BaO B2O3 SiO2 Glass Research Articles

Fabrication of sapphire/MgAl2O4/sapphire laminated transparent composite by brazing with BaO–B2O3–SiO2 glass filler

For improving the mechanical properties of MgAl2O4 ceramic and maintaining its wide band transparency, the sapphire/MgAl2O4/sapphire laminated transparent composites with thin sapphire layers were fabricated by brazing with BaO–B2O3–SiO2 (BBS) glass filler. The BBS glass filler had an appropriate CTE (coefficient of thermal expansion) value and good wettability on the surface of sapphire and MgAl2O4 ceramics. Joining experiments were first carried out to optimize the preparation process parameters of laminated composites. The results indicated that high bonding temperature promoted mutual dissolution and diffusion of BBS glass and MgAl2O4 ceramic, but led to the intergranular infiltration of glass filler and the formation of pores due to volatilization of B2O3. When the bonding temperature was 1000 °C, the sapphire/MgAl2O4 joints with the best transparency and acceptable shear strength could be obtained. On this basis, the laminated composites with 0.15 mm thick sapphire layers were fabricated by brazing using BBS glass at 1000 °C. The flexural strength of the laminated composite reached 320 ± 10 MPa, which was higher than that of MgAl2O4 (195 ± 15 MPa). The in-line transmittance of laminated composite was 80.9 % at 1000 nm, which was slightly lower than that of MgAl2O4 (82.2 %).

Anti-acid corrosion mechanism of yttrium oxide doped barium borosilicate glass

Designing glass with excellent acid resistance is a prerequisite for developing high-performance terminal electrode pastes. Herein, we fabricated Y2O3 doped BaO–B2O3–SiO2 glass with excellent anti-sulfuric acid corrosion properties. The anti-corrosion mechanism of glass in acid environment was investigated by spectra and microstructure analysis. The passivating gel layer with a porous structure was formed on the glass surface during the corrosion process. The average pore diameter of the porous gel could be reduced by increasing the content of Y2O3. The smaller pore size of the porous gel would considerably increase the collision frequency between solvent molecules and the pore wall, which could effectively inhibit the ion migration in the gel layer, reduce the corrosion rate, and improve the acid resistance of the glass. This study contributes to the understanding of the corrosion mechanism of the glass and provides theoretical guidance for rationally designing anti-acid corrosion glass for terminal electrode pastes.

A Systematic Study on the Structure and Dielectric Properties of BaO–B2O3–SiO2 Glass Additive in Ba(Fe0.5Nb0.5)O3 Ceramics

A Systematic Study on the Structure and Dielectric Properties of BaO–B₂O₃–SiO₂ Glass Additive in Ba(Fe_0.5Nb_0.5)O₃ Ceramics

Preparation and properties of antioxidative BaO–B2O3–SiO2 glass-coated Cu powder for copper conductive film on LTCC substrate

In this study, uniform BaO–B2O3–SiO2 glass coatings on micro Cu powders with different glass/Cu ratio were prepared by sol–gel method. The pastes prepared with the glass-coated Cu powders were screen printed on low temperature co-fired ceramic (LTCC) substrate. Then the dry films on substrate were binder-burned-out at 400 °C in air and co-fired at 910 °C in N2 atmosphere. During the binder-burning-out process, the oxidization of the films with 9 and 11 wt% glass was slight because of the improvement of oxidization resistance of the glass-coated Cu powders. Moreover, the sintered film with 9 wt% glass coating showed no crystal phase of copper oxide and had small sheet resistance of 1.3 mΩ/□, which can be used as good conductive thick film on LTCC substrate for microelectronic packaging.

Microstructures and Energy Storage Properties of Sr0.5Ba0.5Nb2O6 Ceramics with BaO–B2O3–SiO2 Glass Addition

Sr0.5Ba0.5Nb2O6 (SBN) ceramics with the BaO–B2O3–SiO2 (BBS) glasses have been successfully produced for high energy-storage density capacitor applications. The phase evolution, microstructures, dielectric properties and energy storage properties of the SBN-based glass ceramics were investigated. X-ray diffraction analysis revealed all ceramic samples were of tetragonal tungsten bronze-type structures. As the mass ratio of glass in the glass ceramics increased from 0.1wt.% to 10 wt.%, the dielectric constant of the glass ceramics increased initially and then decreased with the increasing glass content. Compared to pure Sr0.5Ba0.5Nb2O6 ceramics, the glass ceramics with a small amount of BBS glass addition illustrated better energy storage properties. The glass-ceramic with 0.5wt. % BBS glass addition showed the highest breakdown strength of 194 kV/cm and a maximum energy storage density of 0.286 J/cm3.

