Glass Crystallization Research Articles

Effect of manganese on the structure of CMAS slag glass–ceramics

With the acceleration of industrialization, environmental issues have received great attention from governments and societies around the world. Utilizing solid wastes containing valuable heavy metals and exploring their role and application in materials is one of the focal issues of environmental protection in recent years. In this paper, in order to explore the effect of Mn content on the crystallization of CaO-MgO-Al2O3-SiO2 glass–ceramics, glass–ceramics with different content of MnO2 were prepared by sintering method and the effect of MnO2 doping on the crystalline properties, glass stability and heavy metal fixation properties of the stainless steel slag glass–ceramics was investigated by differential scanning calorimetry (DSC), Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscope (SEM). The analysis using crystallization kinetics showed that surface crystallization dominated the whole crystallization process in the range of 0% to 10% MnO2 content. The peak glass crystallization and depolymerisation temperatures of the glass–ceramics increased gradually with increasing MnO2 content, and the main crystallization mode of the samples was one-dimensional crystallization. The main crystalline phase of the resulting glass–ceramics was transformed from diopside to spinel, with a crystallization temperature of 860℃. Heavy metals solidified in the spinel phase. This study shows that heavy metals can be effectively immobilized in glass–ceramics. In summary, the use of solid waste to prepare final products with good environmental performance provides a feasible way to utilize solid waste resources.

Correlation of low field nuclear magnetic resonance relaxation with composition and glass transition of hard candies

Hard candies produced from sucrose and doctoring agents such as glucose syrup (GS) and high fructose corn syrup (FS) have been investigated in terms of their final composition, glass transition temperature (Tg), degree of crystallinity, total soluble solids (TSS) content and water activity (aw). Time domain (TD) 1H NMR longitudinal relaxation time (T1) and second moment (M2) measurements have been used to understand the glassy state and crystallization characteristics for different hard candy formulations. The investigated candies include sucrose as the main sugar component. Different levels of doctoring agents have been mixed with sucrose to obtain products with different characteristics. It has been shown that addition of any doctoring agent to sucrose formulations decreases the Tg of the system significantly (p≤ 0.05). Furthermore, GS or FS addition also induce significant changes in TSS and aw. T1 and M2 results are almost parallel to each other, both reaching the highest values for the highest sucrose concentration (p≤ 0.05). The results demonstrate that the glass transition and crystallization characteristics of hard candy formulations can be monitored and analyzed by TD NMR relaxometry, alternative to other frequently used conventional methods including differential scanning calorimetry (DSC) and X-ray diffraction.

Crystallization and mechanical properties of a barium titanosilicate glass

Crystallization and mechanical properties of a barium titanosilicate glass

Highly sensitive refractive index sensing with a dual-band optically transparent ITO-based perfect metamaterial absorber for biomedical applications

In this paper, a dual-band optically transparent square-shaped perfect metamaterial absorber operating in the frequency range from 2 to 4 terahertz (THz) is proposed. The structure consists of an indium tin oxide (ITO)-based split ring resonator (SRR) structure with additional splits and rectangular inner strips to form the top layer over the lead glass substrate. Perfect absorption is attained in the frequencies of 2.089 and 3.892 THz with absorbances of 99.99% and 99.98% in TE polarization mode, respectively. Perfect absorption is also achieved in TM polarization mode at 2.23 THz. Broadband absorption is found in TM polarization mode with full width half maximum (FWHM) of 1.1742. The proposed structure has one polarization-insensitive band in TE polarization mode. Absorbance is greater than 80% and 90% in the successive absorption peaks even at 60° and 75° of incidence, respectively. The resonance frequency is sensitive to the refractive index of the medium. As a result, the proposed metamaterial structure may be implemented as a refractive index (RI) sensor with a high sensitivity of 1109 GHz/RIU and 1954 GHz/RIU in both absorption bands for a refractive index range of 1.34 to 1.40. It's interesting to note that the refractive index of most biological samples ranges from 1.3 to 1.39. The figure of merit (FOM) of the proposed sensor can reach as high as 10 and 14 for the 1st and 2nd frequency bands. As a result, the proposed sensor has a high sensitivity and can be employed in medical applications. Potential applications of the proposed absorber include imaging, biomedical sensing, etc.

