Stability Of Glasses Research Articles

Ionic conductivity and thermal stability of Li2O–Li2S–P2S5 oxysulfide glass

Sulfide-based solid electrolytes exhibit high ionic conductivities of more than 10−4 S cm−1 at room temperature. However, sulfide electrolytes have a major disadvantage because they are hygroscopic. To reduce costs and develop practical all-solid-state batteries, it is imperative to enhance their chemical stability in air. In this study, Li2O is added to 75Li2S·25P2S5 glasses to improve their chemical stability to moisture in air, and (75 − x)Li2S·25P2S5·xLi2O samples are synthesized. The effects of the addition of Li2O on the electrical properties and thermal behavior of 75Li2S·25P2S5 glasses are examined. With an increase in the Li2O content, the crystallization temperature of 75Li2S·25P2S5 glasses shifts to the high-temperature side, and the glass phase stabilizes over a wide temperature range. Specifically, the substitution of Li2O with Li2S enhances the thermal stability of glasses. This is attributed to the change in the precipitated crystalline phase, β-Li3PS4 (x = 0, 5) → thio-LISICON III Li3.2P0.96S4 (x = 10, 15). In addition, the (75 − x)Li2S·25P2S5·xLi2O glass ceramics for x = 15 exhibit higher conductivity than pristine glasses because of the thio-LISICON III Li3.2P0.96S4 crystalline phase. Thus, the addition of more than 10 mol% of Li2O ensures a good balance between thermal stability, atmospheric stability, and conductivity.

Structural and thermal behavior of 45S5 Bioglass®‐based compositions containing alumina and strontium

AbstractThe present research exposes the influence of 2 mol% of Al2O3 and 2 mol% SrO in 45S5 Bioglass®‐based compositions. Four compositions were produced to elucidate the difference in how both oxides influence structure and thermal behavior separately and their synergy when together. Thermal properties, crystallization tendency, and sintering behavior was evaluated by differential scanning calorimetry, hot stage microscopy, and dilatometry. Changes of medium‐range structures were characterized by Qn distribution of Raman spectroscopy and evaluation of 31P, 27Al, 23Na, and 29Si environment obtained by magic angle spinning nuclear magnetic resonance. Despite Qn distribution was predominantly Q2 in all samples, the composition criteria used enabled improved processing and stabilibity characteristics. The addition of Al2O3 and SrO promoted larger sinterability parameter (Sc) which indicates better sintering behavior, the glass stability against crystallization doubled (KH) compared to 45S5 and the processing window enlarged from 106 to 171.

Brittle yielding of amorphous solids at finite shear rates

Amorphous solids display a ductile to brittle transition as the kinetic stability of the quiescent glass is increased, which leads to a material failure controlled by the sudden emergence of a macroscopic shear band in quasi-static protocols. We numerically study how finite deformation rates influence ductile and brittle yielding behaviors using model glasses in two and three spatial dimensions. We find that a finite shear rate systematically enhances the stress overshoot of poorly-annealed systems, without necessarily producing shear bands. For well-annealed systems, the non-equilibrium discontinuous yielding transition is smeared out by finite shear rates and it is accompanied by the emergence of multiple shear bands that have been also reported in metallic glass experiments. We show that the typical size of the bands and the distance between them increases algebraically with the inverse shear rate. We provide a dynamic scaling argument for the corresponding lengthscale, based on the competition between the deformation rate and the propagation time of the shear bands.

Phase-separation engineering in fluorozirconate glass for designing and fabricating of transparent perfluorinate glass ceramic

Perfluorinate glass ceramics with ultra-low phonon energy are very important optical and photonic materials. Unfortunately, there is no suitable method to obtain transparent perfluorinate glass ceramics due to poor thermal stability of fluoride glass. As a result, wide applications of glass ceramics in advanced infrared systems are restricted. Here, an effective method based on phase-separation engineering is used to develop transparent perfluorinate glass ceramics. In this article, a novel transparent Er3+-doped ZnZrF6-Ba6Zn7F26 perfluorinate glass ceramic was designed and fabricated by phase-separation engineering. The sample exhibits low phonon energy (564 cm−1), ultra-wide transmission range (0.33–8.2 μm, T ≥ 50 %), and strong infrared emission, which is better than that of ZBLAN glass, oxide-, and oxyfluoride-glass ceramics. These good properties of the perfluorinate glass ceramic demonstrate that phase-separation engineering not only offers an effective approach to obtain perfluorinate glass ceramics but also provides wide-ranging opportunities for advanced infrared optical and photonic materials.

