Stability Of Glasses Research Articles

Accelerated degradation of sealant/interconnect joint in solid oxide cell stacks

The electrical and microstructural stability of a model glass sealant sandwiched between two SS430 interconnects was investigated in terms of designed acceleration stress (AST) tests for 500 h in the air. Under applying different stressors, including DC voltage (0–35 V), inverse voltage cycles (3 and 4 cycles), and temperature (700–800 °C), morphological changes of anodically/cathodically polarized interfaces were studied. With 0.7 V and 750 °C, the specimen showed a stable electrical resistivity with well-bonded interfaces. Under higher voltages, a resistivity decay was observed with accelerated interfacial corrosion and delamination at the anode and roughening and losing contacts due to Si accumulation at the cathode side. With cyclic polarization, lower degradation in resistivity and less interfacial deterioration were observed. Aging at higher temperature was accompanied by a slight decrement in the resistivity.

Luminescence and photometric activity of an intense green emitting ZnBiBaBFTe:Tb3+ glasses

Borotellurite (ZnBiBaBFTe: ZnO + Bi2O3 + BaF2 + B2O3 + TeO2) glasses were fabricated by varying Tb2O3 concentration via the conventional melt and rapid quenching process. The glass stability (150 °C) and thermal stress (0.336) were evaluated using the differential thermal analysis. The rising value in the molar volume (39.69–43.86 cm3/mol) and field strengths (6.69–19.41 × 1015 cm−2) was due to the decrease in the density (2.932–2.804 gm/cm3) and inter-atomic distances (5.25 - 3.08 Å) of Tb3+ ions in ZnBiBaBFTe glasses. Measured excitation (PLE) and de-excitation (PL) spectra indicated that Tb3+:ZnBiBaBFTe glasses can be efficiently stimulated from 377 nm of UV radiation and exhibit a dazzle of green emission (543 nm) belonging to the transition 5D4→7F5 of Tb3+ ion. The radiative parameters of the level 5D4 of Tb3+ ion was predicted from the Ω2, 4, 6 intensity parameters by means of the JO (Judd-Ofelt) phenomenological formalism. Rise in Tb3+ concentration led to the enhancement of 5D4 emission transitions and reduction of lifetimes (2.24–1.82 ms) via dipole-dipole interaction. The detailed analysis of glasses revealed efficient lasing action parameters corresponds to branching ratio (> 60%), emission cross-section (14.61 × 10−22 cm2), gain bandwidth (15.34 × 10−28 cm3), and quantum efficiency (79%) along with photometric parameters like (x, y) color coordinates (∼0.29, 0.60), color purity (65%), and correlated color temperatures (∼6000 K) for green lasing applications.

Structural, thermal and optical studies of Eu3+ ion doped Ge22As20Se58 glass

The effect of Eu3+ doping on improving the amorphous nature of commercial chalcogenide glass/ChG (Ge22As20Se58), which is typically used as a molded lens for mid-infrared imaging, has been investigated. The observed absence of bright spots in Transmission Electron Microscope-Selected area (electron) diffraction (TEM-SAED) pattern confirmed the doping-induced amorphous nature of Eu-Ge22As20Se58 glass. The thermal studies over glass transition temperature (Tg) using DSC technique also revealed that Eu doping has increased the amorphous nature along with the thermal stability of Ge22As20Se58 glass. The optical analysis using UV–vis absorption spectroscopy showed that the activity of Eu-doped ChG has been extended across the UV-visible region. Tauc plot derived band gap energy of Eu-doped and undoped ChG is found to be 2.2 and 2.6 eV, respectively.

Observation of electrical threshold switching behavior and thermal crystallization in bulk Se86-xTe14Snx chalcogenide glasses

Selenium-rich chalcogenides have gained popularity as materials for selector devices due to their unique Ovonic Threshold Switching behavior. Bulk Se86-xTe14Snx glassy alloys (0 ≤ x ≤ 6) were prepared through the traditional melt quenching method. The samples with Sn atomic percentage (x) = 3 to 6 are found to exhibit a rapid and reversible transition between a highly resistive and conductive state affected by an electric field. A remarkable decrement in threshold voltage (Vth) from 453 V to 62 V has been observed with increase in the Tin content. Differential scanning calorimetry (DSC) analysis was carried out to understand the variation of Glass transition temperature (Tg), Crystallization temperature (Tc), and other important glass stability parameters and their compositional dependence. Se82Te14Sn4 sample was found to be thermally most stable with Herby’s parameter value (HR) of 0.3860 and a maximum number of switching cycles at room temperature. X-Ray diffraction patterns of annealed samples were compared with pristine glass to study the multi-phasic Se–Te–Sn alloy. Further, the threshold voltage (Vth) and the number of threshold switching cycles are found to decrease with an increase in temperature till crystallization on-set temperature (Toc). The temperature-dependent conductivity studies showed an abrupt increase in the conductivity of the samples as the temperature crossed the crystallization onset temperature.

