Glass Matrix Research Articles

Designing Advanced Amorphous/Nanocrystalline Alloys by Controlling the Energy State.

Amorphous alloys, also known as metallic glasses, exhibit many advanced mechanical, physical, and chemical properties. Owing to the nonequilibrium nature, their energy states can vary over a wide range. However, the energy relaxation kinetics are very complex and composed of various types that are coupled with each other. This makes it challenging to control the energy state precisely and to study the energy-properties relationship. This brief review introduces the recent progresses on studying the enthalpy relaxation kinetics during isothermal annealing, for example, the observation of two-step relaxation phenomenon, the detection of relaxation unit (relaxun), the key role of large activation entropy in triggering memory effect, the influence of glass energy state on nanocrystallization. Based on the above knowledge, a new strategy is proposed to design a series of amorphous alloys and their composites consisting of nanocrystals and glass matrix with superior functional properties by precisely controlling the nonequilibrium energy states. As the typical examples, Fe-based amorphous alloys with both advanced soft magnetism and good plasticity, Gd-based amorphous/nanocrystalline composites with large magnetocaloric effect, and Fe-based amorphous alloys with high catalytic performance are specifically described.

Fabrication of energy efficient P-i-G structure with novel dysprosium-doped yttrium calcium borate (Dy: Y2CaB10O19) phosphors: Highly efficient materials for cool white light emission conducive to green technology

Novel polycrystalline phosphor-yttrium calcium borate doped with dysprosium ions (Dy3+: Y2CaB10O19) was synthesized for the first time by solid-state reaction technique. The crystal structure was found to be monoclinic having C2 space group. SEM was performed to analyze the surface morphology of the phosphor materials and to assess the distribution of phosphor particles in the glass matrix. Fourier transform infrared (FTIR) spectroscopy of the samples was studied to know the molecules present. The emission spectra by 350 nm excitation possessed characteristic peaks at 480 nm (blue) and 577 nm (yellow). The CIE chromaticity co-ordinate and correlated color temperature (CCT) were deduced to be (x = 0.3384, y = 0.3823) and 5297 K respectively. Luminescence decay time for the optimized phosphor was determined to be 0.70 ms. The prepared phosphors were embedded in the glass matrix at an elevated temperature of 1000 °C. The transmittance spectra of the prepared glass materials were recorded to analyze its transparency in the visible region. The internal quantum yield was deduced to be 53.91 %.

Exploring the effect of Er2O3 content on the structural, thermal, and physical characteristics of zinc silicate glasses

Glasses of chemical formula xEr2O3. (55-x) ZnO. 45SiO2 (x = 0, 0.5, 1, 3, 5, 7, 10, and 15 mol. %) were prepared using the melt-quenching route. The structure of the glasses was investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman, and NMR spectroscopy. XRD data confirmed that all zinc silicate glasses containing Er2O3 had an amorphous glassy structure. XRD showed the presence of two humps around 50° and 60° that are related to Er and Zn ions incorporated into the glass structure, and these humps' intensity changed with Er2O3 addition. The fraction of different silicate structural units is studied using FTIR and Raman spectroscopy, which is comparable to that obtained from the reported NMR values. FTIR, Raman, and NMR measurements confirmed the dual role of Er2O3 on the structure of zinc silicate glasses. Based on these results, Er2O3 content is below 5 mol. % entered as a glass modifier, creating more non-bridging oxygen atoms (NBO, increases Q1) while above 5 mol. % played a glass former, creating more bridging oxygen atoms (BO, increases Q2). Thermal heat treatment was applied for all glass samples according to DSC measurements. The thermal parameters have been discussed and correlated with the glass structure. The glass transition temperature (Tg) escalated from 377.3 at 5 mol. % to 391.04 °C at 15 mol. % Er2O3. The crystallization temperature (Tc) also increased from 548.27 °C to 598.37 °C, and the Vickers hardness (Hv) improved markedly from 646.4 kg/mm2 at 0 mol. % to 732.2 kg/mm2 at 15 mol. % Er2O3. XRD and FTIR results for glass samples after heat treatment for 24 h at 700 °C have been discussed regarding the crystallization of the glass matrix. These findings highlight the critical role of Er2O3 in modifying glass structure and properties, demonstrating its potential to enhance the glass matrix's durability and mechanical strength.