Crystallization tendency of APIs possessing different thermal and glass related properties in amorphous solid dispersions.

The correlation between glass forming ability (GFA) and several thermophysical or physicochemical properties of APIs with the formation and the physical stability of amorphous solid dispersions (ASDs) was evaluated in the present study. Eight poorly water-soluble APIs belonging in different GFA classes (i.e. a) GFA Class I: Carbamazepine, CBZ, b) GFA Class II: Agomelatine, AGO, Aprepitant, APT, Rivaroxaban, RIV, and c) GFA Class III: Indomethacin, IND, Pioglitazone, PIO, Piroxixam, PIR, and Simvastatin, SIM) were tested, in addition to six commonly used matrix-carriers (namely povidone, PVP, hydroxypropyl cellulose, HPC-SL, copovidone, coPVP, Soluplus®, SOL, and gelatin) in order to prepared ASDs via film casting approach. Results using polarized light microscopy (PLM) showed a similar drug crystallization tendency from ASDs independently of their GFA classification, glass stability or glass fragility. X-ray diffraction analysis verified the formation and the physical stability of ASD (independently of GFA class) when a suitable matrix-carrier was selected (i.e. SOL for AGO, RIV and SIM, PVP for APT, CBZ and IND, coPVP for PIO and gelatin for PIR). Further attempts to correlate some physicochemical properties (i.e. component's binding affinity and miscibility) with the formation and the crystallization tendency of the prepared ASDs showed no apparent correlation in regards to the different drug GFA classes. Finally, the evaluation of molecular interactions via FTIR analysis also failed to adequately distinguish the differences in regards to the formation and the physical stability of the prepared systems.

Creep behaviors of Ta-alloyed Cuzr-Based metallic glass composite

In the current work, the tensile creep behaviors of a (Cu0.5Zr0.5)92Ta8 metallic glass composite were investigated. The precipitates and the metallic glass matrix in the as-spun ribbons have nearly same compositions. The addition of Ta element enhances the thermal stability of binary Cu50Zr50 metallic glass. The apparent activation energies of tensile creep increase with the applied stress, and the values of strain rate sensitivity decrease from 0.39 to 0.16 with the increasing applied temperatures. The correlationship of activation energy and activation volume suggests that the largest activation energy corresponds to the smallest activation volume, and vice versa. The values of strain rate sensitivity are noticeably smaller than reported values, which is related to the softening of (Cu0.5Zr0.5)92Ta8 ribbons with the increasing creep temperatures.

Effect of molybdenum on structural features and thermal properties of iron phosphate glasses and boron-doped iron phosphate glasses

The variations of structure and thermal properties in iron phosphate glasses and boron-doped iron phosphate glasses due to MoO3 addition up to 50 mol% were investigated and compared in detail. The results show that MoO3 depolymerizes the phosphate networks resulting in a higher connectivity of the networks through [MoO4] units and the formation of Mo–O–P bonds diversifies the cross-linking of the glass networks, leading to the conversion of long phosphate chains to pyrophosphate units and/or orthophosphate units. These structure variations cause the decrease of glass transition temperature, thermal stability and glass formation ability of iron phosphate glasses. Moreover, the MoO3 loading, thermal stability and glass formation ability of iron phosphate glasses were improved by boron. The reasons on the improved properties are also explained and analyzed. The obtained conclusions provide researchers with the role of Mo in structure and properties of phosphate glasses for Mo containing nuclear waste immobilization.

Crystallization Mechanism in Spark Plasma Sintered Bulk Metallic Glass Analyzed using Small Angle Neutron Scattering

Understanding the thermal stability of metallic glasses is critical to determining their safe temperatures of service. In this paper, the crystallization mechanism in spark plasma sintered Fe48Cr15Mo14Y2C15B6 metallic glass is established by analyzing the crystal size distribution using x-ray diffraction, transmission electron microscopy and in-situ small angle neutron scattering. Isothermal annealing at 700 °C and 725 °C for 100 min resulted in the formation of (Fe,Cr)23C6 crystals, measured from transmission electron micrographs, to be from 10 to 30 nm. The small angle neutron scattering intensity measured in-situ, over a Q-range of 0.02 to 0.3 Å−1, during isothermal annealing of the sintered samples, confirmed the presence of (Fe,Cr)23C6 crystals. The measured scattering intensity, fitted by the maximum entropy model, over the Q-range of 0.02 to 0.06 Å−1, revealed that the crystals had radii ranging from 3 to 18 nm. The total volume fraction of crystals were estimated to be 0.13 and 0.22 upon isothermal annealing at 700 °C and 725 °C for 100 min respectively. The mechanism of crystallization in this spark plasma sintered iron based metallic glass was established to be from pre-existing nuclei as confirmed by Avrami exponents of 0.25 ± 0.01 and 0.39 ± 0.01 at the aforesaid temperatures.