The influence of phosphate glass structure on results of thermal poling

Two sodium phosphate glasses with different structure (meta- and orthophosphate ones) were thermally poled well below the glass transition temperatures. Glass with an orthophosphate structure (glass LA30) demonstrated a typical behavior of polarization current, that is, monotonic current decrease; however, in glass with a metaphosphate structure (glass LA10) the current first increased for 15–20 min and only then started monotonic decreasing. In spite of the similar sodium content, the current in LA10 glass exceeded the one in LA30 glass by about 10 times. This is explained by the capability of substituting intrinsic sodium ions by more mobile protons entering LA10 glass with a metaphosphate structure from the atmosphere. The other difference consists in the fact that the subanodic layer of LA10 glass after poling has many small cracks, while the subanodic layer of LA30 glass is crystallized. It should be emphasized that the crystallization of phosphate glasses under dc electric field below glass transition temperature is observed for the first time. In addition, after poling, no changes in the refractivity of both glasses were detected, but the generation of the second optical harmonic in LA30 glass was observed.

Effect of Y2O3 Concentration on the Surface and Bulk Crystallization of Multicomponent Silicate Glasses

Multicomponent silicate glasses are crystallized by Y2O3 addition. Depending on the Y2O3 concentration, different crystalline phases evolve. In the absence of Y2O3, a multicomponent glass crystallizes as ZnSnO3, while with the addition of just 3% of this oxide, ZnSnO3 no longer crystallizes and ZrSiO4 appears instead. Different yttrium silicate crystals are formed in all glasses containing Y2O3, but, while α-Y2Si2O7 and β-Y2Si2O7 are favored at low Y2O3 concentrations, the γ-Y2Si2O7 and y-Y2Si2O7 phases are favored at the maximum Y2O3 content. At a 12% Y2O3 concentration, barium and calcium silicate crystalline phases also evolve. Interestingly, the crystalline phases appearing on the surface of the material present different microstructures compared to crystals developed in the bulk. While the crystallized surface presents a tabular-shape type, crystallization in the bulk is of a prismatic type at low Y2O3 concentrations and of a globular (spherical) type at higher concentrations. The main crystal size ranges between 0.85 and 0.75 micrometers, but most of the crystals coalesce to form larger superstructures depending on the Y2O3 concentrations.

Development of 3D Printing Filaments from Recycled PLA Reinforced with Nanoclay

This study focused on the development of 3D printing filaments suitable for fused deposition modeling (FDM) by recycling expired polylactic acid (PLA) filaments. The 3D printing filaments were processed into pellets by incorporating montmorillonite (MMT) nanoclay into the expired PLA filaments through twin-screw extrusion with varying concentrations of 1%, 3%, and 5 wt.%. These composite pellets were reprocessed to filaments through a filament extruder with a diameter of 1.75 mm. These filaments underwent different characterization techniques to test its mechanical and thermal properties. The thermal properties showed increasing values in the glass transition temperature, crystallization temperature, and melting temperature with a decrease in the specific heat upon incorporating increasing amount of MMT nanoclay. Furthermore, thermogravimetric analysis (TGA) showed a positive impact with better thermal stability when the MMT content was incorporated. In terms of mechanical properties, the study showed that the addition of 1 wt% MMT nanoclay, provided an increase in both the tensile strength and elastic modulus comparable to the virgin 3D printing PLA filament.

Insight into the structure and crystallization of SiO2-Al2O3-P2O5-Na2O-MgO-CaO glass system with Mg-Ca substitution: A molecular dynamics study

Transparent glass ceramics (TGCs) have shown great prospects in many application fields. Understanding the effect of oxides on glass network structure and crystallization is essential for designing TGCs. A series of 18Na2O-(16-x)CaO-xMgO-3P2O5-2.5Al2O3-60.5SiO2 (mol%, x = 0, 4, 8, 12, 16) glass-ceramics were studied with Molecular dynamics (MD) simulations, and the effect of CaO substituted by MgO on the glass structure and crystallization was analyzed in details. The results show that MgO statistically behaves as a network former, and the overall network connectivity increases with the substitution of MgO for CaO. Further structure analysis shows that the complex glass system consists of Si-rich and P-rich phases, which respectively contain Si-Mg-rich regions with 2Mg1Si-related tricluster oxygens (TBOs) and P-Mg-rich regions. The energetically unfavorable TBOs and Mg4-O-Mg4 linkages provide favorable nucleation sites for homogeneous nucleation, and the so-called ‘Coordination matching’ principles are proposed to explain the type of crystals. These results help us understand the crystallization of Mg-containing glass ceramics and benefit the future design of novel spontaneous TGCs.