Microstructures and energy-storage properties of (1 − x)(Na0.5Bi0.5)TiO3–xBaTiO3 with BaO–B2O3–SiO2 additions

A series of (1 − x)(Na0.5Bi0.5)TiO3–xBaTiO3 (abbreviated as NBT–xBT) (x = 0, 0.01, 0.05, 0.1, 0.15) ceramics with 3 mol% BaO–B2O3–SiO2 glass additives were prepared via the solid state reaction route. Effect of the BaTiO3 content on microstructures, phase evolution, dielectric, and ferroelectric and energy storage properties of NBT–xBT glass ceramics has been investigated. X-ray diffraction studies of NBT–xBT ceramics with glass of 3 mol% were a perovskite structure without the secondary phase. With increasing BaTiO3 additive in the ceramics, the dielectric constant and the dielectric breakdown strength exhibited a gradual increase firstly and then slightly decrease. The addition of 5 mol% BaTiO3 to the ceramics improved the dielectric constant and energy storage properties remarkably, and the maximum recoverable discharged energy density of 0.68 J/cm3 with an energy efficiency of 71 % was obtained by the sintering at 1035 °C.

Preparation of LTCC materials with adjustable permittivity based on BaO–B2O3–SiO2/BaTiO3 system

This paper studied the preparation and characterization of LTCC (low temperature co-fired ceramics) materials based on BaO–B2O3–SiO2/BaTiO3 glass–ceramics, where the sintering temperature was about 900°C and dielectric constant was effectively adjustable from 5 to 30 by changing the BaTiO3 fraction from 60wt% to 90wt%. X-ray diffractometer (XRD), scanning electron microscopy (SEM) were used to examine the effect of different amounts additive on the dielectric properties of this LTCC system and the crystal structure change. The results indicated that BaTiO3 can be used as a dielectric additive aim to adjust the permittivity of BaO–B2O3–SiO2 glass, which the main influence factors on dielectric are the contents of the secondary phase, the BaTiO3 phase fraction and the porous structure of the sintered body. Therefore, the microstructure and dielectric property of BaO–B2O3–SiO2/BaTiO3 glass–ceramics composites could be controlled by adjusting the content of BaTiO3 additive.

Effects of BaO–B2O3–SiO2 glass additive on dielectric properties of Ba(Co0.5Nb0.5)O3 ceramics

Ba(Co0.5Nb0.5)O3 (BCN) ceramics doped with BaO–B2O3–SiO2 (BBS) glass were prepared by the conventional solid-state ceramic route. The effects of glass content on the sintering temperature, phase composition, microstructure and dielectric properties of Ba(Co0.5Nb0.5)O3 ceramics were investigated. The sintering temperature of the BaO–B2O3–SiO2 glass added Ba(Co0.5Nb0.5)O3 ceramics decreased by 75–125°C than that of the pure Ba(Co0.5Nb0.5)O3. The addition of BaO–B2O3–SiO2 glass can improve the frequency stability of the dielectric properties of Ba(Co0.5Nb0.5)O3 and decrease dielectric loss. Ba(Co0.5Nb0.5)O3 ceramics with 0.5wt% BaO–B2O3–SiO2 glass additions show the best frequency stability and the lowest dielectric loss, and the dielectric constant is almost as same as the pure Ba(Co0.5Nb0.5)O3 ceramic. These improvements in the dielectric characteristics of Ba(Co0.5Nb0.5)O3 ceramics have great scientific significance for their applications.

Effects of BaO–B2O3–SiO2 glass additive on dielectric properties of Ba(Fe0.5Nb0.5)O3 ceramics

Ba(Fe0.5Nb0.5)O3 (BFN) ceramics doped with BaO–B2O3–SiO2 (BBS) glass were prepared by the conventional solid-state ceramic route. The effects of glass content on the sintering temperature, phase composition, microstructure, dielectric properties and breakdown strength of Ba(Fe0.5Nb0.5)O3 ceramics were investigated. The sintering temperature of the BaO–B2O3–SiO2 glass added Ba(Fe0.5Nb0.5)O3 ceramics decreased by 150–330°C than that of the pure Ba(Fe0.5Nb0.5)O3. The addition of 5wt% BaO–B2O3–SiO2 glass reduces the dielectric loss at 1kHz from 1.5 to 0.019. Glass addition as high as 5wt% shows the highest breakdown strength of 27.12kV/cm, which is approximate 30 times higher than that of pure Ba(Fe0.5Nb0.5)O3.

Microstructure and energy-storage performance of BaO–B2O3–SiO2 glass added (Na0.5Bi0.5)TiO3 thick films

(Na0.5Bi0.5)TiO3 lead-free thick films were successfully fabricated on alumina substrates via a screen printing method with 0–10 wt% BaO–B2O3–SiO2 glass addition. Microstructure, dielectric properties and energy-storage performance of the thick films were systematically investigated. The results show that the denser thick films were obtained by addition of glass. Thus, the breakdown strength, the energy-storage density and efficiency were greatly improved. The maximum recoverable energy-storage density and efficiency of sample with 1 wt% glass were 2.0 J/cm3 and 44.1 %, respectively. Meanwhile, a low leakage current density of about 10−6 A/cm2 was obtained for all samples at 100 kV/cm.