Dielectric and optical properties of glasses and glass-ceramics synthesized from agro-food wastes

In this study, glasses and glass-ceramics are prepared using agro-food wastes instead of conventional mineral oxides like SiO2, CaO, and Na2O, etc. X-ray diffraction (XRD) technique is used to check the amorphous and crystalline nature of the as-quenched and heat-treated samples, respectively. X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) are used to evaluate the chemical composition of the as-quenched samples. Thermal properties of the glasses such as thermal stability and characteristic temperature of glasses are evaluated using differential gravimetric analyser (TGA) and differential scanning calorimetry (DSC), respectively. Optical band gap (Eg) and dielectric constant of the samples are found ~3.26–3.57 eV and 10–32 range at room temperature (RT), respectively. Most of the properties of the agro-food wastes derived glasses are comparable and better than glasses synthesized using minerals oxides. These glasses and glass-ceramics may find applications in the microelectronic, glass sealants in the solid oxide fuel cells (SOFCs).

A Lithium Oxythioborosilicate Solid Electrolyte Glass with Superionic Conductivity

AbstractAs potential next‐generation energy storage devices, solid‐state lithium batteries require highly functional solid state electrolytes. Recent research is primarily focused on crystalline materials, while amorphous materials offer advantages by eliminating problematic grain boundaries that can limit ion transport and trigger dendritic growth at the Li anode. However, simultaneously achieving high conductivity and stability in glasses is a challenge. New quaternary superionic lithium oxythioborate glasses are reported that exhibit high ion conductivity up to 2 mS cm−1 despite relatively high oxygen: sulfur ratios of more than 1:2, that exhibit greatly reduced H2S evolution upon exposure to air compared to Li7P3S11. These monolithic glasses are prepared from vitreous melts without ball‐milling and exhibit no discernable XRD pattern. Solid‐state NMR studies elucidate the structural entities that comprise the local glass structure which dictates fast ion conduction. Stripping/plating onto lithium metal results in very low polarization at a current density of 0.1 mA cm−2 over repeated cycling. Evaluation of the optimal glass composition as an electrolyte in an all‐solid‐state battery shows it exhibits excellent cycling stability and maintains near theoretical capacity for over 130 cycles at room temperature with Coulombic efficiency close to 99.9%, opening up new avenues of exploration for these quaternary compositions.

Factors influencing the metallic glass formation in alloy systems

Several criteria are available in literature for selection of alloy compositions for metallic glasses. We have analyzed characteristics of glass-forming compositions numbering around 1000 in terms of three parameters. They refer toelectron to atom ratio (e/a), volume ratio (VR) and radius ratio (RR). Venn-Diagrams created based on these parameters for Fe-, Cu-, Zr-, Ti-, La-, Mg-, Co-, Al-, Ni- and Pd-based alloy systems will be presented. Relative importance of e/a, VR, and RR will be indicated. Having done this, we would like to understand the process of stabilization of Bulk Metallic Glasses (BMGs) in terms of Fermi surface (FS) and Pseudo Brillioun zone (PBZ) interaction.

Thermal stability and crystallization of a Zr-based metallic glass produced by suction casting and selective laser melting

The thermal stability and crystallization mechanism of the Zr59.3Cu28.8Al10.4Nb1.5 (at%) metallic glass produced through selective laser melting SLM (from industrial grade material) was studied and compared with the same alloy produced by suction casting (from laboratory grade material of high purity). Oxygen- and Al-rich particles of a cubic phase (Fd3‾m) with a size of up to 200 nm are detected in the as-built selective laser melted samples by transmission electron microscopy.The crystallization process of the cast and SLM samples is investigated by in-situ X-ray diffraction experiments. In the cast samples, the initial crystallization occurs via the formation of a metastable tetragonal phase (Al2Zr3), together with tetragonal CuZr2 and hexagonal Al3Zr4 type structures, while the SLM samples initially crystallize through the formation of the metastable, oxygen- and Al-rich, cubic phase already present before annealing. The main phases present at the end of the crystallization for both type of samples are the same, mainly CuZr2 and Al3Zr4. The differences in the crystallization paths are attributed to differences in the oxygen levels. In general, the higher oxygen content (∼1 at%) of the SLM samples results in a decrease of the thermal stability of the alloy and promotes the formation of an oxygen-rich, metastable cubic phase.