Decoding crystallization behavior of aluminoborosilicate glasses: From structural descriptors to Quantitative Structure – Property Relationship (QSPR) based predictive models

Successful decoding of structural descriptors controlling the crystallization in multicomponent functional glasses can pave the way for the transition from the trial-and-error approach and empirical modeling for glass/glass-ceramic composition design toward more rational and scientifically rigorous Quantitative Structure-Property Relationship (QSPR) based models. However, due to the compositional and structural complexity of multicomponent glasses and the longer time and length scales associated with nucleation, the development and validation of QSPR models are still in it's infancy. The work presented in the article is an attempt to leap forward in this pursuit by combining the strengths of experimental and computational materials science to decode the chemo-structural drivers that promote or suppress nucleation and crystal growth in alkali/alkaline-earth aluminoborosilicate glasses leading to the development of a QSPR-based model (powered by MD simulations). The results reveal the following two descriptors that govern the nucleation and crystallization of a particular aluminosilicate phase in the functional glasses: (1) degree of mixing between the SiO4 and AlO4 units, i.e., Si–O–Al linkages, and (2) difference/similarity between the short-to-intermediate range ordering in the glass structure to that of the structure of corresponding crystalline phase. Based on the established composition–structure–crystallization behavior relationships, a cluster analysis based QSPR model has been developed (and tested) to predict the propensity of nepheline (and anorthite) crystallization in the investigated glasses. The model has been tested on several compositions from the present and previous studies and has successfully predicted the crystallization propensity of all glass compositions, even in cases where previous empirical and semi-empirical models were unsuccessful.

Kinetic analysis of the crystallization of Y2O3 and La2O3 doped Li2O-Al2O3-SiO2 glass.

Li2O-Al2O3-SiO2 (LAS) glass ceramics have a low coefficient of thermal expansion, high mechanical strength, and excellent chemical stability. With advancements in glass ceramics, researchers have explored using LAS glass ceramics with transition metal doping and rare earth doping. Most previous studies have studied the impact of rare earth element doping on crystallization primarily in the context of conventional nucleating agents present in glass. In this study, we aimed to investigate the impact of Y2O3 and La2O3 on LAS glasses in the presence of undoped nucleating agents. The crystallization mechanism of La2O3 and Y2O3 doped LAS glass ceramics was studied using differential scanning calorimetry. The crystallization kinetics of the glasses were analyzed using model-free and modeling methods. Moreover, the activation energy of crystallization and the indices of crystallization and growth of glass ceramics were calculated, and the crystalline phase and microstructure of the samples were characterized. All three fractions of the LAS glass showed consistent crystallization under different calculation methods. The glass doped with La2O3 and Y2O3 exhibited two- or three-dimensional growth during crystallization, promoting crystallization in the LAS glass. The Y3La0 sample demonstrated the most favorable crystallization effect. In the presence of an undoped nucleating agent, rare earth elements can enhance glass crystallization; this new idea can be utilized for the development of new materials.

Bioactive glass–ceramics containing fluorapatite, xonotlite, cuspidine and wollastonite form apatite faster than their corresponding glasses

Crystallisation of bioactive glasses has been claimed to negatively affect the ion release from bioactive glasses. Here, we compare ion release and mineralisation in Tris–HCl buffer solution for a series of glass–ceramics and their parent glasses in the system SiO2–CaO–P2O5–CaF2. Time-resolved X-ray diffraction analysis of glass–ceramic degradation, including quantification of crystal fractions by full pattern refinement, show that the glass–ceramics precipitated apatite faster than the corresponding glasses, in agreement with faster ion release from the glass–ceramics. Imaging by transmission electron microscopy and X-ray nano-computed tomography suggest that this accelerated degradation may be caused by the presence of nano-sized channels along the internal crystal/glassy matrix interfaces. In addition, the presence of crystalline fluorapatite in the glass–ceramics facilitated apatite nucleation and crystallisation during immersion. These results suggest that the popular view of bioactive glass crystallisation being a disadvantage for degradation, apatite formation and, subsequently, bioactivity may depend on the actual system study and, thus, has to be reconsidered.

