B2O3 SiO2 Research Articles

Luminescence and scintillation properties of CuO-doped SiO2–B2O3–La2O3 glass

A CuO-doped SiO2–B2O3–La2O3 glass system was prepared through high-temperature melting and the Si powders were used as reducing agent to reduce Cu2+ to Cu+. The spectral properties, electron paramagnetic resonance spectra, and scintillation luminescence under X-ray irradiation were measured. The Cu+ ions in the borosilicate glasses exhibited both luminescent centers under ultraviolet light excitation, which are isolated Cu+ ions and Cu+–Cu+ ion pairs, respectively. There is an energy transfer process from isolated Cu+ ions to Cu+-Cu+ ion pairs, which strongly affects radioluminescence. The luminescent intensity of the Cu+–Cu+ ion pairs became increasingly apparent with the increase in CuO doping concentration, and the optimum concentration was 0.4 mol% for the photoluminescence and radioluminescence.

Crystallization kinetics, structure and dielectric properties of CaO–B2O3–SiO2 glass–ceramics nucleated by composite nucleating agents

The crystallization kinetics, structure and dielectric properties of CaO-B2O3–SiO2 (CBS) glass–ceramics, nucleated by composite nucleating agents (TiO2, ZrO2), are systematically investigated. The results reveal that the addition of composite nucleating agent (TiO2/ZrO2) destroyed the continuity of the glass network structure formed by SiO2 and B2O3, promoted the precipitation of wollastonite phase and enhanced the dielectric properties of as-prepared CBS glass–ceramics. However, the composite nucleating agent increased the crystallization temperature of the glass and introduced some impurity phases, influencing the microscopic arrangement of the wollastonite phase, whereas the content of impurity phases decreased with the increase of TiO2 content in the composite nucleating agent. Furthermore, the crystallization kinetics study showed that the composite nucleating agent reduced the crystallization activation energy of glass, and the crystallization of glass is controlled by one-dimensional interfacial crystal growth.

Fluorescence features of Tm3+-doped multicomponent borosilicate and borotellurite glasses for blue laser and S-band optical amplifier applications

Novel B2O3–SiO2–Al2O3–ZnO–Li2O/MgO and B2O3–TeO2–PbO–ZnO–Li2O–Na2O glasses with different concentrations of Tm2O3 were synthesized by using the melt-quench method. All the fabricated samples have been characterized by visible emission spectra and decay times, including near-infrared (NIR) luminescence measurements. For 0.5 mol% Tm3+-doped borotellurite glass, several radiative parameters are evaluated using the Judd-Ofelt parameters. The intensity of all the visible emission bands increased with the increase of Tm2O3 concentration up to 0.5 mol%, and beyond this doping content, luminescence concentration quenching takes place. The luminescence intensity quenching is attributed to energy transfer (ET) processes through cross-relaxation (CR) channels. The visible luminescence decay curves were well fit with a single exponential (for Tm3+: 1D2 level) and double exponential (for Tm3+: 1G4 level) functions for the multicomponent borosilicate samples, while Inokuti-Hirayama model was used for the multicomponent borotellurite glass 1D2 level decay time fit. The derived decay lifetimes of the 1D2 level are found to be much shorter than that of the 1G4 level. In Li2O (alkali) or MgO (alkaline) containing borosilicate samples, pumped under 808 nm laser diode, the 3H4→3F4 (1.458 μm) emission intensity increased from 0.1 to 2.0 mol% Tm3+ ion concentration, indicating negligible CR processes. The computed Full-Width at Half-Maximum (FWHM) values for the 1458 nm emission in 2.0 mol% Tm3+-doped Li and Mg series borosilicate samples are 117 and 125 nm, respectively, while the FWHM value for 0.5 mol% Tm2O3 content doped borotellurite glass is 118 nm. Following the analyzed visible and NIR optical results, the fabricated Tm3+ glasses could be useful for blue laser and S-band optical amplifier applications.

Optical properties and zero photoelastic constant of ns2-type metal cation containing oxide glasses

Zero photoelasticity and the relevant optical properties in binary RO–SiO2 (R = Sn, Pb) and R′2O3–SiO2 (R′ = Sb, Bi) and ternary Bi2O3–B2O3–SiO2 glasses were systematically studied. The zero photoelastic silicate glass leads to zero stress-induced birefringence, providing application to an optical lens, a filter, a beam splitter, and a fiber optic sensor without stress-induced birefringence. In this study, a variety of zero photoelastic binary silicate and ternary borosilicate glasses with optical bandgaps of 3.1–3.9 eV containing highly polarized ns2-type cations are reported.

