Binary Glass System Research Articles

Erosion mechanism of YAG:Ce3+ phosphor in bismuth borate glasses

The poor thermal stability of current commercial white light emitting diodes (WLED) fabricated using a blue chip, a yellow YAG:Ce3+ phosphor (YAG) and resins, restricts their application in fields where long service time and high power lighting systems are required. Incorporating YAG into glass offers a possible way to resolve the problem by removing the organic resins in LED encapsulation. In the present study, YAG glass-ceramics with bismuth borate glass matrices were prepared using a rapid melt quenching technique. The YAG erosion mechanism was investigated for the first time in various glass matrix compositions at different co-sintering temperatures. The results demonstrate that neither B2O3 nor Bi2O3 individually erodes YAG particles, but the mixtures of B2O3 and Bi2O3 binary glass systems react with YAG and dissolve it almost completely or generate YAl3(BO3)4 (abbreviated as YAB), and they even erode as-produced YAB again under certain conditions. The production of YAB particles increases with the increase of the nBi/nB ratio at a lower temperature (680°C), while it first increases and then decreases at a higher temperature (800°C). The maximum production of YAB can be obtained at the co-sintering temperature of 680°C with an nBi/nB ratio of 55:45 or at 760°C with an nBi/nB ratio of 35:65. The intermediate Bi4B2O9 phase is found during the transformation of YAG into YAB. A simple but efficient approach is proposed to prevent YAG erosion and increase the luminous properties of YAG glass ceramics to a great extent by simply adding Ca2+ into bismuth borate glass matrices. The degree of YAG erosion decreases with increasing Ca2+ concentration until an impurity phase appears when the Ca2+ concentration exceeds 20mol%. The combination of good white light emission and suitable quantum efficiency as well as higher thermal stability makes the as-prepared YAG glass-ceramics equipped with a blue chip a possible alternative to commercial WLED.

Role of MnO in manganese–borate binary glass systems: a study on structure and thermal properties

Structural and thermal properties of \(x\hbox {MnO}-(100-x)\hbox {B}_{2}\hbox {O}_{3}\) (where \(x=40\), 50 and 60 mol%) glass samples have been investigated with the employment of various techniques. Fourier transform infrared spectroscopy results revealed the influence of MnO on glass matrix. Decrease of B–O bond-related band intensities has been observed. MnO addition was found to introduce broken [\(\hbox {BO}_{2}\hbox {O}^{-}\)]\(_{{n}}\) chains. Differential scanning calorimetry (DSC) measurements presented decreasing \(T_{\mathrm{g}}\) that indicates depolymerization of glass matrix in the considered compositional range. Moreover, thermal stability (TS) parameter has been evaluated using the DSC technique. It slightly decreased with MnO content. X-ray photoelectron spectroscopy results provided the evidence for \(\hbox {Mn}^{2+}\) and \(\hbox {Mn}^{3+}\) presence. Multiplet splitting, close to that of MnO, has been observed. It has been concluded that most of the manganese ions existed in the divalent state. Photoluminescence study revealed that manganese ions are tetragonally co-ordinated in a glassy matrix.

Glassy nature and glass-to-crystal transition in the binary metallic glass CuZr

The prediction for the stability of glassy material is a key challenge in physical science. Here, we report a theoretical framework to predict the glass stability based on stochastic surface walking global optimization and reaction pathway sampling. This is demonstrated by revealing for the first time the global potential energy surface (PES) of two systems, CuZr binary metallic glass and nonglassy pure Cu systems, and establishing the lowest energy pathways linking glassy/amorphous structures with crystalline structures. The CuZr system has a significant number of glassy structures on PES that are $\ensuremath{\sim}0.045\phantom{\rule{0.16em}{0ex}}\mathrm{eV}/\mathrm{atom}$ above the crystal structure. Two clear trends are identified from global PES in the glass-to-crystal transition of the CuZr system: (i) the local Zr-Cu coordination (nearest neighbor) increases, and (ii) the local Zr bonding environment becomes homogeneous. This allows us to introduce quantitative structural and energetics conditions to distinguish the glassy structures from the crystalline structures. Because of the local Zr-Cu exchange in the glass-to-crystal transition, a high reaction barrier $(g0.048\phantom{\rule{0.16em}{0ex}}\mathrm{eV}/\mathrm{atom})$ is present to separate the glassy structures and the crystals in CuZr. By contrast, the Cu system, although it does possess amorphous structures that appear at much higher energy $(\ensuremath{\sim}0.075\phantom{\rule{0.16em}{0ex}}\mathrm{eV}/\mathrm{atom})$ with respect to the crystal structure, has very low reaction barriers for the crystallization of amorphous structures, i.e. $l0.011\phantom{\rule{0.16em}{0ex}}\mathrm{eV}/\mathrm{atom}$. The quantitative data on PES now available from global optimization techniques deepens our understanding on the microscopic nature of glassy material and might eventually facilitate the design of stable glassy materials.