Magneto-optical and luminescent properties of Tb doped Ge-B-X (X=Ga/La) glasses

Extensive efforts have been devoted to magneto-optical (MO) glass, owing to its remarkable potential in modern optics, encompassing diverse applications such as optical isolation, modulation, and sensing. Although the Tb ions doped glass has good MO properties, high concentrations of Tb ions tend to cluster, resulting in glass crystallization. To further improve the performance of MO glass, we must improve the solubility of Tb ions and inhibit the oxidation of paramagnetic Tb3+ to diamagnetic Tb4+ by adjusting the glass composition. In this work, we conducted a comparative study on GeO2-B2O3-X2O3 glasses doped with Tb2O3 (TGBX, where X represents Ga or La) to elucidate the effects of Ga2O3 and La2O3 on glass properties. Our findings reveal that TGBG glasses exhibit superior MO performance compared to TGBL glasses. Notably, the Verdet constant of TGBG glass with 45 mol.% Tb2O3 at 650 nm reaches 105 rad/(T·m). Although TGBL glass exhibits a lower Verdet constant, its higher glass network connectivity and higher concentration of Tb3+ ions suggest its potential for preparing larger-sized glasses with an increased Tb3+ molar ratio.

Extending the glass formation of alkali tellurites

The physical properties of low alkali content tellurite glasses of composition xM2O.(1−x)TeO2 (0≤x≤0·35) have been previously collected in this laboratory. The twin-roller rapid quenching technique (cooling rate>105°C/s), used within a nitrogen environment, successfully and significantly extended the glass-forming range in the lithium and sodium tellurite systems. The upper range for modification has been extended from x=0·35 to 0·80 and up to x=0·625 for the lithium and sodium systems, respectively. In the K, Rb and Cs tellurites, the glass forming ranges were not increased. Glass transition temperature (Tg), crystallisation temperature (Tx), density, molar volume, packing fraction, ionic conductivity and Raman spectra were obtained for these glasses. These results showed structural changes as a function of composition and carbonate retention in the glasses as the amount of alkali modifier increased above x=0·5.

Evaluation of novel radiation protection devices during radiologically guided interventions

BackgroundIn radiologically guided interventions, medical practitioners are subjected to radiation exposure, which may lead to radiation-induced diseases. In this study, novel radiation shields for the head and neck were evaluated for their potential to reduce radiation exposure.MethodAn anthropomorphic phantom was exposed on its left side to scattered radiation from beneath to simulate the exposure of an operator in a x-ray operating room. Thermoluminescent dosimeters (TLDs) were positioned at different depths in five slices in the phantom, measuring personal dose equivalent. Two different set up situations were evaluated: a head protector designed to reduce radiation in the upper section of the head; and a novel thyroid protector prototype extended in the front and on both sides, designed to reduce radiation in the lower and middle sections of the head. A standard thyroid collar prototype and a ceiling mounted lead glass shield were used as comparisons.Furthermore, the head protector was evaluated in a clinical study in which TLDs were positioned to measure scattered radiation exposure to the heads of operators during endovascular interventions.ResultsThe extended thyroid protector reduced the scattered radiation in the throat, chin, and ear slices. Some shielding effect was seen in the brain and skull slices. The head protector showed a shielding effect in the skull slice up to two cm depth where it covered the phantom head. As expected, the ceiling mounted lead glass shield reduced the scattered radiation in all measuring points.ConclusionsA ceiling mounted lead glass shield is an effective radiation protection for the head, but in clinical practice, optimal positioning of a ceiling mounted lead shield may not always be possible, particularly during complex cases when radiation protection may be most relevant. Added protection using these novel guards may compliment the shielding effect of the ceiling mounted lead shield. The head protector stand-alone did not provide sufficient protection of the head. The extended thyroid protector stand-alone provided sufficient protection in the lower and middle sections of the head and neck.Graphical

Effect of Degradation on the Physicochemical and Mechanical Properties of Extruded Films of Poly(lactic acid) and Chitosan.

