ZnO B2O3 Research Articles

ChemInform Abstract: Effect of Glass Additions on BaO-TiO2-WO3 Microwave Ceramics.

The effect of glass addition on the properties of BaO–TiO2-WO3 microwave dielectric material N-35, which has Q= 5900 and K= 35 at 7.2 GHz for samples sintered at 1360°C, was investigated. Several glasses including B2O3, SiO2, 5ZnO–2B2O3, and nine other commercial glasses were selected for this study. Among these glasses, one with a 5 wt% addition of B2O3 to N-35, when sintered at 1200°C, had the best dielectric properties: Q= 8300 and K= 34 at 8.5 GHz. Both Q and K increased with firing temperature as well as with density. The Q of N-35, when sintered with a ZnO–B2O3 glass system, showed a sudden drop in the sintering temperature to about 1000°C. The results of XRD, thermal analysis, and scanning electron microscopy indicated that the chemical reaction between the dielectric ceramics and glass had a greater effect on Q than on the density. The effects of the glass content and the mixing process on the densification and microwave dielectric properties are also presented. Ball milling improved the densification and dielectric properties of the N-35 sintered with ZnO–B2O3.

Microstructure and microwave dielectric properties of ZnO-B2O3 added (Ca0.254Li0.19Sm0.14)TiO3 ceramics

The effects of ZnO-B2O3 (ZB2) on the sintering behavior and microwave dielectric properties of (Ca0.254Li0.19Sm0.14)TiO3 ceramics were investigated. The densities of the specimens reached the maximum value by adding 3 wt.% ZB2 and then decreased. The sintering temperature of the specimens was lowered from 1300 to 1100°C without degradation of the microwave dielectric properties. The (Ca0.254Li0.19Sm0.14)-TiO3 + 3 wt.% ZB2 sintered at 1100°C for 3 h showed good microwave dielectric properties, ɛ r = 108.2, Q f = 6545 GHz, and τ f = 6.5 ppm/°C, respectively, indicating that ZB2 was an effective sintering aid to improve the densification and microwave dielectric properties of (Ca0.254Li0.19Sm0.14)TiO3 ceramics.

Failure Mechanism of a Low‐Temperature‐Cofired Ceramic Capacitor with an Inner Ag Electrode

Failure mechanism of a multilayer ceramic capacitor (MLCC) made of a low‐fire BaNd2Ti4O12(BNT)+ZnO–B2O3 (ZB) dielectric with an inner pure silver electrode at elevated temperatures and voltages has been investigated. A nonlinear current–voltage leakage characteristic is found when the degradation of MLCC occurs, and the time to failure decreases with increasing either the temperature or the voltage. Results of microstructure, composition, and impedance analyses reveal that the failure is caused by silver diffusion in the ZB glass during sintering and highly accelerated life test.

Silver Co‐Firable ZnTiNb2O8 Microwave Dielectric Ceramics with Li2O–ZnO–B2O3 Glass Additive

The effects of Li2O–ZnO–B2O3 glass additive on the sintering behavior, phase formation, microstructure, and microwave dielectric properties of ZnTiNb2O8 ceramics have been investigated. The sintering temperature of ZnTiNb2O8 ceramics can be effectively reduced from 1200°C to 875°C by adding a small amount of Li2O–ZnO–B2O3 glass, while no obvious degradation of the microwave dielectric properties was induced. Typically, the 2.0 wt% Li2O–ZnO–B2O3 glass‐added ceramic sintered at 875°C has better microwave dielectric properties of ɛr=31.8, Q×f=25,013 GHz, and τf=−62 ppm/°C. In addition, the ceramics can be co‐fired well with an Ag electrode.

Synthesis and characterization of Bi2S3 nanocrystals in glass matrix

This is the first evidence for the successful growth of Bi2S3 nanocrystals in glass matrix (SiO2–K2O–Na2O–B2O3–ZnO–TiO2) using the fusion method. Different sizes of nanocrystals in glass matrix were grown by annealing the glass (dispersed with Bi2S3 nucleons) under two different conditions. The glass was annealed between 6 and 48 h at constant temperature 550 °C. The glass was also annealed at the temperature between 550 and 600 °C at constant annealing time 6 h. The Bi2S3 nanocomposite obtained was characterized by optical transmission (OT) spectroscopy and transmission electron microscopy (TEM). OT spectroscopy revealed strong red shift in transmission cut off which indicates increase in particle size of nanocrystals under both the conditions. TEM analysis demonstrated the nanocrystal size in the range of 2–5 nm.