Novel Ge-As-Se chalcogenide glass for potential high Brillouin gain coefficient of fiber

Two series of glasses compositions, xGeSe2-(100-x) As2Se3 (x = 15,42,63,79,94 mol%) and Ge30AsySe70-y (y = 4,10,15,20 mol%), were selected for optimization with a high Brillouin gain coefficient(gB) by considering both the acousto-optic parameters and the stability of glass against crystallization. The variation in its thermal, mechanical, and material acousto-optic properties were systematically investigated. In the xGeSe2-(100-x) As2Se3 series of glasses, the gradual increase of GeSe2, resulted in a significant increase in elastic modulus and longitudinal sound velocity (VL), whereas refractive index(n) and acoustic attenuation(α) decreased rapidly. The decrease in n, and the increase in VL were not conducive to the calculation of the gB. Furthermore, in the Ge30AsySe70-y series of glasses, n increased to a maximum of 2.62, and α decreased to a minimum of 215 dB/cm/GHz2, with increasing As content. The highest gB = 33.77 × 10−11m/W was obtained in Ge30As20Se50 at 1550 nm, and this value was ∼2.3 times greater than that obtained in As2S3 (gB = 14.43 × 10−11m/W) and ∼1.6 times greater than that obtained in As2Se3 (gB = 20.89 × 10−11m/W) chalcogenide (ChG) glass. On the basis of Ge30As20Se50 host glass, a chalcogenide single-refractive-index fiber was drawn with a lowest optical loss of 0.7 dB/m at 6.5 μm. The above results provided an important reference for the further development of new chalcogenide glass fiber with high gB, and broadened the application in Brillouin lasers.

The effect of metals on zeolite crystallization kinetics with relevance to nuclear waste glass corrosion

Geologic disposal of vitrified radioactive material is planned in several countries, but there are remaining uncertainties related to the long-term stability of glass exposed to groundwater. Specifically, the crystallization of aluminosilicate zeolite minerals can accelerate the rate at which glass corrodes and radioactive material is released into the biosphere. In this study, we identify elemental species that may accelerate or suppress zeolite formation using a protocol to examine their effects on zeolite synthesis over a three-day duration. Our results are consistent with previous works demonstrating glass corrosion acceleration in the presence of calcium. Furthermore, we identify two elements—tin and lithium—as inhibitors of zeolite P2 (gismondine, or GIS type) nucleation and, thus, promising components for promoting the long-term durability of glass waste forms.

Preparation, structure and luminescent properties of P2O5–Gd2O3–Ga2O3–NaF–ZnO glasses co-doped with Tb3+ and Sm3+

White light-emitting diodes have been intensively explored as a technique of green energy-conversion in recent decades. In this work, a unique Tb3+/Sm3+ co-doped P2O5–Gd2O3–Ga2O3–NaF–ZnO glass consisting of Q0, Q1 and Q2 units was successfully synthesized. The DSC curves demonstrated that the glass stability gradually deteriorated with the increase of Sm3+ contents. The emission spectra exhibited the energy transfer from Dy3+ to Tb3+ ions, and the energy transfer efficiency and probability grew monotonously with the increase of Sm3+ contents. With the help of temperature-dependent emission spectra, the glasses were validated to be thermally stable. The fluorescence curves and Inokuti-Hirayama model demonstrated that the dominant mechanism in the energy transfer process was electric dipole-quadrupole interaction. In addition. the white-light emission with suitable chromaticity coordinates and CCTs could be obtained by adjusting the contents of the sensitizer and activator for PGGNZ glasses. All investigations revealed the potential application of Tb3+/Sm3+ co-doped glasses in optical device applications.

Metal Organic Framework Glasses: A New Platform for Electrocatalysis?