This study addresses the fabrication of extruded films using poly(lactic acid) (PLA) and chitosan, with and without maleic anhydride as a compatibilizing agent, for potential applications in disposable food packaging. These films underwent controlled conditions of UV irradiation, water condensation, and temperature variations in an accelerated weathering chamber. The investigation analyzed the effect of different exposure periods on the structural, morphological, mechanical, and thermal properties of the films. It was observed that PLA films exhibited a lower susceptibility to degradation compared to those containing chitosan. Specifically, the pure PLA film showed an increase in elastic modulus and strength during the initial 144 h of exposure, associated with cross-linking induced by UV radiation. On the other hand, film Q2 composed of PLA, chitosan, and maleic anhydride and Q1 without maleic anhydride experienced a tensile strength loss of over 50% after 244 h of exposure. The Q2 film exhibited greater homogeneity, leading to increased resistance to degradation compared to that of Q1. As the degradation time increased, both the Q1 and Q2 films demonstrated a decline in thermal stability. These films also exhibited alterations in crystallinity attributed to the chemo-crystallization process, along with fluctuations in the glass transition temperature and crystallization, particularly at 288 h.

The Substitution of Rare-Earth Gd in BaScCuTe3 Realizing the Band Degeneracy and the Point-Defect Scattering toward Enhanced Thermoelectric Performance.

Zintl compounds have continuously received significant attention, primarily due to their structural characteristics that align with the properties of the electron crystal and phonon glass. In this study, the crystal structure and thermoelectric properties of the quaternary Zintl chalcogenide BaScCuTe3 are investigated. The band structure calculations for BaScCuTe3 reveal a slight energy split of 0.08 eV between the second valence band and the valence band maximum, suggesting the presence of multiband-transport behaviors. Substitution of rare earth Gd for Sc is conducted, which significantly increases the hole concentration from 4.1 × 1019 cm-3 to 8.2 × 1019 cm-3 at room temperature. Meanwhile, the Seebeck coefficient increases because of the participation of the second valence band. A maximum power factor of 6.56 μW/cm·K2 at 773 K is obtained, which is 72% higher than that of the pristine sample. Moreover, the lattice thermal conductivity decreases from 0.57 W/m·K for BaScCuTe3 to 0.48 W/m·K for BaSc0.97Gd0.03CuTe3 at 773 K, owing to the introduction of point-defect scattering. As a result, there is a noteworthy improvement in the thermoelectric figure of merit zT, increasing from 0.44 for the undoped sample to 0.85 for BaSc0.98Gd0.02CuTe3. Considering these findings, BaScCuTe3 exhibits great potential and holds promise for further investigation in the field of thermoelectric materials.

Thermal Effects and Glass Crystallization in Composite Matrices for Immobilization of the Rare-Earth Element–Minor Actinide Fraction of High-Level Radioactive Waste