Investigation of structural, physical and optical properties of sodium boro-tellurite glasses doped with iron oxide

In this work, we demonstrate systematic studies on the influence of Fe2O3 on the structural and optical properties of transparent B2O3–TeO2–Na2O glasses containing the different concentrations of Fe2O3. The glasses were prepared via the standard melt quenching method, and the prepared glasses were characterized using, XRD, electron paramagnetic resonance (EPR), FTIR, and UV–visible spectroscopic techniques. Furthermore, we evaluated several physical properties of the glasses, including densities, molar volume, boron-boron separation, and oxygen packing density, with respect to the concentration of Fe2O3 in the host glass matrix. It is observed that the density of the glasses and the average boron-boron distance found increase with Fe2O3 concentration due to the modification in the glass network induced by the dopant ions. EPR spectra reveals the presence resonance signals at g ∼2.04 and g ∼4.26, hence it proves the existence of Fe3+ in distorted octahedral coordination and supported by UV–Vis absorption bands. The FTIR spectra revealed an increase in spectral intensity with the concentration of Fe2O3. This was attributed to the formation of non-bridging oxygens through converting BO4 units into BO3 units, which Fe2O3 mediated. The UV–visible spectral analysis showed a decreased energy band gap from 2.26 to 1.51 eV with increased Fe2O3 concentration. Additionally, we determined the Urbach energy, refractive index, optical basicity, and electronegativity, which are presented in detail.

Unveiling dual crystallization peaks in Zn2P2O7 glass: Insights into stability, nucleation, and growth kinetics

This study reports on the successful synthesis of Zn2P2O7 glass using the conventional melt-quenching method. The state of the material has been investigated using X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC), to verify its amorphous and glassy state with the onset of two distinct crystallization peaks. These peaks were indicative of the transition to α-Zn2P2O7 and γ-Zn2P2O7 phases during the annealing process, a finding that was supported by Fourier-transform infrared spectroscopy (FTIR) analysis. This marked the inaugural occasion where the stabilization of both Zn2P2O7 phases from their respective annealed glassy state was achieved. The crystallization kinetics and associated parameters of Zn2P2O7 glass were deeply delved into, with various models including Kissinger, Ozawa, and the Matusita-Sakka approach. The applied models elucidate the mechanisms of growth and nucleation within the glass matrix. This kinetic study provided valuable insights into the crystallization process, revealing that α-Zn2P2O7 is both kinetically and thermally more stable than the γ-phase. However, it is less thermodynamically stable compared to the γ-phase. Besides, the study of phase transformations and crystallization kinetics was enhanced by the analysis of the Avrami index.

Changes in the magmatic plumbing system associated with the Gotemba sector collapse at Mount Fuji, Japan

It is well known that magmatic plumbing systems change over time, but there is much debate as to why and how. We studied volcanic ejecta continuously deposited in an outcrop at Kagosaka Pass at the eastern base of Mount Fuji to investigate the factors responsible for changes in the magmatic plumbing system. The sample consisted of pyroclastic sediments from explosive eruptions for approximately 3000 y, which sandwiched the time of the Gotemba sector collapse at approximately 2500 BP. Chemical analyses of whole rocks, minerals, and matrix glasses, as well as mode measurements of glass and bubbles, were performed on samples collected from approximately 30 layers; significant changes were observed before and after the collapse. For example, before and after the collapse, matrix glass area increased around 60% to over 80% and anorthite content (Ca / (Ca + Na) * 100) of phenocryst plagioclase decreased from over 80 to below 65. For a period after the collapse, possibly hundreds of years, the plagioclase and olivine phenocrysts exhibited characteristics indicative of crystallization at low temperatures and pressures, and the pyroclast matrix became highly vitreous. Eruptions with ejecta of these characteristics continued more than a dozen times, lasting about 500 years. In addition, the trend in the distribution of the bulk rock chemical composition changed significantly, showing a differentiation trend with only plagioclase and clinopyroxene crystal separation. An investigation using the MELTS software revealed that the phenomenon of direct eruptions from deep magma chambers to the surface, bypassing shallow magma reservoirs, continued for several hundred years after the collapse. This can be interpreted as a decrease in confining pressure associated with the collapse, facilitating the eruption of magma from the depths. Furthermore, based on an examination of the water content in the magma during this period, we posit that the trigger for the rise of magma from the deep magma chamber of Mount Fuji is the acquisition of excess pressure by the injection of magma from a deeper level.