Structure, crystallization, and dielectric properties of the Al2O3 filled CaO–B2O3–SiO2–Al2O3 glass composites for LTCC applications

The glass structures and crystallization behaviors of CaO–B2O3–SiO2 (C1) and CaO–B2O3–SiO2–Al2O3 (C1A03) glasses are investigated. The addition of Al3+ into CaO–B2O3–SiO2 glass acts as a glass former and bonds with the silicon tetrahedron with non-bridged oxygen to form Si–O–Al–O–Si, which increases the Q4 structural unit. The relative dielectric constants for C1 and C1A03 glass systems were all about 7.8–8.4. Compared to the C1 glass, the size and amount of pores decreased for the C1A03, leading to a higher dielectric constant. The C1A03 glass system exhibits better Qxf value than the C1 system due to the decrease in the size and amount of pores. The Qxf value roughly decreased with increasing glass addition for the densified samples. The C1A03 glasses with 50 wt% alumina exhibited the highest dielectric constant (8.4) and Qxf value (3150 GHz) due the maximum densification and highest amount of anorthite were obtained.

Improvement of gold electrode conductivity after cofiring with CaO–B2O3–SiO2 green tapes for LTCC application

The cofiring process of Au paste containing various amount of glass additive with different properties and CaO–B2O3–SiO2 (CBS) green tapes was investigated. The initial shrinkage temperature of Au paste was strongly associated with the softening point and the content of glass additive. The swell of sample and its mechanism during cofiring process was reported. The sheet resistivity of Au electrode was greatly depended on the content of CBS glass additive. When the content of CBS glass additive with the softening point of 704 °C was 3 wt %, the Au electrode exhibited the highest conductivity with the sheet resistivity of 2.4 mΩ/sq. The results obtained in this paper revealed the relationship between the glass additive and cofiring defects of Au electrode in the metal/ceramic multilayer structure, which gave an avenue to manufacture Low temperature co-fired ceramics (LTCC) modules with good quality.

Microstructure evolution and cooperative reinforcement mechanisms of Al2O3/Al2O3 joints brazed by low-melting borosilicate glass

The Al2O3/SiO2–B2O3–Al2O3–Na2O glass/Al2O3 joints reinforced cooperatively by glass matrix and in-situ Al4B2O9 whiskers were obtained via a low-melting borosilicate glass braze. The composition of glass seam transformed from SiO2–B2O3–Na2O to SiO2–B2O3–Al2O3–Na2O due to continuous diffusion and dissolution of Al2O3. An appropriate amount of [AlO4] units introduced into the glass braze played a vital role in strengthening the glass network structure resulting to considerably improved mechanical strength of the glass seam. Meanwhile, plenty of in-situ Al4B2O9 whiskers growing from the Al2O3/glass braze interface to the center of glass seam in various directions generated. Three-dimensional crisscross structures were fabricated at the Al2O3/glass braze interface domains, where were enhanced by crack-bridging and pull-out effect of the whiskers. Generally, ascribed to the cooperative reinforcement of the glass matrix in the seam and in-situ Al4B2O9 whiskers at Al2O3/glass braze interface domains through reactions of Al2O3 and borosilicate glass braze, strength of the as-brazed joints was promoted prominently. The shear strength of the joints reached a maximum of 61 MPa brazed at 1050 °C for 60 min.

The viscosity of Bi2O3–B2O3–SiO2 glasses and melts

The viscosity of Bi2O3–B2O3–SiO2 glasses and melts

Preliminary biological evaluation of tantalum containing soda lime borosilicate bioactive glasses

The importance of the current investigation was to understand the in vitro studies of tantalum (Ta) containing amorphous glass system, i.e., B2O3–SiO2–CaO–Na2O–Ta2O5 (TaBG). The bioactivity and cytocompatibility studies of the glass system was performed with physiological fluid i.e., simulated body fluid and MTT assay respectively. The glass system B2O3–SiO2–CaO–Na2O–Ta2O5 was prepared by conventional melting and annealing technique and characterized for in-vitro biological and mechanical properties. Bioactivity study was performed with simulated body fluid, by immersing amorphous powder samples up to twenty-one days. Different techniques like structural (XRD), functional (FTIR), morphological (SEM) and elemental (EDS) analytical methods were performed to assess the apatite-forming ability i.e., bioactivity. Cytocompatibility has been performed by the ISO 10993–5. Microhardness has been measured with indentation method. Bioactivity of the tantalum doped glasses was affected by the incorporation of tantalum content. Microhardness significantly improved and cell viability was not affected for the glass system by the addition tantalum. Hence, the findings in the present study were encouraging to be used as bone implant for appropriate medical applications.