The current policy of managing high-level waste (HLW) derived in the closed nuclear fuel cycle consists in their vitrification into B-Si or Al-P vitreous forms. These compounds have rather limited capacity with respect to the HLW (5–20 wt%), and their properties change over time due to devitrification of the glasses. Cardinal improvement in the management of HLW can be achieved by their separation onto groups of elements with similar properties, followed by their immobilization in robust waste forms (matrices) and emplacement in deep disposal facilities. One of the possible fractions contains trivalent rare-earth elements (REEs) and minor actinides (MAs = Am and Cm). REEs are the fission products of actinides, which are mainly represented by stable isotopes of elements from La to Gd as well as Y. This group also contains small amounts of short-lived radionuclides with half-lives (T1/2) from 284 days (144Ce) to 90 years (151Sm), including 147Pm (T1/2 = 2.6 years), 154Eu (T1/2 = 8.8 years), and 155Eu (T1/2 = 5 years). However, the main long-term environmental hazard of the REE–MA fraction is associated with Am and Cm, with half-lives from 18 years (244Cm) to 8500 years (245Cm), and their daughter products: 237Np (T1/2 = 2.14 × 106 years), 239Pu (T1/2 = 2.41 × 104 years), 240Pu (T1/2 = 6537 years), and 242Pu (T1/2 = 3.76 × 105 years), which should be immobilized into a durable waste form that prevents their release into the environment. Due to the heat generated by decaying radionuclides, the temperature of matrices with an REE–MA fraction will be increased by hundreds of centigrade above ambient. This process can be utilized by selecting a vitreous waste form that will crystallize to form durable crystalline phases with long-lived radionuclides. We estimated the thermal effects in a potential REE–MA glass composite material based on the size of the block, the content of waste, the time of storage before immobilization and after disposal, and showed that it is possible to select the waste loading, size of blocks, and storage time so that the temperature of the matrix during the first decades will reach 500–700 °C, which corresponds to the optimal range of glass crystallization. As a result, a glass–ceramic composite will be produced that contains monazite ((REE,MA)PO4) in phosphate glasses; britholite (Cax(REE,MA)10-x(SiO4)6O2) or zirconolite ((Ca,REE,MA)(Zr,REE,MA)(Ti,Al,Fe)2O7), in silicate systems. This possibility is confirmed by experimental data on the crystallization of glasses with REEs and actinides (Pu, Am). The prospect for the disposal of glasses with the REE–MA fraction in deep boreholes is briefly considered.

A highly stable and conductive cerium‐doped Li7P3S11 glass‐ceramic electrolyte for solid‐state lithium–sulfur batteries

AbstractIn this report, a facile wet chemical method using acetonitrile combined with thermal annealing was used to prepare Li2S‐P2S5 (LPS) based glass‐ceramic electrolytes with (1 wt%, 3 wt%, and 5 wt% Ce2S3) and without Ce2S3 doping. The crystal structure, ionic conductivity, and chemical stability of Li7P3S11 glass‐ceramic electrolytes were examined at varying temperatures (250–350°C). The results indicated that the highest ionic conductivity of 3.15 × 10−4 S cm−1 for pure Li7P3S11 was observed at a temperature of 325°C. By incorporating 1 wt% Ce2S3 and subjecting it to a heat treatment at 250°C, the glass ceramic electrolyte attained a remarkable ionic conductivity of 7.7 × 10−4 (S cm−1) at 25°C. Furthermore, it exhibited a stable and extensive electrochemical potential range, reaching up to 5 volts when compared to the Li/Li+ reference electrode. By tuning the glass transition and crystallization temperature, cerium doping seems to make Li7P3S11 more chemically stable, compared to its original 70Li2S‐30P2S5 counterpart. According to Raman and X‐ray photoelectron spectroscopy analyses, cerium doping inhibits the decomposition of highly conductive P2S74‐ (pyro‐thiophosphate) to PS43− and P2S64−. Doped LPS has a greater crystallinity and more uniform microstructure than pure LPS, according to XRD, Raman spectroscopy, and scanning electron microscopy analysis. Consequently, Li7P2.9Ce0.1S11 electrolyte shows great potential as a solid‐state electrolyte for constructing high‐performance sulfide‐based all‐solid‐state batteries.

Impact of Shadow Glass Transition on Crystallization in Metallic Glass

Impact of Shadow Glass Transition on Crystallization in Metallic Glass

Study of properties of guar gum and its use in development of packaging film

Discarded plastic materials are now a potential problem throughout the globe; therefore, researchers today attach huge importance and applicability to green chemistry and the sustainable development of biopolymer-based materials that can fulfil the needs of synthetic plastics and polymers and save the biological community of the globe. In this work, a new packaging film was developed by using polyvinyl alcohol (PVA) and guar gum (GG) modified with n-octenyl succinic anhydride (OSA). The objective of the work is to develop a water-resistant film for food packaging applications. In synthesizing the biomaterial film, PVA, glycerol, and guar gum with OSA are used to enhance the capability of water resistance, and the major aim of this study is to improve the hydrophobic nature of guar gum through modification with OSA. The glass transition temperature (Tg = 114.45 °C), crystallization temperature (Tc = 176.85 °C), and melting temperature (Tm = 191.28 °C) of the films indicated better thermal stability. In the characterization study, it was found that 30 % GG/PVA with 5 % OSA provides a better result.