Spherical shape Ba-based glass powders prepared by spray pyrolysis for MLCCs

Spherical shape BaO–B2O3–SiO2 glass powders were directly prepared by high temperature spray pyrolysis at >1000 °C. The thermal and morphological characteristics of the prepared glass powders were investigated. The glass powders prepared at temperature of 1000 °C had spherical shape and hollow inner structure. On the other hand, the powders prepared at high temperature of 1300 °C had complete spherical shape and dense inner structure by complete melting. The mean size of the glass powders was 0.9 μm. The glass transition temperatures (Tg) of the glass powders obtained by spray pyrolysis at preparation temperatures between 1000 and 1300 °C were 601.1 °C regardless of the preparation temperatures. The specimen of the glass powders obtained by spray pyrolysis at the preparation temperature of 1300 °C had small number of voids even at low sintering temperature of 700 °C. In addition, the specimen sintered at temperature of 800 °C had dense microstructure without voids.

Microstructure and dielectric properties control of Ba4(Nd0.7Sm0.3)9.33Ti18O54 microwave ceramics

Abstract Microwave ceramics of Ba4(Nd0.7Sm0.3)9.33Ti18O54 with 0–3 wt% Ag additions were synthesized by a citrate sol–gel method. The BaO–B2O3–SiO2 glass was also added into the sol–gel derived BNST ceramic powders as sintering aids. The undoped, Ag- and BaBS-doped samples can be sintered at 1250 °C, 1150 °C and 1000 °C, respectively. The microstructure and dielectric properties were then controlled by doping Ag or BaBS glass. Near isoaxial grains with about 250 nm and typical columnar grains were obtained for the silver-doped and BaBS-doped samples, respectively. For the

Surface modification and crystallization of the BaO–B2O3–SiO2 glassy system using CO2 laser irradiation

The surface modification and crystallization process of BaO–B2O3–SiO2 glass compositions when exposed to CO2 laser irradiation was evaluated as a function of the laser power, irradiation time and surface condition. The glass surface was modified by the application of laser power exceeding 0.40W and an irradiation time of more than 300s. Micro-Raman and X-ray diffraction measurements revealed at high laser power the formation of β-BaB2O4 (β-BBO) crystalline phase. The crystallization of the irradiated region was enhanced when β-BBO micrometer sized particles were dispersed on the surface of the glass sample. The intensity of the second harmonic generation observed in the crystallized region was found to depend mainly on the condition of the glassy surface prior to glass irradiation.

Compositional Design of Lead-Free, Low-Temperature Cofired Ceramic Dielectric Composite

Compositional design and properties of a lead-free, low-temperature cofired ceramic (LTCC) system containing a crystallizable K2O–CaO–SrO–BaO–B2O3–SiO2 glass, alumina and titania have been investigated. The ternary composites with a high sintered density of >95% can be obtained at 875 °C. Compositions with tailor-made properties are designed according to a working model based on the assumption of the mixing rule, and validated with experimental results. The resulting lead-free composites exhibit a dielectric constant of 7.7–20.0 at 1 MHz, and a thermal expansion coefficient of (5.37–7.22)×10-6/°C.

Effects of Alumina on Devitrification Kinetics and Mechanism of K2O–CaO–SrO–BaO–B2O3–SiO2 Glass

Effects of alumina on the devitrification kinetics and mechanism of a low-dielectric K2O–CaO–SrO–BaO–B2O3–SiO2 glass powder have been investigated. Crystalline phases including cristobalite (SiO2) and pseudowollastonite [(Ca, Ba, Sr)SiO3] are formed during the firing of the pure glass. With added alumina content greater than a critical value, e.g., 10–20 vol% at 900–1000°C, the above crystalline phases are completely prevented but anorthite [(Ca, Sr, Ba)Al2Si2O8] is formed. This result is attributed to the dissolution of alumina into the glass. The dissolution changes the composition of the glass to become aluminum-rich, and the dissolution kinetics of alumina into the glass is far too rapid compared with the formation of cristobalite and pseudowollastonite. The crystallization kinetics of anorthite follows the analysis of the Avrami equations, and the results show an apparent activation energy close to that of the Al–O bond strength, suggesting a reaction-controlled kinetics.

Sintering of a Crystallizable K2O–CaO–SrO–BaO–B2O3–SiO2 Glass with Titania Present

Crystallization and reaction kinetics of a crystallizable K2O–CaO–SrO–BaO–B2O3–SiO2 glass powder with 17–40 vol% titania powder were investigated. The initially amorphous K2O–CaO–SrO–BaO–B2O3–SiO2 glass powder formed cristobalite (SiO2) and pseudowollastonite [(Ca, Ba, Sr)SiO3] during firing. The above crystalline phases were completely replaced by a crystalline phase of titanite [(Ca, Sr, Ba)TiSiO5] when the amount of added titania was greater than a critical value, e.g., 10 vol%, at 99–1100 °C. A chemical reaction taking place at the interface between titania and the glass was attributed to the above observation. The dissolved titania changed the composition of the glass, and the dissolution kinetics was much faster than the formation of cristobalite and pseudowollastonite. Activation energy analysis showed that the crystallization of titanite [(Ca,Sr,Ba)TiSiO5] was controlled by a reaction-limiting kinetics of formation for the Ti–O bond.