CaO B2O3 SiO2 Research Articles

Low-fire Processing and Dielectric Properties of a Binary Crystallizable Glasses+alumina System

Abstract Crystallization kinetics and dielectric properties of a low-temperature, cofirable binary crystallizable glasses (CaO-Al2O3-SiO2 (CAS) and CaO-B2O3-SiO2 (CBS)) with alumina have been investigated. With alumina present, the bloating is minimized and wollastonite formed in the binary crystallizable glasses is replaced by anorthite. With increasing amount of anorthite formed in the ternary alumina+CAS glass+CBS glass dielectric composite, the dielectric constant remains relatively unchanged but the dielectric loss decreases as sintering is extended.

Effects of LiF on sintering behavior and properties of CaO-B2O3-SiO2 dielectric ceramics obtained by solid-state reaction

Li-added CaO-B2O3-SiO2 (CBS) dielectric microwave substrates for low temperature co-fired ceramic (LTCC) applications were prepared using a solid-state reaction, and the effect of the LiF additive on the sintering behavior, dielectric performance and mechanical properties of the product was investigated. In this presently reported work, we found that the LiF additive could effectually reduce the sintering temperature of the CBS ceramics and also substantially improved the densification, dielectric and mechanical properties of it. The experimental results showed that an addition of 3 wt% LiF to the sample sintered at 790 °C resulted in a main crystalline phase of β-CaSiO3 which had excellent proprieties. These included an excellent degree of densification, εr of 6.43, tan δ of 5.9 × 10−4 and a volume resistivity of 8.20 × 1011 Ω cm at 1 MHz, and flexural strength of 241 MPa.

Carbon nanotube/graphene oxide‐added CaO‐B2O3‐SiO2 glass/Al2O3 composite as substrate for chip‐type supercapacitor

AbstractA CaO‐B2O3‐SiO2 (CBS) glass/40 wt% Al2O3 composite sintered at 900°C exhibited a dense microstructure with a low porosity of 0.21%. This composite contained Al2O3 and anorthite phases, but pure glass sintered at 900°C has small quantities of wollastonite and diopside phases. This composite was measured to have a high bending strength of 323 MPa and thermal conductivity of 3.75 W/(mK). The thermal conductivity increased when the composite was annealed at 850°C after sintering at 900°C, because of the increase in the amount of the anorthite phase. 0.25 wt% graphene oxide and 0.75 wt% multi‐wall carbon nanotubes were added to the CBS/40 wt% Al2O3 composite to further enhance the thermal conductivity and bending strength. The specimen sintered at 900°C and subsequently annealed at 850°C exhibited a large bending strength of 420 MPa and thermal conductivity of 5.51 W/(mK), indicating that it would be a highly effective substrate for a chip‐type supercapacitor.

Manufacturing a high performance film of CaO-B2O3-SiO2 glass-ceramic powder with surface modification for LTCC application

The present work was oriented to develop a high-performance film for LTCC application through using a kind of silane coupling agent (SCA) to modify the CBS (CaO-B2O3-SiO2) glass-ceramic powders in tape casting process. The coupling mechanism of the silane coupling agent interacting with the powders was illustrated in detail, and the optimum amount of additions was determined by the infrared transmittance and contact angle experiment. The rheological properties of suspensions, the compactness and tensile breaking strength of the green tape were texted by using a number of quantitative and qualitative instruments. Furthermore, when the green tapes sintered at 820°C, the sintering characteristics and microwave properties of sintered body with different SCA additions was also analyzed. Based on the experimental results, it revealed that the powders modified by SCA with 1.5wt% additions could induce the most excellent performance of film, with the density at 1.57g/cm3 and the tensile strength at 2.57MPa, possessing the highest density and best microwave properties of sintered body: the density of sintered body was 2.48g/cm3, the dielectric constant and dielectric loss was εr=5.93, tanδ=8×10−4 at 12Hz.

Construction and nonlinear optical characterization of CuO quantum dots doped Na2O–CaO–B2O3–SiO2 bulk glass

The spherical shape copper oxide (CuO) quantum dots (QDs) were successfully fabricated via copper basic calcium sodium borosilicate (Na2O–CaO–B2O3–SiO2) precursor obtained with a facile sol–gel technique. The microstructural analysis of doped QDs are systemically characterized, such as transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photo-electron spectroscopy. And the results reveal that the CuO QDs with the small size are well dispersed doped in sodium calcium borosilicate glass. Remarkably, the CuO glass materials exhibit the good third-order optical nonlinear susceptibility χ(3) (1.379 × 10−12 esu), which was investigated by femto-second Z-scan technique at the wavelength of 1550 nm, pulse duration of 50 fs, repetition rate of 50 MHz. The glass hybrids displayed a reverse saturable absorption and self-focusing refraction performance. And the mechanism to explain the third-order nonlinearity of CuO glass may be predominantly originated from the surface plasmon resonance effect, the quantum confinement effect and partly from the thermal effect. Besides, it is interesting that the glass hybrids have significant nonlinear absorption effects that endow the material to the potential value of the application of optical limiting device.