Influence of Annealing in the Close Vicinity of Tg on the Reorganization within Dimers and Its Impact on the Crystallization Kinetics of Gemfibrozil.

In this paper, broadband dielectric spectroscopy (BDS) has been applied to study the molecular dynamics and crystallization kinetics of the antihyperlipidemic active pharmaceutical ingredient (API), gemfibrozil (GEM), as well as its deuterated (dGEM) and methylated (metGEM) derivatives, characterized by different types and strengths of intermolecular interactions. Moreover, calorimetric and infrared measurements have been carried out to characterize the thermal properties of examined samples and to probe a change in the H-bonding pattern in GEM, respectively. We found that the dielectric spectra of all examined compounds, collected below the glass transition temperature (Tg), reveal the presence of two secondary relaxations (β, γ). According to the coupling model (CM) predictions, it was assumed that the slower process (β) is of JG type, whereas the faster one (γ) has an intramolecular origin. Interestingly, the extensive crystallization kinetics measurements performed after applying two paths, i.e., the standard procedure (cooling and subsequently heating up to the appropriate temperature, Tc), as well as annealing at two temperatures in the vicinity of Tg and further heating up to Tc, showed that the annealing increases the crystallization rate in the case of native API, while the thermal history of the sample has no significant impact on the pace of this process in the two derivatives of GEM. Analysis of the dielectric strength (Δε) of the α-process during annealing, together with the results of Fourier transform infrared spectroscopy (FTIR) measurements, suggested that the reorganization within dimeric structures formed between the GEM molecules is responsible for the observed behavior. Importantly, our results differ from those obtained by Tominaka et al. (TominakaS.; KawakamiK.; FukushimaM.; MiyazakiA.Physical Stabilization of Pharmaceutical Glasses Based on Hydrogen Bond Reorganization under Sub-Tg TemperatureMol. Pharm.20171426427310.1021/acs.molpharmaceut.6b00866.28043129), who demonstrated that the sub-Tg annealing of ritonavir (RTV), which is able to form extensive supramolecular hydrogen bonds, protects this active substance against crystallization. Therefore, based on these contradictory reports, one can hypothesize that materials forming H-bonded structures, characterized by varying architecture, may behave differently after annealing in the vicinity of the glass transition temperature.

Radiation stability study on cerium loaded iron phosphate glasses by ion irradiation method

To study radiation stability of iron phosphate glasses, cerium is used as surrogate of actinides. Cerium doped iron phosphate glasses have been synthesised. Heavy gold ion irradiations have been performed on pure and cerium doped iron phosphate glasses to mimic ballistic damage due to cascade of recoil atoms. Pure and cerium doped glasses are irradiated with gold ions of energy 750 keV at fluence of 2 × 1015 ions/cm2. In this paper, ion irradiation effects on glass network modification and change in speciation of network former have been discussed. Significant changes in glass network structure and speciation of network former is observed.

Thermal and optical properties of binary magnesium tellurite glasses and their link to the glass structure

Binary magnesium tellurite glasses x MgO, (100-x) TeO2, studied to determine their glass forming range, structure, thermal and optical properties. Glasses were successfully synthesis in the range x = 10–45 mol%. Addition of 50 mol% of MgO leads to the appearance of the Mg3TeO6 crystalline phase. The molar volume decreases linearly with increasing MgO content. Both glass transition and crystallization temperature increase with increasing MgO content. The deduced glass stabilities show a slight maximum for x = 25 and 30mol%. Studying the structure of these glasses using Raman spectroscopy reveals the transformation of trigonal bipyramid TeO4 (tbp) structural unit to the trigonal pyramid TeO3 units with the intermediate phase TeO3+1. The coordination of Te–O decreases with increasing MgO content. The UV–Vis spectra show a shift of the UV-cutoff toward higher energy and the measured refractive index decreases with increasing MgO. Optical band gap was estimated and the obtained values were used to calculate molar refractivity, molar polarizability and a calculated refractive index. The metallization criterion is found in the range (0.399–0.417) indicating good optical nonlinearity of the prepared glasses.