Metal organic framework (MOF) glasses are a coordination network of metal nodes and organic ligands as an undercooled frozen-in liquid, and have therefore broadened the potential of MOF materials in the fundamental research and application scenarios. On the road to deploying MOF glasses as electrocatalysts, it remains several basic scientific hurdles although MOF glasses not only inherit the structural merits of MOFs but also endow with active catalytic features including concentrated defects, metal centers and disorder structure etc. The research on the ionic conductivity, catalytic stability and reactivity of MOF glasses has yielded scientific insights towards its electrocatalytic applications. Here, we first comb the history, definition and basic properties of MOF glasses. Then, we identify the main synthetic methods and characterization techniques. Finally, we advance the potentials and challenges of MOF glasses as electrocatalysts in furthering the understanding of these themes.

Microscopic observation of two-level systems in a metallic glass model.

The low-temperature quasi-universal behavior of amorphous solids has been attributed to the existence of spatially localized tunneling defects found in the low-energy regions of the potential energy landscape. Computational models of glasses can be studied to elucidate the microscopic nature of these defects. Recent simulation work has demonstrated the means of generating stable glassy configurations for models that mimic metallic glasses using the swap Monte Carlo algorithm. Building on these studies, we present an extensive exploration of the glassy metabasins of the potential energy landscape of a variant of the most widely used model of metallic glasses. We carefully identify tunneling defects and reveal their depletion with increased glass stability. The density of tunneling defects near the experimental glass transition temperature appears to be in good agreement with experimental measurements.

Glass formation and topology in relation to free volume, glass transition and band structure in Ge-Se-Sb chalcogenide system

The algebraic criterion for glass formation and glass stability has been discussed in terms of the mechanical threshold and physical parameters like mean bond energy and lone pair electrons of the Ge20Se80-xSbx (x = 0, 4, 8, 12, 16, 20) chalcogenide system. The topological parameter, mean coordination number (<r > ), has been correlated to the free volume percentage, glass transition temperature and theoretical bandgap of the system. Two approaches, namely, Manca's and Shimakawa's, have been used to calculate the theoretical bandgap. A stoichiometric composition at x = 16 has been predicted, and it is concluded that mechanical and chemical thresholds co-exist in the system and that the system is a potential candidate for IR applications.

Photoisomerization and local stability in molecular and polymer-network glasses

We explore the photo-response of azobenzene compositions in glassy epoxy matrices, finding that the response time of individual azobenzenes is distributed according to a power law, where the median response can be tuned by both azobenzene chemistry and matrix properties.

Enhancing proton mobility and thermal stability in phosphate glasses with WO3: the mixed glass former effect in proton conducting glasses.

This study aimed to investigate the impact of WO3 on the thermal stability of glass, as measured by the glass transition temperature (Tg), as well as the activation energy (Ea) of proton conduction and proton mobility (μH). These parameters were analyzed based on variations in the glass network structure and the nature of the P-O and O-H bonds in 35HO1/2-xWO3-8NbO5/2-5LaO3/2-(52 - x) PO5/2 (x = 2, 4, 6, and 8) glasses. As previously predicted by a linear regression model, replacing PO5/2 with WO3 resulted in an increase in Tg and μH at Tg. The observed enhancement rates were +9.1 °C per mol% of WO3 for Tg and 0.09 per mol% of WO3 for log(μH at Tg [cm2 V-1 s-1]), which aligned with the predicted values of +6.5 °C and 0.08, respectively, validating the linear regression model. The increased Tg was attributed to the formation of heteroatomic P-O-W linkages that tightly cross-linked the phosphate chains. The decrease in Ea and increase in μH at Tg with increasing WO3 content were attributed to the reduction of the energy barrier for inter-phosphate chain proton migration owing to the increasing proton migration paths through P-O-W linkages. This μH enhancement is distinct from previously reported ones due to the reduction of the energy barrier for proton dissociation from OH groups. This phenomenon can be attributed to the mixed glass former effect in proton conducting glass.

Effect of BaO/TeO2 oxide ratio in TiO2.B2O3.Fe2O3 glasses: Physical, thermal and optical absorption studies

Glasses of the composition xBaO-(30-x)TeO2-10TiO2-59.5B2O3-0.5Fe2O3 were synthesized using the melt-quenching process and investigated using differential scanning calorimeter (DSC), optical characterization techniques. The DSC spectra of the prepared glass samples attest to their glassy nature. Archimedes' principle was used to determine the density (ρ) of the glass samples. The progressive replacement of BaO with TeO2 leads to the structural compactness of the vitreous network and improves the glass stability. Optical absorption spectra have also been employed to examine the optical transitions and electronic band structure. From the edges of UV absorption, the Eopt and Urbach energies have been determined. All the glasses' physical properties have been examined in relation to BaO mol%.