Glass structure, phase transformation and microwave dielectric properties of CaO–B2O3–SiO2 glass–ceramics with addition of La2O3

The CaO–B2O3–SiO2 (CBS) glasses with addition of xLa2O3 (0 ≤ x ≤ 20 wt%) were prepared by conventional quenching method, the glass structure, phase transformation and microware dielectric properties were studied. The glass structure analysis by magic angle spinning nuclear magnetic resonance (MAS-NMR) and infrared (IR) spectroscopy indicated that [BO4] transformed into [BO3] and the proportion of Si–O–Si bridge oxygen bond in [SiO4] tetrahedrons decreased obviously with the addition of La2O3. The differential thermal analysis (DTA) revealed that the CBS glass system kept better glass-forming ability and the transition temperature (Tg) decreased from 743 to 724 °C after addition of La2O3. As the content of La2O3 increases, the crystallization tendency of CaB2O4 is suppressed, while that for Ca2SiO4 is promoted. With appropriate content of La2O3 (5 wt%), the sample possess excellent dielectric properties (er ≈ 4.1, tanδ ≈ 1.7 × 10−3 at 15 GHz). The variations of dielectric properties are believed to be appreciably associated with the relative content of the phases present.

Glass structure of the CaO–B2O3–SiO2–Al2O3–ZnO glasses system with different Si content

The aim of the present work is to investigate the effects of SiO2 content on the structure of CaO–B2O3–SiO2–Al2O3–ZnO glass using the MAS-NMR, the fourier transform infrared spectrometer and differential scanning calorimetry (DSC). The results showed that the majority of Al existed in fourfold coordination and Zn acted as glass modifier in glass structure. With the increasing of SiO2 content, the relative amount of BIII units decreased while the BIV units increased and the proportion of Si–O–Si bridge oxygen bond in [SiO4] tetrahedrons increased obviously. The DSC curves revealed that the glass transition temperature increased from 732 to 773 °C with the increasing of SiO2 content, indicating that SiO2 generating more bridge oxygen can increase the degree of polymerization of glass structure.

Structure and crystallization behavior of Al containing glasses in the CaO–B2O3–SiO2 system

The aim of the present work is to investigate the effects of Al2O3 content on both the structure and crystallization behavior of CaO–B2O3–SiO2 (CBS) glass composition using NMR, FT-IR and DSC.

The Influence of Sintering Temperature on the Microwave Dielectric Properties of Mg2SiO4 Ceramics with CaO-B2O3-SiO2 Addition

Conventional solid-state methods were used to synthesize Mg2SiO4 ceramic at relatively low sintering temperatures with the assistance of CaO-B2O3-SiO2 (CBS) glass. The effects of the CBS additions on the sintering behavior, crystal structures, microstructures, and microwave dielectric properties of Mg2SiO4 ceramic have been investigated in detail. The results indicate that the addition of CBS glass lowered the sintering temperature of Mg2SiO4 ceramic significantly. The Mg2SiO4 ceramic with 7 wt.% CBS addition sintered at 1325°C for 4 h shows excellent microwave dielectric properties: e r = 6.47, Q × f = 16,552 GHz, τ f = −23.34 ppm/°C.

Synthesis and characterization of LTCC compositions with middle permittivity based on CaO-B2O3-SiO2 glass/CaTiO3 system

CaTiO3 ceramics with the addition of CaO-B2O3-SiO2 (CBS) glass (45–55wt%) composites were sintered at 830°C, 850°C, 875°C and 900°C. To illustrate influence mechanism of the different glass contents and sintering temperatures on the properties of the composites, we focused on the multiple performances of the composites by employing different qualitative and quantitative instruments. Composites with 50wt% glass sintered at 875°C presented fairly ideal performance: the bulk density was 3.20g/cm3, the dielectric constant was 25.7 and the dielectric loss was 0.0009 at 7GHz. Micro-Structure analysis of the composites showed a dense and pore-less microstructure except for few pores with size around 1μm. In addition, the composite could meet the shrinkage requirement of Ag electrodes and could not possibly react with Ag electrodes any more. This makes them suitable for various dielectric applications at low sintering temperature.