Electron paramagnetic resonance of V4+ ions in the xB2O3–(100−x)TeO2 (x=0 to 50 mol%) binary glass system

Electron paramagnetic resonance of V4+ ions in the xB2O3–(100−x)TeO2 (x=0 to 50 mol%) binary glass system

Characterization in vitro studies and antibacterial properties on a sol-gel derived silver incorporated bioglass

The SiO2-CaO, SiO2-CaO-P2O5 and SiO2-CaO-P2O5-Ag2O glass systems were synthesized by the sol-gel technique and characterized with different techniques such as X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), and Environmental Scanning Electron Microscopy (ESEM). In vitro bioactivity tests were performed in Simulated Body Fluid (SBF). The antibacterial action of 65S5Ag (65%SiO2 + 24%CaO + 6%P2O5 + 5% Ag2O) is attributed exclusively to the leaching of Ag+ ions from the glass matrix. The activity of SiO2-CaO-P2O5-Ag2O was compared with that of its binary and ternary counterpart glass system. The concentrations of Ag-bioglass, in the range of 0.05 mg/mL of culture medium, were found to inhibit the growth of these bacteria.

Visible up-conversion and near-infrared luminescence of Er3+/Yb3+ co-doped SbPO4-GeO2 glasses

Recent advances in glass chemistry have led to new multifunctional optical glasses of great technological importance. Glasses containing high amounts of antimony have been studied for use in nonlinear optics, near-infrared transmission, and as hosts for rare-earth ions in photonic devices. This work describes a luminescence study of Er3+ and Er3+/Yb3+ co-doping in a new SbPO4-GeO2 binary glass system. Near-infrared and visible up-conversion emissions were observed in the green and red regions, which are enhanced when the samples are co-doped with Yb3+. Near-infrared emissions have good quantum efficiency and full width half maximum of 61 nm. Visible up-conversion emissions are governed by two photons and described by excited state absorption, energy transfer and cross-relaxation processes.

The Estimation of Oxide Polarizability andBasicity using Electronegativity for B2O3:M2OGlass System (M=Li, Na, K, Rb)

Glass samples of binary glass system [100-(x+10)] B2O3: (x+10) M2O; x take values in the step of 10, were prepared by conventional melt-quench technique. The concept of average oxide ion polarizability ( α0 2-), and optical basicity (Λ) are estimated by using electronegativity; for some binary oxide glasses. The value of the oxide ion polarizability, α0 2- (Reddy) has a good correlation with basicity, Λ(Duffy). The average electronegativity (χ1av) values are smaller than, oxide ion polarizability ( α0 2-), and basicity, Λ(Duffy) determined with increasing mol % of glass modifiers. It has a good correlation between α0 2- (Reddy), and Λ (Duffy). The present research is another trend of the oxide ion polarizability and basicity determined for binary glasses by using different glass modifier.

Influences of Liquid‐Phase Sintering on Structure, Grain Growth, and Dielectric Behavior of PbZr0.52Ti0.48O3 Ceramics

In this work, to formulate piezoceramic systems such as PbZr0.52Ti0.48O3 (PZT) for low‐temperature co‐fired ceramic (LTCC)‐based devices, liquid‐phase sintering approach is demonstrated. ZnO–B2O3 (ZB) binary glass system is used as sintering aid. X‐ray diffraction (XRD) study confirms the formation of morphotropic phase boundary (MPB; tetragonal + rhombohedral) in PZT prepared by hydrothermal route. ZB is found to induce change in tetragonal/rhombohedral ratio in MPB of PZT. 1%ZB in PZT is found to raise the tetragonality from 71% to 92% in MPB region of PZT. ZB addition in PZT has reduced the sintering temperature from 1250 to 825°C for relative density about 91% with sustaining MPB phase. 1% ZB content is optimal percentage to enhance sinterability and relative density. Uniform dispersion of glass in PZT matrix is confirmed by SEM images. ZB content in PZT is found to controlling grain growth during sintering. Highest dielectric constant and lowest dielectric loss with low sintering temperature (825°C) of 1%ZB among all glass added in PZT exhibit technical suitability of 1%ZB + PZT to use as LTCC‐based energy storage devices.