Mechanical Alloying and Concentration Quenching of the Luminescence of Pr3+ Ions in Chalcogenide Glass

The disadvantage of chalcogenide glasses containing rare earth ions as luminescent materials for the IR optical range is the strong concentration quenching of luminescence due to the non-uniform distribution of rare earth ions in the glass matrix. This study investigates the effect of grinding chalcogenide glass containing Pr3+ ions in a planetary ball mill on its luminescent properties in the near-IR range, as well as its optical properties and structure. The results indicate that milling, under certain conditions, leads to a decrease in the concentration quenching of the luminescence of Pr3+ ions. This finding suggests that milling can be used in the development of glassy materials with the increased efficiency of luminescence of rare earth ions. However, it is essential to consider that high-energy milling may result in the formation of areas with increased pressure in the obtained material, leading to structural changes in the glass.

The effect of zinc substitution on the optical properties of Sm3+ doped zinc borate glasses

Zinc borate glasses are a relatively well known glass type that can be produced at comparably low temperatures. Variations in both the type and concentration of network modifier atoms induce structural alterations within the glass matrix. If doped with optically active dopants, e.g. rare earth ions, compositional changes also affect the local surrounding of the dopants and consequently their optical properties such as emission peak shape and peak ratio. To investigate the effect of different low field strength network modifier ions in zinc borate glasses two glass series were prepared using the melt quench technique; Sm3+ was used as dopant ion: 50B2O3, xK2O, (49-x)ZnO, 1Sm2O3 (x = 5,10,15, …, 30 mol%) and 50B2O3, 30MO, 19ZnO, 1Sm2O3 (M = Ca, Sr and Ba). It is found that the substitution of ZnO for K2O notably enhances the intensity of the red Sm3+emission. Based on the literature this effect is attributed to a change in symmetry at the rare earth position. Additionally, the effect of network modifier concentrations and the different network modifier types on the Sm3+ absorption spectra is examined, discussed and compared to literature data. Furthermore, the glasses are characterized according to their density, refractive index, molar volume, and oxygen packing density.

Correlation between structural and optical characterizations of IR transparent sodium modified zinc phosphate oxide glasses

A series of Sodium-modified zinc phosphate glasses was prepared through conventional melt-quenching technique, encompassing compositions xNa2O.20ZnO.(80-x)P2O5, where x varies from 10 to 50. The study delves into investigation of physical, structural, and optical properties of synthesized glass matrix. IR and Raman spectroscopy investigation suggest loosening of the glass network. The depolymerization of glass network results in shorter chains and a transition from higher to lower connectivity states (P3 → P2 → P1 → P0) where the symbols Pn (n represents number of BOs per unit) can be used to classify the structural groups of phosphates. The transparency within both the visible and infrared spectra of the examined glass series demonstrates remarkable levels, ranging from 92 to 96 percent. Additionally, UV-Vis spectra were analyzed using the Mott and Davis Model along with the modified Urbach Energy Model.

Evaluating the residual stresses and fracture behavior of glass-ceramics by numerical modeling

Residual stresses often arise after glass crystallization due to the residual glass and crystal phases' thermal and elastic properties mismatch. Using the Positional Finite Element Method, we developed a computational tool for nonlinear 2D geometric analysis to simulate residual stresses from crystal growth in a glass matrix. We implemented a damage model in which interface elements are introduced into the mesh. These elements' elastic modules were penalized after reaching a tensile stress limit to simulate crack propagation. The crystal mesh was generated separately and included in the glass mesh via kinematic compatibility without introducing degrees of freedom nor requiring mesh conformity. Results were consistent with analytical calculations using Selsing's model. The fracture mode in crystal-glass composite microstructures with different signs of thermal expansion mismatch is closely in accordance with the microstructure pictures in the literature. The adapted damage model showed excellent potential in evaluating and predicting crack patterns due to residual stresses in glass-ceramics.

