and enhanced compactness. The Young’s, shear and bulk modulus of glasses were observed to enhance with the increase in AgNPs contents. The Poisson’s ratio value increased from (0.0978 to 0.1416) while values of both Vickers hardness (from 0.0658 to 0. 0.0682 GPa) as well as (from 0.8350 to 0.8916) were increased. This necessitate the evaluation of ultrasonic properties and mechanical properties of the synthesized glasses and further analysed by various analytical tools. The studied glass may be useful for the development of hard surface engineering.

Judd-Ofelt Parameterization and Luminescence Characterization of Dy3+ Doped Oxyfluoride Lithium Zinc Borosilicate Glasses for Lasers and w-LEDs

ABSTRACT In this work, Oxyfluoride Lithium Zinc Borosilicate glasses of varying Dy3+ ions concentration were prepared by using a melt quench technique. The optical and luminescence characteristics of Dy3+ ions were analyzed by XRD, absorption and emission spectroscopy. The Judd-Ofelt (J-O) parameters estimated by correlating absorption spectral measurements. The emission profiles displayed three principle bands in blue, yellow, red regions and quenching was detected at 1 mol% of Dy3+ ions. The radiative properties were evaluated for the protuberant luminous levels of Dy3+ ions within the ambit of J-O theory. The color coordinates at 351 nm pumping wavelength provide the worthy white emission. The decay profiles of 4F9/2→6H13/2 showed exponential nature up to 1 mol% and non-exponential elsewhere. It has been observed that 1.0 mol % Dy3+ ions doped OFLZBS glasses are aptly fit for white light generation. This observation showed that as-quenched glasses may have great potentials for lasers and w-LEDs applications.

Structural relaxation affecting shear-transformation avalanches in metallic glasses.

Avalanche behaviors, characterized by power-law statistics and structural relaxation that induces shear localization in amorphous plasticity, play an essential role in deciding the mechanical properties of amorphous metallic solids (i.e., metallic glasses). However, their interdependence is still not fully understood. To investigate the influence of structural relaxation on elementary avalanche behavior, we perform molecular-dynamics simulations for the shear deformation test of metallic glasses using two typical metallic-glass models comprising a less-relaxed (as-quenched) glass and a well-relaxed (well-aged) glass exhibiting a relatively homogeneous deformation and a shear-band-like heterogeneous deformation, respectively. The data on elementary avalanches obtained from both glass models follow the same power-law statistics with different maximum event sizes, and the well-relaxed glass shows shear localization. Evaluating the spatial correlation functions of the nonaffine squared displacements of atoms during each elementary avalanche event, we observe that the shapes of the elementary avalanche regions in the well-relaxed glasses tend to be anisotropic, whereas those in the less-relaxed glasses are relatively isotropic. Furthermore, we demonstrate that a temporal clustering in the direction of the avalanche propagation emerges, and a considerable correlation between the anisotropy and avalanche size exists in the well-relaxed glass model.

Effects of heat treatment on the structural and electrical conductivity of Fe2O3–P2O5–PbO glasses

Glasses having compositions xFe2O3–(80 − x)P2O5–20PbO with x = 20, 25, 30, 35 mol% were prepared by traditional glass melt-quenching method. The effects of the heat treatment of glasses on their structural and electrical conductivity were studied by X-ray diffraction (XRD), differential scanning calorimeter, density (ρ) and dc conductivity (σ). The glass transition temperature (Tg) was observed to increase with Fe2O3 content. The density of the prepared glass and corresponding glass–ceramics increases with Fe2O3 content. XRD of as-quenched glass samples confirm the amorphous nature. Triclinic lead iron phosphate PbFe2(P2O7)2 is the main crystalline ceramic phase formed after heat treatment at 973 K, of 20 and 25 Fe2O3 mol% with average crystallite size of 74 nm. Hexagonal iron phosphate FePO4 phases appeared with Fe2O3 exceeded 30 mol%. The high-temperature conductivity is well explained by polaronic hopping conduction model. It is observed that in this system non-adiabatic hopping conduction is present. The longitudinal optical phonon frequency (νο) and density of state N(EF) of the prepared glass and corresponding glass–ceramics are reasonable for the localized states.

Micron-sized spinel crystals in high level waste glass compositions: Determination of crystal size and crystal fraction

The compositions utilized for immobilization of high-level nuclear wastes (HLW) are controlled using glass property models to avoid the deleterious effects of crystallization in the high-level waste (HLW) vitrification melters. The type and size of the crystals that precipitate during melter operations (typically at 1150 °C) and idling (∼1000 °C) are significantly impacted by glass composition and thermal history. This study was conducted to measure the impact of melt composition and heat treatment temperature on crystal size and fraction. A matrix of 31 multi-component glasses canvasing the expected Hanford HLW compositional space was developed and the glasses fabricated and heat treated at 850, 900, and 950 °C. The crystal amounts, as determined by X-ray diffraction, varied from 0.2 to 41.0 wt%. Spinel concentrations ranged from 0.0 to 13.8 wt%. One glass of the matrix did not precipitate spinel and contained 0.2 wt% RuO2, which was assumed to be undissolved from the melting process. All compositions contained crystals in the as-quenched glass. All of the spinel based crystals present in the glasses were less than 10 μm in diameter, as determined by scanning electron microscopy with image analysis. Composition and temperature dependent models were generated using the resulting data and the best model fit was obtained by only considering spinel concentrations (R2 = 0.87). Two glasses were unable to be characterized because of an inability to process the glass under the conditions of this study. Those glasses were utilized to give insight into a potential multi-component constraint to aid in future statistical composition designs.

Synthesis of new transparent borate-based BaF2 nanocrystallized glass by formation of nucleation sites induced by rare earth ions

BaF2 nanocrystallized glasses were synthesized by heat-treatment of fluoroborate glasses, and highly transparent glass-ceramics were obtained with the addition of Er2O3. The crystal size decreased with increasing Er2O3 content: particle sizes of 25 and 5 nm were obtained for the non-doped and 1Er2O3-doped glass-ceramics, respectively. The nanocrystals dispersed homogeneously in the 1Er2O3-doped glass-ceramics, while the nanocrystals appeared to aggregate as particles with a size of ∼200 nm in the non-doped glass-ceramics. Upon continuous-wave laser excitation at 980 nm, both glass and glass-ceramics samples showed upconversion luminescence of Er3+. The shape of the spectrum of the glass resembles that of BaF2 crystal and the intensity was enhanced to ∼30 times the original intensity by crystallization. We proposed that fluoride-rich clusters were already established in the as-quenched glass, and the cluster paths acted act as the nucleation sites.