Studying the Effect of ZnO on Physical and Elastic Properties of (ZnO)x(P2O5)1−xGlasses Using Nondestructive Ultrasonic Method

Binary zinc phosphate glass system with composition of (ZnO)x(P2O5)1−x, (x= 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mol%) was successfully prepared using a conventional melt-quenching method. Composition dependence of physical properties and elastic properties in the (ZnO)x(P2O5)1−xwere discussed in association with the effects of adding zinc oxide (ZnO) as a modifier. The addition of ZnO modifier was expected to produce substantial changes on physical properties of the phosphate glasses. An increase in density values of the phosphate glasses was observed. Elastic moduli were studied by measuring ultrasonic longitudinal and shear velocities (VlandVt) of the glasses at room. Longitudinal modulus, shear modulus, bulk modulus, Young’s modulus, Poisson’s ratio, and Debye temperature(θD)were derived from both data of velocities and respective density of all of the samples. Findings from present work showed dependence of density and elastic moduli of each ZnO-P2O5series on glass composition.

Optical and FTIR structural studies of CoO-doped sodium borate, sodium silicate and sodium phosphate glasses and effects of gamma irradiation-a comparative study

Undoped and CoO-doped three binary glass systems, namely sodium borate, sodium silicate and sodium phosphate glasses were prepared by the melt annealing technique. Combined optical and FTIR spectral studies were carried out for the prepared samples before and after being subjected to a gamma dose of 8Mrad (8×104Gy). Optical spectra of the undoped samples before irradiation reveal strong UV absorption varying in depth with the type of glass and such strong UV spectra are related to the presence of unavoidable trace iron impurities within the raw materials used for the preparation of these three basic glasses. CoO-doped (0.25%) glasses show additional visible absorption spectra which are related to the existence of cobalt in the divalent state (Co)2+ ions which are present in two coordination states, namely the octahedral and tetrahedral forms. The broad visible band of Co2+ ions shows in some instances obvious splitting to three component peaks.Gamma irradiation on undoped glasses causes obvious induced UV–visible bands and their extension depends on the type of glass system. Irradiation of CoO-doped glasses causes an obvious increase of absorption within the visible region.Infrared absorption spectra of the undoped three basic glasses reveal IR vibrational bands which are characteristics to the three specific characteristic structural building units within the borate, silicate and phosphate glasses. The introduction of CoO with the doping level causes minor variations of the IR spectra because of the low doping content together with the presence of cobalt ions in structural modifying sites. Gamma irradiation is observed to cause limited changes within the intensities of some bands in the IR spectra which are attributed to changes in bond lengths and/or bond angles of the structural building units by the irradiation process.

039 Anomalies of water and its solutions, and the problem of sudden nucleation in the phenomenology of biopreservation

The formation of crystals during cooling of simple liquids is normally a mild process, as metastability is relieved by a process of nucleation (usually heterogeneous and random) and the growth of a modest number of separate crystals. However, there are cases in which it can be sudden and explosive and if this would be the case for biological tissues being processed for preservation, it would obviously be a very bad thing. Unfortunately, water and its solutions provide one of the examples where this behavior may be encountered. We discuss the background to the sudden nucleation phenomenon observed long ago without proper understanding in concentrated ionic solutions, describe other examples (never published) of an exaggerated form of the same phenomenon when the initial vitrification was carried out under pressure, and explain its relation to the famous anomalies of water. These we will link to observations in related cases like the crystallization of liquid silicon, and the occurrence of nano-droplets of pure silica in many binary silicate glass systems. Finally, we will discuss the possible relevance of some recent observations on benign interactions of biomaterials with certain hydrated ionic liquids5, to a new “cryo-ionic” approach to biopreservation (replace water by gdm. Source of funding: None declared. Conflict of interest: None declared. austenangell@gmail.com

Enhancement of Electric Conductivity in Transparent Glass–Ceramic Nanocomposites of Bi2O3–BaTiO3 Glasses