Effect of B2O3 content on the structural and optical properties of (Ba0.85Ca0.15) (Ti0.9Zr0.1)O3 glass

This study explores the structural and optical properties of (Ba0.85Ca0.15) (Ti0.9Zr0.1)O3 system mixed with B2O3. The samples with the composition xB2O3 + (100-x) (Ba0.85Ca0.15) (Ti0.9Zr0.1)O3 (where x = 5, 10, 20, 30 and 40 mol. %) were prepared using the melting quenching technique to form borate-based glass containing BaO, CaO, ZrO2 and TiO2 (BBCZT). X-ray diffraction analysis confirmed the amorphous nature of the prepared samples. The macroscopic structure of the glasses was assessed from the density measurements determined through Archimedes' principle, while information regarding the atomic structural units and vibrational modes were obtained from Infrared measurements. Increasing the B2O3 content led to variation of the relative intensity of these modes together with a decrease (increase) in density (molar volume), indicating a less dense and open-structure for the glass network. The absorption spectra showed absorption bands associated with the optical transitions B22g→B21g and B22g→A21g of Ti3+ ions occupying distortion octahedral sites (TiOh3+) in the glass matrix. The ligand field strength (10Dq), optical energy gap (Eopt), Urbach's energy (ΔE), and nonlinear optical properties (NLO) were calculated in the study.

Deformation-Induced Crystal Growth or Redissolution, and Crystal-Induced Strengthening or Ductilization in Metallic Glasses Containing Nanocrystals.

It is generally known that the incorporation of crystals in the glass matrix can enhance the ductility of metallic glasses (MGs), at the expense of reduced strength, and that the deformation of MGs, particularly during shear banding, can induce crystal formation/growth. Here, we show that these known trends for the interplay between crystals and deformation of MGs may hold true or become inverted depending on the size of the crystals relative to the shear bands. We performed molecular dynamics simulations of tensile tests on nanocrystal-bearing MGs. When the crystals are relatively small, they bolster the strength rather than the ductility of MGs, and the crystals within a shear band undergo redissolution as the shear band propagates. In contrast, larger crystals tend to enhance ductility at the cost of strength, and the crystal volume fraction increases during deformation. These insights offer a more comprehensive understanding of the intricate relationship between deformation and crystals/crystallization in MGs, useful for fine-tuning the structure and mechanical properties of both MGs and MG-crystal composites.

Characterization of Z cluster connectivity in CuZr metallic glasses.

Previous studies have proposed that the backbone of metallic glasses consists mainly of high-centrosymmetric structures, particularly Z clusters, which are responsible for the strength of the glass matrix. However, exploring these networks involves medium-range order analysis, a topic still not fully understood in the literature. This study investigates the atomic connectivity of CuZr metallic glasses by analyzing Z clusters using complex networks to establish their relationship with the mechanical behavior. Our results reveal higher connectivity and larger network sizes in the sample exhibiting the most pronounced stress overshoot, while the opposite trend is observed in samples with less pronounced stress overshoot. Metrics, such as density and clustering coefficient, further validate the correlation between Z cluster connectivity and mechanical behavior. These findings underscore the critical role of Z cluster connectivity in understanding the mechanical response of metallic glasses. Molecular dynamics simulations were conducted using the LAMMPS software. Atomic interactions in Cu Zr metallic glasses were modeled using the embedded atom method, and compression tests were performed to assess the mechanical response. Atomic connectivity was examined through complex network analysis based on Z clusters, utilizing the NetworkX library for the Python programming language. Within this framework, parameters such as the average coordination number, network size, and network density were calculated, revealing the relationship between the interpenetrating Z cluster structure and the mechanical response of the samples.