Effect of B&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Content on Structure and Properties in High Refractive Index BaO-ZnO-TiO&lt;sub&gt;2&lt;/sub&gt;-SiO&lt;sub&gt;2&lt;/sub&gt; Glass System

In this paper, BaO-ZnO-TiO2-SiO2 is used as the research system of high refractive index glass, and IR, XRD and DTA are used to study the structure, thermal behavior, crystallization and chemical stability of different glasses when B2O3 gradually replaces SiO2. The results show that when B2O3 replaces SiO2, glass still has an amorphous structure, and the density of glass shows a decreasing trend with the increase of B2O3 content. With the increase of B2O3 content, the boron-oxygen tetrahedron gradually transforms into the boron-oxygen triangle, which makes the overall crystallization of the glass structure weaken. The results show that the density, refractive index and water resistance of glass beads without B2O3 are the best. With the increase of B2O3 content, the activation energy of crystallization decreases, the potential barrier to be overcome for crystallization decreases, as the same time the phenomenon of glass crystallization is obvious. Keywords:High refractive index glass; BaO-ZnO-TiO2-SiO2; Crystallization; Chemical stability

Effect of Al(PO3)3, NaF, and SrF2 on structure and properties of fluorophosphate glass

The thermal stability and structural evolution of (55-x-y)Al(PO3)3-xNaF-8MgF2-10CaF2-ySrF2-17BaF2-10LiF (mol%) glasses were investigated. The thermal stability of the fluorophosphate glass system was characterized by DSC. As the content of metaphosphate increased, the thermal stability was strengthened. Besides, the thermal stability reached the strongest at alkaline metal and alkaline earth metal fluoride contents converged. On the one hand, according to Raman and FT-IR spectra, it was demonstrated that the intensity of OPO vibration in the glass structure was strengthened with the increase of Al (PO3)3 and NaF. On the other hand, 31P NMR results indicated that the POP bond was also enhancing when the Al (PO3)3 content increased. In summary, OPO and POP bonds were components of [PO4] units, and their increase signified that the structural stability of glass was enhanced. During the process of expanding the content of Al(PO3)3, deconvolution of O 1s and F 1s in XPS spectrum revealed that the increase of PO and FP bond content resulted in the structural distortion of polyhedral P[O, F]4 in glass structure and enhanced the disorder of glass.

Effect on structure, stability, and H+ irradiation on Nd3+/Ru4+‐loaded iron phosphate glass for nuclear applications

AbstractNuclear energy generation technology is critically linked with the safe disposal of radioactive waste. In this context, iron phosphate glass (IPG) is gaining predominance as nuclear waste vitrification matrix that necessitates a thorough study on the effect of the loading of various nuclear fission waste materials in it. In this study, the effect of the loading of Nd3+ (which acts as a surrogate for radioactive curium (Cm)) and Ru4+ (which is a fission product of 235U) in IPG has been assessed. The optimum loading of Nd3+/Ru4+ leading to the formation of homogenous melt has been ascertained via powder X‐ray diffraction and scanning electron microscopy techniques. The modification in the Fe3+/Fe2+ ratio in IPG and the consequent change in its average coordination number with Nd3+/Ru4+ loading has been deduced from the Mössbauer studies. Local structure analysis has been done using X‐ray absorption spectroscopy at Nd/Ru/Fe K‐edge (as applicable) for all the single and co‐loaded IPG samples. All the co‐loaded samples show enhanced glass stability and glass forming ability compared to unloaded IPG which has been ascertained via detailed thermal studies. The variation in IPG network structure on the addition of Nd2O3 and RuO2 has been ascertained through spectroscopic techniques like Fourier transform infrared (FTIR) and Raman. The base glass and a few representative homogenous single and co‐loaded IPG samples have been irradiated with 4.5 MeV proton beam to simulate the hosting of radioactive elements and the radiation effect on glass structure has been ascertained using FTIR and Raman spectroscopies. The suitability of IPG as nuclear waste vitrification matrix for Nd3+ and Ru4+ is established through all the above analyses.