The frequency and temperature dependent electrical conductivity measurements for heat-treated binary glass system with composition of (100–x)Bi2O3–xBaTiO3 (x = 20, 30, 40 and 50, in mol%) were carried out. The glass was prepared by melt quenching technique and their corresponding glass–ceramic nanocomposites were obtained by suitable heat treatment. Nanostructured behavior and electrical properties of these glasses and their corresponding glass–ceramic nanocomposites were studied. X-ray diffraction (XRD) and differential scanning calorimetry confirmed the amorphous nature of the glasses. Moreover, XRD patterns of the samples indicate nanocrystallites embedded in the glass matrix. The Fourier transform infrared spectroscopy (FT-IR) spectral analysis showed that the band positions of glass system are within the wave number range of BiO6, BiO3 and TiO6 structural units. It is observed that the electrical conductivity is enhanced by 102–103 times in the transparent glass–ceramic nanocomposite phase. With further heat treatment, the conductivity decreased considerably in the stage of glass–ceramic nanocomposite phase as compared with the glassy phase sample. Therefore, partially devitrified phase is more suitable as cathode material in secondary batteries compared to its vitreous or fully crystalline counterpart. The conduction mechanism was confirmed to obey the adiabatic small polaron hopping (SPH). AC conductivity measurements were performed as a function of temperature and frequency, showing a very slow increasing rate at low temperatures and then a fast rate at higher temperatures.

Mass spectrometry study of glasses based on sulfur, phosphorus, and arsenic

The mass spectrometry study of chalcogenide glasses in the P-S binary system and P-As-S ternary system is used to demonstrate that the composition of the gas phase in binary samples is characterized by the conventional spectra of ions, such as PS 2 + , P2S 7 + , P2S 7 + and P4S 10 + . The introduction of As to the binary glass systems first demonstrated the presence of ions AsPS+, AsPS 4 + , AS2 5 + and As2PS5 + in the gas phase of the ternary chalcogenide system, which correspond to the ternary compositions AsPS4 and As2P2S7 in the solid phase.

Reaching the ionic limit in the (1 − X)[Ca0.5–Mg0.5]O–XSiO2 pseudo binary glass system with 0.5 < X < 0.27: Glass formation and structure

Container-less levitation techniques and CO2-laser heating were used to prepare a series of silicate glasses along the compositional join (1−X)(0.5Ca–0.5Mg)O–XSiO2 with X ranging between 0.50 and 0.27; thus reaching compositions beyond the orthosilicate limit (X=0.33). Polarized and depolarized Raman spectra measured at ambient conditions for all these glasses show systematic and smooth band intensity changes with composition. Qi-species analysis of the isotropic Raman spectra shows the presence a) of bridging oxygens in all glasses studied with silica mole fractions down to X=0.33 and b) of free oxygen at all compositions. Beyond the X=0.33 limit, the connectivity between the SiO4 tetrahedra decreases drastically and the corresponding glass structures are characterized by isolated negatively charged “tetrahedral” SiO44− and O2− anions with M2+ (M=Mg, Ca) as counter cations, held together by pure Coulombic (ionic) interactions. The Boson peak appears in the low-frequency range 70–90cm−1 and its polarization characteristics and frequency shifts with glass composition are pointed out and discussed.

Pockels’ coefficients of alumina in aluminosilicate optical fiber

The photoelastic constants of the alumina component in aluminosilicate optical fibers are evaluated and determined to be p11=−0.237±0.020 and p12=−0.027±0.012, thus confirming that the low and negative pij characteristics of bulk alumina are conserved as part of a binary aluminosilicate glass system in optical fiber form. In order to enumerate these values, the strain- and stress-optic coefficients of two fibers (one with an aluminosilicate core and one with a pure silica core) were measured by applying mechanical tension or twist, respectively, to the fibers and measuring changes to an optical system as a function of the mechanical deformation. In the former, the strain-optic coefficient (eOC) is measured directly by recording changes to the free spectral range of a ring fiber laser. In the latter, the stress-optic coefficient (σOC) is found by measuring the change in polarization angle after linearly polarized light propagates through a segment of twisted test fiber. To the best of our knowledge, this is the first such measurement of its type, i.e., the retrieval of the component photoelastic constants, with their signs, of a multicomponent glass. Binary glass compositions wherein the constituents have opposite signs of the photoelastic constant (such as the aluminosilicates) have the potential to give rise to extremely low values of the Brillouin gain coefficient.