Novel cesium immobilization by alkali activation and cold consolidation of waste pharmaceutical glass

A new method of cesium immobilization has been successfully developed by combining alkali activation of boro-alumino-silicate glass and viscous flow sintering. Powdered glass from discarded pharmaceutical vials, suspended in a 2.5 M CsOH aqueous solution, underwent surface hydration as well as partial dissolution. Condensation reactions occurring at hydrated surface layers upon drying at 40 °C over 7 days resulted in welding of adjacent particles, forming a network that trapped newly formed gel and crystal phases. The newly formed phases including crystalline boro-pollucite (CsBSi2O6), were derived mostly from Cs+ ions reacting with the products of glass dissolution and exhibited a high chemical stability. Further stabilization was achieved through viscous flow sintering at 700 °C, resulting in the incorporation of Cs+ ions in a glass matrix. The effectiveness of the immobilization was confirmed by leaching test using the Materials Characterization Center-1 Standard (MCC-1). This innovative approach not only enhances the chemical stability of cesium waste forms, but also aligns with principles of cleaner production by repurposing pharmaceutical glass waste, promoting sustainable materials management.

Effect of striae on the high temperature dielectric and electrical properties of lithium aluminosilicate glass-ceramics

Lithium Aluminosilicate glass-ceramics with striae (LAS-WS) and without striae (LAS-WoS) were processed using melt casting technique. LAS-WS and LAS-WoS samples were characterized and found stress birefringence >10 nm/cm and <10 nm/cm, respectively. LAS-WS and LAS-WoS samples were subjected to structural, microstructural, high temperature dielectric and electrical characterization. The presence of striation did not significantly affected the formation of β-spondumene structure during crystallization heat treatment. TEM image confirms the formation of nanocrystals in the glass matrix of lithium aluminosilicate glass-ceramics. The homogeneous distribution of LAS nanocrystals of average size of 3–6 nm is evident from TEM results. Stress birefringence distribution in lithium aluminosilicate glass-ceramic clearly shows the striae formation. Shadowgraphy images confirmed the striae free and striae containing regions in the glass-ceramic. The effect of striae on dielectric properties and AC conductivity was analysed using impedance spectroscopy and it was found that the value of the relative permittivity decreased from 415 (1.2 Hz) to 9.76 (1.2 MHz) for LAS-WoS and from 401 (1.2 Hz) to 10.3 (1.2 MHz) for LAS-WS, respectively. It was found that striae in LAS glass-ceramics influence the electrical impedance and AC conductivity relaxation process rather than relative permittivity. The effect of striae on crystallization and morphology are presented. Both the samples have shown crystallinity of more than 75 %. The electrical conductivity of σ = 2.0 × 10−3 S/cm for LAS-WoS and 2.7 × 10−3 S/cm for LAS-WS at 300 °C as well as σ = 4.6 × 10−3 S/cm for LAS-WoS and 6.9 × 10−3 S/cm for LAS-WS at 700 °C are found to be in good agreement due to increase in the electrical conductivity with temperature. The ionic conductivity of the material due to Li-ion mobility with respect to temperature and electric field and possible mechanism of AC conductivity are discussed. The results presented indicates the potential application of this material that demands high temperature operation of lithium aluminosilicate glass-ceramics.

Nanomechanical properties of ceramic materials from the SiO2–Al2O3-(Na2O)–K2O–MgO system with an addition of SrO

The ceramic materials studied in this paper consist of finely dispersed crystalline phases embedded in a glassy matrix, which is similar to glass-ceramic materials, porcelain, and VC products. The strength depends then not only on the properties of the individual crystalline phases but also on their interactions and the matrix. Differences in mechanical properties for materials with similar chemical compositions are most likely related to diverging microstructures. Crystal orientation, grain-size distribution and shape, the ratio of the glass matrix to the crystalline phase, and homogeneity control the flexural strength of glass-ceramic materials. The subject of the study is whiteware ceramic materials from the SiO2–Al2O3–Na2O–K2O–MgO–SrO system, fired similarly to the regime used for VC products. The effect of the type of alkali oxide and the share of SrO were tested. This paper presents the results of hot-stage microscopy, X-ray diffraction (XRD), scanning electron microscopy with a micro-analyzer (SEM-EDS) and biaxial flexural strength measurements. Additionally, nanoindentation technique was used to access local mechanical properties.