Эффективные коэффициенты диффузии и термическая устойчивость структуры металлического стекла Fe-=SUB=-48-=/SUB=-Co-=SUB=-32-=/SUB=-P-=SUB=-14-=/SUB=-B-=SUB=-6-=/SUB=-

The values of linear growth velocities of the eutectic colonies in the temperature range of 679–717 K have been determined for the first time from the electron microscopic studies of the partially crystallized samples of Fe48Co32P14B6 metallic glass. Using these data, the values of the effective diffusion coefficients governing growth have been calculated. It has been established that the temperature dependence of the effective diffusivity in Fe48Co32P14B6 glass is well approximated by an Arrhenius law and their values in the temperature range of crystallization are about 2–3 orders of magnitude smaller than those in the Fe40Ni40P14B6 commercial glass. The values of the effective diffusion coefficients at the onset crystallization temperature have been determined, the correlation between pre-exponential factors and activation energies has been found. It has been shown that the parameters which characterize the effective diffusivity in the glass investigated are in good agreement with the published data for the eutectically crystallizing metallic glasses. It has been established that the physical reason of the enhanced thermal stability of the FeCo-based glass compared with that of Fe40Ni40P14B6 is the lower atomic mobility at the glass/crystal interface.

Correlation between bioactivity and thermodynamic stability of glasses of the molar formula 20.15[(2.038 + x)SiO<sub>2</sub>-(1.457 - x)Na<sub>2</sub>O]-2.6P<sub>2</sub>O<sub>5</sub>-25.73CaO-1.22MgO

The purpose of this study is to establish the influence of composition on the glass transition temperature, density, enthalpy of dissolution in an acid bath and bioactivity in glasses of the molar formula 20.15[(2.038 + x)SiO2-(1.457 − x)Na2O]-2.6P2O5-25.73CaO-1.22MgO. It is also a question of correlating bioactivity and stability in this oxide glass system. Nine samples were prepared by high temperature melting followed by quenching. These samples were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), dissolution calorimetry and pycnometry. Their bioactivity was estimated using the Anderson model. The results indicate that the effect of magnesium composition can lead to a decrease in the glass transition temperature (Tg). These results also show that a decrease in glass stability leads to a decrease in bioactivity.

Structural properties of Ag-Er3+doped Tungsten Tellurite Glass Ceramics

Tellurite based glasses of composition TeO2-WO3- Li2O-Yb2O3- Er2O3 with different Ag2O (TWLEYA) concentrations has been prepared by melt quenching technique. Heat-treatment process of glass samples was performed to nucleate Ag-NPs and glass-ceramic nature of samples is evidenced by XRD measurement. For glass stability of transition temperature and onset crystallization of this glass, the system has been studied by DSC. Surface plasmon-enhanced photoluminescence in the glasses are measured in the range 535-550 nm green and 640-650nm red under 488nm excitation. Raman spectrum revealed glasses were mainly formed by the [TeO4], {TeO3}, [WO4] and [WO6] units and [TeO4] units convert to [TeO3] units with the addition of WO3 and Li2O into tellurite glasses. The result indicates that enhancement of Raman intensity and a small shift has been grown due to surface plasmon of 12hrs heat-treated Ag nanoparticle doped TWLEYA glass. Thus enhanced optical response of the glass samples with Ag-NPs is attributed to the growth of the local field and vicinity of the nanoparticles on erbium ions. With optimum 0.7 mol%, Ag NPs in TWLEYA glass may be utilized for their potential applications in photonic devices

Glass engineering of aminotriazine-based materials with sub-ambient Tg and high kinetic stability

Designing molecular glasses with phenyl rings favors a lower Tg and higher glass stability compared to cyclohexyl analogues.

Optical and spectroscopic properties of Ho3+-doped fluorophosphate glasses for visible lighting applications

Holmium (Ho3+)-doped fluorophosphate glasses (P2O5–BaF2–CaF2–TiO2–Ho2O3, PCfBfTiH) were fabricated by melt-quenching technique. The glass transition (548 °C) and crystallization (577 °C) temperatures and glass stability factor (161 °C) were obtained from DSC analysis. Judd-Ofelt (JO) intensity parameters (Ω2, Ω4 and Ω6) of PCfBfTiH15 glass were evaluated. Intense green (545 nm) emission was obtained for the 5S2 + 5F4 → 5I8 transition upon excitation of 451 nm. The stimulated emission cross-section (σem) of PCfBfTiH15 glass was found to be as high as 2.01 × 10−20 cm2. Decay curves of the 5S2 + 5F4 → 5I8 transition were analyzed by double exponential function. High lifetime of 11.29 μs for the 5S2 + 5F4 level was obtained. The CIE chromaticity coordinates for the emission spectra were professed that the green emission owing to the 5S2 + 5F4 → 5I8 transition may be useful for laser and display applications at around 545 nm.