Eu-doped B2O3–ZnO–PbO glass phosphor powders with spherical shape and fine size prepared by spray pyrolysis

Eu-doped B2O3–ZnO–PbO glass phosphor powders with spherical shape and fine size were directly prepared by spray pyrolysis. The glass phosphor powders prepared at a temperature of 1100°C had broad XRD peak at around 28°. One glass phosphor powder was formed from one droplet at the preparation temperature range from 900 to 1100°C. The mean size of the glass phosphor powders was 0.75 μm. The glass transition temperature (Tg) of the glass phosphor powders prepared by spray pyrolysis was 378.5°C. The excitation spectrum of the glass phosphor powders prepared at the optimum preparation temperature of 1100°C had bands at 362, 381, 392, 463, 525, and 532 nm. The glass phosphor powders had emission spectra with bands at 579, 614, and 653 nm. The glass phosphor powders with doping concentration of Eu of 7 wt% had the maximum photoluminescence intensity. The glass phosphor layer formed from the glass phosphor powders had high transparencies above 90%.

Dielectric properties of low temperature cofired BaO–Nd2O3–TiO2 ceramics

Glass ceramic materials were fabricated based on BaO–ZnO–B2O3 (BZB) glass with Ba6–3x(Nd1–yBiy)8+2xTi18O54 ceramics. It was investigated that the dielectric properties and the sintering behaviour of glass ceramics. Doped by BZB glass, the sintering temperature of Ba6–3x(Nd1–yBiy)8+2xTi18O54 ceramics was significantly lowered to 900°C in comparison to 1300°C for samples without glass. The low softening point BZB glass provided good wetting between BZB and Ba6–3x(Nd1–yBiy)8+2xTi18O54, and the reaction between glass and ceramics was increased. The dielectric constant of BZB-Ba6–3x(Nd1–yBiy)8+2xTi18O54 system was increased with increasing firing time. The composite sintered at 900°C for 2 h exhibited excellent dielectric properties were achieved, with dielectric constant of 75, the dielectric loss of 5 × 10–5 and the temperature coefficient of ±30 ppm °C–1.

Optical Properties of Co3O4-Doped ZnO–B2O3–SiO2–Al2O3Glass System for a Transparent Dielectric Layer

There has been a need to improve color temperature without using asymmetric cell structures using transparent dielectric layers with variation of Co3O4 contents in plasma display panel (PDP). In this study, ZnO–B2O3–SiO2–Al2O3 glasses with variations of the Co3O4 content (0, 0.5, 1.0, 1.5, and 2.0 wt%) were fabricated and the optical properties of these glasses were characterized. As the content of Co3O4 increased, the transmittance of the red region (from 580 to 780 nm) decreased more than of the blue region (from 380 to 500 nm). This change of transmittance induced the transition of the coordination of the color temperature toward the blue region. Therefore, the addition of 2 wt% Co3O4 can improve the color temperature from 6087 to 7378 K and the result was confirmed using simulation.

White light generation from Dy3+-doped ZnO–B2O3–P2O5 glasses

Dysprosium doped ZnO–B2O3–P2O5 (ZBP) glasses were prepared by a conventional melt quenching technique in order to study the luminescent properties and their utility for white light emitting diodes (LEDs). X-ray diffraction spectra revealed the amorphous nature of the glass sample. The present glasses were characterized by infrared and Raman spectra to evaluate the vibrational features of the samples. The emission and excitation spectra were reported for the ZBP glasses. Strong blue (484 nm) and yellow (574 nm) emission bands were observed upon various excitations. These two emissions correspond to the F49/2→H615/2 and F49/2→H613/2 transitions of Dy3+ ions, respectively. Combination of these blue and yellow bands gives white light to the naked eye. First time, it was found that ZnO–B2O3–P2O5 glasses efficiently emit white light under 400 and 454 nm excitations, which are nearly match with the emissions of commercial GaN blue LEDs and InGaN LED, respectively. CIE chromaticity coordinates also calculated for Dy3+: ZBP glasses to evaluate the white light emission.