Structure, crystallization behavior and chemical stability analysis of Nd3+-basaltic glasses for immobilizing simulated trivalent actinides

The Nd3+-basaltic glass was prepared by melt-heat treatment method using Nd3+ to simulate trivalent actinides. The structure, thermal stability and leaching characteristics of basaltic glass with different contents of Nd2O3 were investigated. XRD and SEM-EDX results show that the simulated waste loading of Nd2O3 in basaltic glass can be up to ∼30 wt.%, and oxy-silicate apatite (Ca2Nd8(SiO4)6O2) precipitates when Nd2O3 content reaches 32 wt.%. Raman results indicate that the addition of Nd2O3 breaks some of Si-O-Si bond, but overall there is not much effect on the glass network structure. DSC results show the Tg of the glasses increases and the thermal stability first increases and then decreases with the increase of Nd2O3 content. The leaching resistance of samples was evaluated by the ASTM Product Consistency Test (PCT) Method, which shows that all the samples have good leaching resistance. Among them, the standard mass loss of Na is the greatest after 28 days. The NLNd is 4∼5 orders of magnitude lower than other elements.

Solid Electrolyte Membranes Based on Li2O-Al2O3-GeO2-SiO2-P2O5 Glasses for All-Solid State Batteries.

Rechargeable Li-metal/Li-ion all-solid-state batteries due to their high safety levels and high energy densities are in great demand for different applications ranging from portable electronic devices to energy storage systems, especially for the production of electric vehicles. The Li1.5Al0.5Ge1.5(PO4)3 (LAGP) solid electrolyte remains highly attractive because of its high ionic conductivity at room temperature, and thermal stability and chemical compatibility with electrode materials. The possibility of LAGP production by the glass-ceramic method makes it possible to achieve higher total lithium-ion conductivity and a compact microstructure of the electrolyte membrane compared to the ceramic one. Therefore, the crystallization kinetics investigations of the initial glass are of great practical importance. The present study is devoted to the parent glasses for the production of Li1.5+xAl0.5Ge1.5SixP3-xO12 glass-ceramics. The glass transition temperature Tg is determined by DSC and dilatometry. It is found that Tg decreases from 523.4 (x = 0) to 460 °C (x = 0.5). The thermal stability of glasses increases from 111.1 (x = 0) to 188.9 °C (x = 0.3). The crystallization activation energy of Si-doped glasses calculated by the Kissinger model is lower compared to that of Si-free glasses, so glass-ceramics can be produced at lower temperatures. The conductivity of the glasses increases with the growth of x content.

Description of non-isothermal crystallization kinetics of Fe48Co32P14B6 metallic glass using the isothermal analysis data

The non-isothermal crystallization kinetics of Fe48Co32P14B6 glass was experimentally studied by differential scanning calorimetry (DSC) at heating rates from 5 to 40 K/min. The integral form of the non-isothermal glass crystallization kinetic equation based on the combination of the Kolmogorov's model of mass crystallization kinetics and the Kashchiev's transient nucleation approach involving the classical equations for nucleation rate and growth velocity was derived. The kinetic model describing the interface-controlled mode of crystallization in a wide range of the nucleation rate deviations from its steady-state value involves only the first terms of the Kashchiev's infinite series and of the series obtained by re-summation. Using the thermodynamic and kinetic parameters and their temperature dependencies derived from analysis of the isothermal crystallization of the glass investigated [Vasiliev et al, J. Alloys and Compds. 869 (2021) 159,285] the experimental DSC scans were correctly approximated in the frames of the proposed kinetic model. The values of the transient of nucleation rates at continuous heating were estimated and the effect of non-stationarity on thermal stability of metallic glasses was discussed.

Designing Glass and Crystalline Phases of Metal-Bis(acetamide) Networks to Promote High Optical Contrast.

Owing to their high tunability and predictable structures, metal-organic materials offer a powerful platform to study glass formation and crystallization processes and to design glasses with unique properties. Here, we report a novel series of glass-forming metal-ethylenebis(acetamide) networks that undergo reversible glass and crystallization transitions below 200 °C. The glass-transition temperatures, crystallization kinetics, and glass stability of these materials are readily tunable, either by synthetic modification or by liquid-phase blending, to form binary glasses. Pair distribution function (PDF) analysis reveals extended structural correlations in both single and binary metal-bis(acetamide) glasses and highlights the important role of metal-metal correlations during structural evolution across glass-crystal transitions. Notably, the glass and crystalline phases of a Co-ethylenebis(acetamide) binary network feature a large reflectivity contrast ratio of 4.8 that results from changes in the local coordination environment around Co centers. These results provide new insights into glass-crystal transitions in metal-organic materials and have exciting implications for optical switching, rewritable data storage, and functional glass ceramics.