Effects of Li2O–B2O3–SiO2–CaO–Al2O3 glass addition on the sintering behavior and microwave dielectric properties of Li3Mg2NbO6 ceramics

Li3Mg2NbO6 ceramics modified with Li2O–B2O3–SiO2–CaO–Al2O3 (LBSCA) glass additives were densified below 950 °C via a solid-state route. Single orthorhombic phase and dense morphology were obtained with the LBSCA glass introduction. Promising microwave dielectric properties, especially with an improved Q × f value, were obtained in the Li3Mg2NbO6 ceramics with 0.5 wt% of the LBSCA glass addition sintered at 925 °C for 4 h: er = 15.16, Q × f = 90,557 GHz, τf = − 16.22 ppm/°C. It is suggested that the microwave dielectric performance was highly related to the densification, the polarizability, and the effects of the packing fraction. All experimental facts indicate that the LBSCA modified Li3Mg2NbO6 ceramics are potential candidates for Low-Temperature Co-fired Ceramic (LTCC) applications.

Temperature stability and chemical compatibility of novel Li1.6Zn1.6Sn2.8O8 ceramics

A new Li1.6Zn1.6Sn2.8O8 (LZS) ceramic with good temperature stability was synthesized by a simple solid-state reaction. The LZS ceramic exhibited nearly compact structure and possessed optimum dielectric characteristics of εr = 11.24, Q×f = 59800 GHz, τf = −7.86 ppm/°C. The influences of Li2O–B2O3–SiO2–CaO–Al2O3 (LBSCA) glass additive on the microwave dielectric characteristics, structure composition and morphology of LZS ceramics were investigated. The results demonstrated that LBSCA glass could significantly reduce sintering temperature and then suppress the appearance of impure phase SnO2. The scanning electron microscope (SEM) results indicated that the microstructure evolution from flake-like to particle-like appeared with increasing LBSCA, which was accompanied by the decline in grain sizes from 2.66 μm to 0.55 μm. The εr and Q×f exhibited trends resemble that of apparent densities. The variation of τf mainly originated from the large and negative τf of LBSCA glass. Particularly, the LZS-1.2 wt% LBSCA ceramic obtained at 925 °C displayed a compact and uniform microstructure and possessed optimum microwave dielectric characteristics of εr = 10.51, Q×f = 31700 GHz, τf = -7.93 ppm/°C. Moreover, LZS-1.2 wt% LBSCA ceramic exhibited favorable compatibility with silver, endowing the material with possible application in low temperature co-fired ceramic (LTCC).

Sm3+-doped CsPbBr3 NCs glass: A luminescent material for potential use in lighting engineering

Since being synthesized, CsPbX3 (X = Cl, Br or I) quantum dots (QDs) have gained increased interest due to their superior performances in photovoltaic applications. Herein, Sm3+-doped CsPbBr3 nanocrystallines (NCs) were successfully prepared in zinc borosilicate sodium (ZnO–B2O3–SiO2–Na2CO3, ZBSN) glass, and the as-prepared glass exhibited a strong red emission, which was attributed to the effects of the energy level transitions in Sm3+. Importantly, white light-emitting diodes (W-LEDs) were prepared by combining the glass with a blue InGaN chip, eliminating the need for a red phosphor to provide the red light, and white light was generated with a high colour rendering index (CRI: 82.6), a low correlated colour temperature (CCT: 4455 K) and colour coordinates in the white light region (0.3547, 0.3234). The glasses show excellent stability at 85 °C and 85% RH. Therefore, the Sm3+-doped CsPbBr3 NCs glass can be used as a colour converter for application in lighting engineering.

Novel bifunctional YAG:Ce3+ based phosphor-in-glasses for WLEDs by Eu2+ enhancement