Densification Behavior and Dielectric Properties of CaO-B<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> System Glass-Ceramics Containing ZrO<sub>2</sub>

CaO–B2O3–SiO2 (CBS) glass-ceramics containing ZrO2 were prepared by conventional melting and heat treated crystallization method. The effects of ZrO2 on the crystallization behavior, sintering characterization and dielectric properties of the glass-ceramics were analyzed respectively. The results indicated that ZrO2 addition can improve the crystallization and densification of CBS glass-ceramics. The major crystallized phase of sample with≥7wt% ZrO2 was cyclowollastonite (α-CaSiO3).It is found that the optimal sintering condition for the glass-ceramics is 770 oC for 30min. CBS glass ceramics sample with 7wt% ZrO2 shows the best sintering characterization and dielectric properties (ρ= 2.71g/cm3, εr ≈8.8,tan δ=2.36×10-3 at 1 MHz), which is supposed to be suitable for LTCC application.

Effects of CaO–B2O3–SiO2 glass additive on the microstructure and electrical properties of BCZT lead-free ceramic

Addition of CaO–B2O3–SiO2 (CBS) glass was performed to lower the sintering temperature of lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics. Orthorhombic and tetragonal phases coexisted in CBS-free BCZT ceramics. The BCZT ceramics transformed into a pseudo-cubic phase when sintered at 1300°C with increasing CBS glass content. Additionally, the secondary phase, Ba2TiSi2O8, was observed when CBS glass was added. The density initially increased, reached a maximum value with 2wt% CBS glass, and then decreased rapidly with further increase in CBS glass content, which was consistent with the microstructure. The ɛ, Tc, Pr, and d33 depend on microstructure, and the results agree with the density. Evident relaxation behavior was observed. Observed results were inferred to be dependent on the microstructure, phase structure, lattice distortion, and secondary phase. The sample with 2wt% CBS glass showed the excellent performance, which could be a promising substitute to lead-free piezoelectric ceramics for lead-based materials.

Structure and luminescence of Dy3+ doped CaO–B2O3–SiO2 glasses

The present work reports structure and luminescence of Dy3+ doped CaO–B2O3–SiO2 glasses prepared by melt quenching technique. The presence of various stretching and bending vibrations of different borate and silicate groups were identified from FTIR spectral measurements. The optical absorption and luminescence spectra were also measured, and their emission spectra exhibit two intense emission bands at around 485nm (blue) and 577nm (yellow) corresponds to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions, respectively. The emission spectra were characterized through CIE 1931 color chromaticity diagram to explore its suitability for W-LED applications. Furthermore, the proper Y2O3 could change local structure of glass, which makes the UV absorption edge shift to longer wavelength, and it's easier to transfer energy from host to Dy3+ and then enhance the emission of Dy3+.

Effect of SrTiO3 on the properties of CBS glasses/Al2O3 ceramics

The effects of SrTiO3 on the sintering behaviors, phase structures, microstructures and the microwave dielectric properties of CaO–B2O3–SiO2 (CBS) glasses/Al2O3 ceramics were investigated in this study. The results show that the SrTiO3 additions can be well sintered with CBS glasses/Al2O3 ceramics at low temperature, and increase the density and the dielectric constant of the CBS glasses/Al2O3 ceramics. Especially, the temperature coefficient of the resonant frequency τf could be adjusted to zero with SrTiO3 added. And the sample with 15 wt% SrTiO3 sintered at 850 °C exhibited promising properties of: er = 10.13, tanδ = 0.00323, τf = −5.35, and σ ≥ 200 MPa.

Structure–composition relationships of bioactive borophosphosilicate glasses probed by multinuclear11B,29Si, and31P solid state NMR

By combining11B,29Si, and31P nuclear magnetic resonance (NMR) experimental results, we present the first comprehensive structural investigation of 15 borophosphosilicate (BPS) glasses of the Na2O–CaO–B2O3–SiO2–P2O5system.

A route for white LED package using luminescent low-temperature co-fired ceramics

This paper presents a systematic investigation to develop a novel kind of luminescent low-temperature co-fired ceramics (LTCC) for white LED package. The material used was the CaO–B2O3–SiO2 glass-ceramics doped with Dy3+ prepared by a sol–gel process. The characterization for its sintered bodies was associated with photoluminescence, XRD, SEM, and microwave dielectric measurement method. The results reveal that the optimal luminescent properties of sintering bodies and the microstructure with Ca2SiO4 and SiO2 can be obtained at the sintering temperature of 875 °C. Our results indicated that under 352 nm UV light exciting, the emission spectra of the glass-ceramics consist of two emission bands: the blue band (487 nm) and yellow band (573 nm), with chromaticity coordinates right in white-light region. The obtained products show the dielectric constant approximate 5.70, dielectric loss about 0.012 at 1 MHz. This provides great potentials for the application in microelectronic LED packaging.