Combined DFT, Deconvolution Analysis for Structural Investigation of Copper –doped Lead Borate Glasses

Samples from binary lead borate glass system doped with minor quantities of copper have been prepared by conventional melt-annealing technique. X-ray diffraction (XRD) has been used to prove the amorphous nature of prepared glasses. Structural and optical properties were investigated using FTIR and UV-vis. Spectroscopic investigations were ap- proved using density function theory (DFT) calculations. Deconvolution analysis technique (DAT) combined with DFT technique were employed to interpret both of the theoretical and experimental IR data of this glass system and their agreement. Experimental IR data reveal the presence of both triangular and tetrahedral borate groups besides the sharing of Pb-O units. Direct and indirect optical energy band gaps before and after doping with different percents of copper were calculated to evaluate the role of copper in the glassy matrix. Undoped glass sample is observed to exhibit strong UV absorption due to the combined contributions of absorption of both Pb 2+ ions and trace iron impurities. The presence of both Cu 2+ ions to- gether with the other copper valence state Cu + has been proved by the appearance of extra visible absorption bands.

Thermal Stability and Structure of Tellurite Glass

Oxyfluoride tellurite glass with the composition of TeO2-AlF3-LaF3-ZnO/ZnCl2/ZnF2 was prepared successfully. The thermal stability and structure of TeO2-AlF3-LaF3 system tellurite glass were studied bySubscript text DSC and IR spectra. The results indicated that glass transition temperature of TeO2-AlF3-LaF3-ZnO/ZnCl2/ZnF2 glass was higher than that of (1-x)TeO2-xAlF3 (x=10%, 20%, 30%, 40%, 50%, in mol%) binary glass system slightly. A small number of ZnF2/ZnCl2/ZnO (5mol%) improved glass thermal stability. After adding 5mol% ZnF2/ZnO/ZnCl2 into fluoride tellurite glass respectively, glass transition temperature increased in turn. The introduction of 5mol% different zinc compounds had a little impact on the glass network structure.

NMR studies of oxide-based glasses

Solid-state nuclear magnetic resonance (NMR) spectroscopy offers an array of options for exploring structural order of amorphous materials both over short (≲0.3 nm) and medium (≲1 nm) ranges. We review the advances reported in the literature for characterizing the structures of oxide-based glasses over roughly the past 15 years. Besides describing the current understanding of basic short-range structural aspects of binary and ternary glass systems that typically involve a single glass modifier and one (silicates and phosphates) or two (e.g., aluminosilicates, aluminophosphates and silicophosphates) network formers, we focus on illustrating the progress made for revealing intermediate-range structural order, such as extracting information about connectivities among the basic building blocks in the glass networks and how more extended structural motifs may be identified. By assuming only relatively basic background in solid-state NMR and/or the structure of glasses, we hope this review will appeal to newcomers of either area.

New approach between the Optical Basicity and the Dielectric Constant through the Molar Polarizability for Some Binary Glasses

Problem statement: In the present study, a new correlation between the optical basiciry which describes the electronic charge clouds around the oxide glass and the dielectric constant has been proposed through the molar polarizability of the binary oxide glasses. Approach: Two experimental forms have been suggested relating the optical basicity and the molar electronic polarizability. Hence, the dielectric constant and the optical basicity for some binary glass systems can be deduced. Results: The molar polarizability and the dielectric constant of these glasses exhibit a linear relation as represented with the optical basicity. We have applied the proposed relation on the binary glasses. Conclusion: It was found that a good agreement as the values determined with experimental results determined by previous researchers.

Thermal and microstructural investigations of oxyfluoride lead germanate glasses

AbstractIn this study, thermal behaviour and microstructural characterization of germanium rich GeO2–PbF2 binary glass system were investigated. The studies were conducted for 10, 20 and 30 mol% PbF2 contents. The thermal behaviour of oxyfluoride lead germanate glasses was studied using differential thermal analysis (DTA) at the heating rate of 10 °C/min, in air flow. Effects of different heating rates and PbF2 content were investigated on the glass transition, crystallization and melting temperatures. The structural investigations of as‐cast and annealed samples which are heat‐treated above crystallization peak temperatures were conducted using X‐ray diffractometry (XRD) and scanning electron microscopy (SEM). Utilizing these techniques, α‐GeO2, α‐PbGe4O9, γ‐PbGe4O9, PbGeO3 and Pb3GeO5 phases were identified. (© 2011 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)