A series of phosphor-in-glasses (PiGs) composed of different concentration of Y3Al5O12:Ce3+ (YAG:Ce3+) yellow phosphor and Eu2+ doped SiO2–B2O3–CaO–SrO luminescent glass matrix were fabricated by the low temperature co-sintering technology. Detailed measurements such as X-ray powder diffraction, thermal analysis, stable photoluminescence and decay time for the glass matrix, the phosphor and the PiGs were performed. Variable color rendering index, correlated color temperature, chromaticity coordinates and lumen efficiency of the white light emitting diodes (WLEDs) combined the PiGs with ultraviolet (UV) or blue chips were also recorded. The Eu2+ doped glass matrix emit blue light under the UV excitation due to the 4f65d1-4f7 transition of Eu2+ ion, so different from the conventional PiGs also embedded YAG:Ce3+ phosphors but only used for blue chips, the fabricated PiGs can act as bifunctional color converters for WLEDs to obtain blue and yellow emission simultaneously with different blue light sources pumped by UV and blue chips, respectively. The former blue light is from Eu2+ excited by UV radiation, while the latter is from blue chips indeed. The yellow emission intensity increases with more YAG:Ce3+ phosphors embedded along with the declining of the blue emission for the WLEDs pumped by both UV and blue chips, so 8 wt% YAG:Ce3+ based WLED show higher yellow emission intensity and the maximal lumen efficiency (about 46 lm/W), but the better concentration for the standard white light are lower, which are 2 wt% and 6 wt% for the WLEDs excited by UV and blue light with the chromaticity coordinates of (0.3180, 0.3539) and (0.3256, 0.3403), respectively. With the extended dual excitation mechanisms, the materials can be used potentially to be combined with other phosphors, particularly with non-nitride red phosphors for resin-free high power WLEDs.

Cerium influence on the thermal properties and structure of high-alkaline borosilicate glasses

The influence of cerium oxide on the thermal properties and the glass structure has been studied for the Li2O–(Na2O–K2O)–B2O3–SiO2 system. It has been established that cerium is completely soluble in the quenched glass during the synthesis if addition of CeO2 is 0–10 mol%. The cubic ceria phase is formed in glass either during the synthesis if addition of CeO2 is 20 mol% or after thermal treatment (annealing) if the glass contains 10–20 mol% of CeO2. The studied lithium borosilicate glasses have low thermal stability and demonstrate significant difference in the crystal phase formation for Ce-free and Ce-containing glasses after annealing. The lithium–sodium and lithium–potassium glasses have much higher thermal stability toward crystallization regardless of Ce content. The obtained results are relevant for improving the properties of matrix materials of similar borosilicate systems used for immobilization of radioactive waste.

The effects of Ca/Si ratio and B2O3 content on the dielectric properties of the CaO–B2O3–SiO2 glass–ceramics

CaO–B2O3–SiO2 (CBS) glass–ceramics were used as the main research object in this study. Based on the predecessors’ work, we optimized the ternary components of glass–ceramics to observe its effects on the structure, sintering performance and dielectric properties of glass–ceramics. When the content of B2O3 was 15.5 mol%, the Ca/Si ratio was 0.61–0.62, the glass–ceramics were transparent after water quenching, and it could achieve sintering densification under 850 °C. When the Ca/Si ratio was 0.62, the state of glass–ceramics was changed from transparent to milk-whited. As for sintering, when the sintering temperature was above 900 °C, they could achieve sintering densification. On the basis of it, we fixed the Ca/Si ratio of 0.61, and adjusted the content of B2O3. We found that with the increasing of the B2O3 content, the transparency of glass–ceramics was worse and worse, and when the samples obtained the highest density, the sintering temperature were elevated from 820 to 920 °C. According to the XRD analysis, with the B2O3 content added, the CaB2O4 crystal phases in the glass–ceramics was increased, so the permittivity of the glass–ceramics was increased. When the Ca/Si ratio was 0.61 and the B2O3 content was 15.5 mol%, the sintered density of CBS glass–ceramics was 2.42 g/cm3 at 850 °C, the permittivity and dielectric loss was er = 5.88, tanδ = 2.8 × 10−3 at 10 kHz.

Phase separated and porous glasses in the Na2O–B2O3–SiO2–Fe2O3 glass forming system

Phase separated and porous glasses in the Na2O–B2O3–SiO2–Fe2O3 glass forming system

Assessment of interatomic parameters for the reproduction of borosilicate glass structures via DFT‐GIPAW calculations