The size-effect of Al2O3 on the sinterability, microstructure and properties of glass-alumina composites

The glass-ceramic composites were prepared from low-softening glass CaO–B2O3–SiO2, micrometer and nanometer alumina. The influences of nano-Al2O3 on the sinterability, microstructure, dielectric property, mechanical strength, and thermal expansion of glass-alumina composites were investigated. The densification mechanism of nano-Al2O3 modified glass-alumina composites was revealed further. The results show that nano-Al2O3 effectively lowers the densification temperature of glass-alumina ≤900°C. The density gradually increases with increasing nano-Al2O3 to 15 wt %, and then decreases. Dielectric constant, dielectric loss, and flexural strength respectively versus nano-Al2O3 exhibit a similar change trend to the density. The sample with 15 wt % nano-Al2O3 sintered at 900°C could form the dense microstructure (~2.95 g/cm3) and achieve the high performance: low dielectric constant (6.13), low dielectric loss (5.2 × 10−4), low thermal expansion (4.21 × 10−6/°C), and high mechanical strength (178 MPa).

Crystallization, sinterability and dielectric properties of CaO–B2O3–SiO2 glass ceramics with Al2O3 additives

Glass–ceramic materials of the CaO–B2O3–SiO2 (CBS) system added with various amounts of Al2O3 have been prepared by conventional melting and heat treated crystallization method. The effects of Al2O3 on the sintering characterization and dielectric properties have been investigated. With increasing the Al2O3 content, the bending and stretching vibrations in [SiO4]2− became weak. XRD patterns of samples with ≥3 wt% Al2O3 introduce cyclowollastonite (α-CaSiO3) as single crystallized phase of sintered glass–ceramics. It is found that the optimal sintering temperature for this glass ceramics is 800 °C for 30 min, and the sinterability was obviously improved by Al2O3 additive. CBS glass ceramics sample with 5 wt% Al2O3 achieved the best sintering characterization and dielectric properties (er ≈ 7, tan δ = 1.9 × 10−3 at 1 MHz), which is proposed to be suitable for LTCC application.

Study on the physics and dielectric property of K2O–B2O3–SiO2/Al2O3 glass + ceramic

Effects of different glass/ceramic weight ratio on the physics and dielectric properties of Al2O3–B2O3–SiO2 (ABS) glass/Al2O3 ceramic composites were investigated. The results show that when glass/ceramic = 50:50 (mass fraction), the composite had the excellent comprehensive properties. Then the lower softening temperature CaO–B2O3–SiO2 (CBS) glass was added to the ABS glass as sintering flux on this composite. When the CBS glass content was 2 wt%, the composites showed good properties: er = 4.98, tanδ = 3.59 × 10−3 (which was 10 % lower than sample without CBS glass), and the flexural strength was 154.77 MPa (which was 16.2 % higher than the sample without CBS glass).

Low temperature sintering and dielectric properties of Li2ZnTi3O8–TiO2 composite ceramics doped with CaO–B2O3–SiO2 glass

The effects of CaO–B2O3–SiO2 (CBS) glass addition on the sintering temperature and dielectric properties of Li2ZnTi3O8–TiO2 (LZT) composite ceramics have been investigated. Due to the compensating effect of rutile TiO2 (τf ≈ +450 ppm/ °C), the temperature coefficient of resonant frequency (τf) for Li2ZnTi3O8 + 4 wt% TiO2 with biphasic structure was adjusted to a value near zero. The pure LZT ceramics were usually sintered at high temperature of about 1,160 °C. It was found in our experiment that a small amount of CBS glass additives could effectively lower the sintering temperature of LZT ceramics to 900 °C. With increasing the content of CBS glass, both of dielectric constant (er) and quality factor (Q × f) value decreased. Typically, the 1 wt% CBS glass added Li2ZnTi3O8 + 4 wt% TiO2 ceramic sintered at 900 °C for 4 h exhibited good microwave dielectric properties of er = 26.9, Q × f = 23,563 GHz and τf = −1.5 ppm/ °C, which made it promising for low temperature co-fired ceramics technology application.