Transparent SrAl2O4:Eu2+, Dy3+ glass-ceramics with significant mechanoluminescence

Transparent SrAl2O4:Eu2+,Dy3+ glass-ceramics with significant mechanoluminescence (ML) have been prepared by the melt quenching method. Phase composition and crystal morphology of the glass-ceramics have been studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests indicate that SrAl2O4 crystals in the glass matrix have an oriented growth characteristic influenced by the doping Dy3+ ions. Meanwhile, more Dy3+ ions doping results in refined grain structures and a more ordered arrangement of crystals. Photoluminescence (PL) spectra show that as the concentration of Dy3+ ions increases, the luminescence intensity of the glass-ceramics decreases, but long persistent luminescence (LPL) enhances. The emission peaks at 522 nm attributed to 4 f65d1→4 f7 transitions, arise from the combined luminescence effect of Eu2+ ions in both crystal and glass phases. Further investigation indicates that the as-prepared glass-ceramics exhibit significant mechanoluminescence (ML), which can last for a relatively long duration.

Improving Extended L-Band Fiber Amplifiers Using Er3+: Y3+ Co-Doped Silicate With Optimized Alumino-Phospho-Silicate Glass Matrix

Improving Extended L-Band Fiber Amplifiers Using Er³⁺: Y³⁺ Co-Doped Silicate With Optimized Alumino-Phospho-Silicate Glass Matrix

Radial IR-GRIN lens prepared by multi-temperature fields manipulated gradient crystallization within chalcogenide glass

Chalcogenide glass has achieved great success in manufacturing axial-type infrared gradient refractive index (IR-GRIN) lenses. However, studies on radial-type IR-GRIN lenses, which are more ideal for optical design, remain rare. The present study introduces what we believe to be a new method for preparing radial IR-GRIN lens by creating high refractive index (n) In2S3 nanocrystals within a 65GeS2-25In2S3-10CsCl (GIC, in molar percentage) glass matrix. Upon introduction of multi-temperature field manipulation, we have successfully achieved central crystallization and simultaneous gradient attenuation spreading toward the edge within GIC glass, providing a radial GRIN profile with Δn over 0.1 while maintaining excellent IR transparency. In addition, the optical and structural properties of the GIC GRIN samples were characterized. The relationship between Raman intensity and the n of glass ceramics at different heat treatment temperatures was investigated, thereby enabling the indirect confirmation of the presence of radial gradient crystallization within the prepared GIC GRIN samples through Raman intensity. Multiple experimental results have shown that this approach has excellent reproducibility and potential for large-scale productions.

Enhanced UVB 311 emission in Sb2O3–SiO2 glasses doped with Gd2O3 and tailored Pb3O4 content for potential phototherapy

This study investigates the enhancement of the sharp 311 nm UVB emission from Gd3+ ions in antimony silicate glass system doped with a fixed concentration of Gd2O3 (1.0 mol%) and varying amounts of red lead (40–10 mol%). The emission spectra revealed an intense sharp UVB band at 311 nm, originating from the 6P7/2 → 8S7/2 transition of gadolinium ions upon excitation at 273 nm. Interestingly, the intensity of this band nearly doubles as the Pb3O4 content decreases from 40 to 10 mol%. Such improvement was attributed to the decomposition of Pb3O4 into various phases that include α-PbO2, β-PbO2 polymorphs, and PbO. Out of these decomposition products, PbO acted as modifiers, reduced phonon losses and consequently enhanced the emission intensity. The decrease in Pb3O4 content is also hypothesized to promote de-clustering of Gd3+ ions within the glass matrix. This de-clustering reduced cross-relaxation losses, further contributed to the observed emission enhancement. In summary, this study demonstrated a successful strategy for boosting the UVB emission from Gd3+ ions in antimony silicate glasses by manipulating the content of Pb3O4.