AbstractBorates and borosilicates are potential candidates for the design and development of glass formulations with important industrial and technological applications. A major challenge that retards the pace of development of borate/borosilicate based glasses using predictive modeling is the lack of reliable computational models to predict the structure‐property relationships in these glasses over a wide compositional space. A major hindrance in this pursuit has been the complexity of boron‐oxygen bonding due to which it has been difficult to develop adequate B–O interatomic potentials. In this article, we have evaluated the performance of three B–O interatomic potential models recently developed by Bauchy et al [J. Non‐Cryst. Solids, 2018, 498, 294–304], Du et al [J. Am. Ceram. Soc. https://doi.org/10.1111/jace.16082] and Edèn et al [Phys. Chem. Chem. Phys., 2018, 20, 8192–8209] aiming to reproduce the short‐to‐medium range structures of sodium borosilicate glasses in the system 25 Na2O x B2O3 (75 − x) SiO2 (x = 0‐75 mol%). To evaluate the different force fields, we have computed at the density functional theory level the NMR parameters of 11B, 23Na, and 29Si of the models generated with the three potentials and the simulated MAS NMR spectra compared with the experimental counterparts. It was observed that the rigid ionic models proposed by Bauchy and Du can both reliably reproduce the partitioning between BO3 and BO4 species of the investigated glasses, along with the local environment around sodium in the glass structure. However, they do not accurately reproduce the second coordination sphere of silicon ions and the Si–O–T (T = Si, B) and B‐O‐T distribution angles in the investigated compositional space which strongly affect the NMR parameters and final spectral shape. On the other hand, the core‐shell parameterization model proposed by Edén underestimates the fraction of BO4 species of the glass with composition 25Na2O 18.4B2O3 56.6SiO2 but can accurately reproduce the shape of the 11B and 29Si MAS‐NMR spectra of the glasses investigations due to the narrower B–O–T and Si‐O‐T bond angle distributions. Finally, the effect of the number of boron atoms (also distinguishing the BO3 and BO4 units) in the second coordination sphere of the network former cations on the NMR parameters have been evaluated.

Glass transition effect in liquation silicate\u2013borate\u2013phosphate glasses

Glass transformation effect of liquation glasses from the SiO2–B2O3–P2O5–K2O–MgO–CaO system was studied by DSC, SEM–EDS and 31P, 29Si and 11B MAS NMR spectroscopy methods. The relation between the B2O3 content in the analysed glasses and phase separation phenomenon, structure and glass transition effects was discussed. It was shown that increasing content of B2O3 causes the formation of P–O–BIII, P–O–BIV and Si–O–BIII and Si–O–BIV bonds which results in the appearance of liquation in analysed glasses. Simultaneously, double glass transition effect was observed with gradual decrease of Tg and Ea values. The observed relations were explained using crystalochemical parameters (iG, L) of chemical bonds present in the structure of analysed glasses.

Effects of Zn2+ substitution on the sintering behaviour and dielectric properties of Li2Mg1−xZnxSiO4 ceramics

Silicates, the basis on which low-temperature-fired dielectric materials widely studied for applications in the fields of microwave integrated circuits, have been developing vigorously owing to their low dielectric constants and tangent loss values. In this work, Zn2+ was gradually substituted to Mg2+ to make the sintering temperature decreased and enhance the microwave dielectric properties of Li2MgSiO4. Li2Mg1−xZnxSiO4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) powders were prepared through solid-state reaction. Aiming to decrease the sintering temperature to approximately 900 °C, 3 wt% Li2O–B2O3–SiO2–CaO–Al2O3 glass was used as a sintering aid. The XRD patterns made it clear that the major crystalline phase of the materials was Li2(Mg,Zn)SiO4. A new unexpected crystalline phase of ZnxSiO4 appeared when the amount of Zn2+ substituted increased to more than 0.4. SEM micrographs demonstrated that when x = 0.4, the most homogeneous microstructure appeared. Meanwhile, the Q × f value and the relative density also reached to their peaks when x = 0.4, respectively. Moreover, 3 wt% LBSCA-doped Li2Mg0.6Zn0.4SiO4 ceramics exhibited excellent dielectric properties of er = 5.89, Q × f = 44,787 GHz and τf = − 71.65 ppm/°C when sintered at 900 °C. The material exhibited low relative permittivity and low dielectric loss and could thus be a potential candidate for LTCC device applications.

Thermal conductivity of Na2O–B2O3–SiO2 melts

ABSTRACT Borosilicate glasses are candidate materials for the immobilization of high-level radioactive waste. The values of thermal conductivity of different borosilicate melts are thus indispensable information when optimizing the temperature distribution in a glass melting furnace. In this study, the thermal effusivity of Na2O–B2O3–SiO2 melts was measured using a front heating–front detection laser-flash method. The thermal conductivity, which can be obtained by combining the measured thermal effusivity with the specific heat capacity and density, was calculated using the least-squares method; the values for the Na2O–B2O3–SiO2 melts either slightly decreased linearly with increasing temperature or remained almost constant over the investigated temperature range. The values of thermal conductivity of the Na2O–B2O3–SiO2 melts were higher than those of B2O3–SiO2 melts and lower than those of CaO–B2O3–SiO2 melts. Furthermore, the thermal conductivity of the Na2O–B2O3–SiO2 melts was compared with those of the B2O3–SiO2 and CaO–B2O3–SiO2 samples.