Sensitized red luminescence from Bi3+ co-doped Eu3+: ZnO–B2O3 glasses

Photoluminescence properties of Bi3+ co-doped Eu3+ containing zinc borate glasses have been investigated and the results are reported here. Bright red emission due to a dominant electric dipole transition 5D0→7F2 of the Eu3+ ions has been observed from these glasses. The nature of Stark components from the measured fluorescence transitions of Eu3+ ions reveal that the rare earth ions could take the lattice sites of Cs or lower point symmetry in the zinc borate glass hosts. The significant enhancement of Eu3+ emission intensity by 346 nm excitation (1S0→3P1 of Bi3+ ions) elucidates the sensitization effect of co-dopant. The energy transfer mechanism between sensitizer (Bi3+) and activator (Eu3+) ions has been explained.

Microwave Dielectric Properties of Li2TiO3 Ceramics Doped with ZnO–B2O3 Frit

A type of new low sintering temperature ceramic, Li2TiO3 ceramic, has been found. Although it is difficult for the Li2TiO3 compound to be sintered compactly at temperatures above 1000°C for the volatilization of Li2O, dense Li2TiO3 ceramics were obtained by conventional solid‐state reaction method at the sintering temperature of 900°C with the addition of ZnO–B2O3 frit. The sintering behavior and microwave dielectric properties of Li2TiO3 ceramics with less ZnO–B2O3 frit (≤3.0 wt%) doping were investigated. The addition of ZnO–B2O3 frit can lower the sintering temperature of the Li2TiO3 ceramics, but it does not apparently degrade the microwave dielectric properties of the Li2TiO3 ceramics. Typically, the good microwave dielectric properties of ɛr=23.06, Q×f=32 275 GHz, τf=35.79 ppm/°C were obtained for 2.5 wt% ZnO–B2O3 frit‐doped Li2TiO3 ceramics sintered at 900°C for 2 h. The porosity was 0.08%. The Li2TiO3 ceramic system may be a promising candidate for low‐temperature cofired ceramics applications.

Photocatalytic degradation of Orange II by titania addition to sol–gel glasses

Glasses on SiO2–CaO–ZnO–B2O3–K2O–Al2O3 oxide system modified by addition of titania (0, 3, 5, 12, and 20% w) have been prepared by sol–gel method. The obtained gels were aged, dried and fired at 600 °C/1 h in order to stabilise the glass. The resulting fired powders were characterised by UV–Vis–NIR spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). Their photocatalytic capacity on the degradation of Orange II dye has been studied. The XRD and TEM studies indicate that system becomes amorphous with a nanostructured microstructure. From UV–Vis–NIR results the band gap calculated is around 3.5 eV for all modified glasses. Photoactivity of powders depends on amount of titania in glass composition and the specific surface area of prepared samples. The sample with highest surface area and lowest addition of titania (3% w sample) shows similar activity than commercial anatase used as reference.

Dielectric Constant and Optical Reflectance of Ceramic Filler‐Added BaO–ZnO–B2O3–P2O5 Glass Composites

This study examined the influence of the addition of ceramic fillers (up to 20 wt% of TiO2, Al2O3, and ZnO, respectively) to a BaO–ZnO–B2O3–P2O5 glass matrix on the dielectric and optical properties with the aim of using this material as the barrier ribs in plasma display panels. The modification of the dielectric constant by the fillers was related to the formation of secondary phases, the changes in the glass composition by the partial dissolution of the fillers, and the presence of pores. The reflectance of the composites ranged from 60% to 80% with the addition of 20 wt% filler.

Microwave Dielectric Properties and Low‐Temperature Sintering of Cerium Oxide for LTCC Applications

The effect of glass additives on the microstructure, densification, and microwave dielectric properties of cerium oxide for low‐temperature co‐fired applications was investigated. Different weight percentages of quenched glass such as B2O3, B2O3–SiO2, Al2O3–SiO2, ZnO–B2O3, BaO–B2O3–SiO2, MgO–B2O3–SiO2, PbO–B2O3–SiO2, ZnO–B2O3–SiO2, 2MgO–Al2O3–5SiO2, LiO–B2O3–SiO2, Bi2O3–ZnO–B2O3–SiO2, and LiO–MgO–ZnO–B2O3–SiO2 were added to CeO2 powder. The crystal structure of the ceramic–glass composites was studied by X‐ray diffraction, microstructure by scanning electron microscopy, and phase composition using the energy‐dispersive X‐ray analysis technique. The microwave dielectric properties such as relative permittivity (ɛr), quality factor (Quxf), and coefficient of temperature variation of resonant frequency (τf) of the ceramics have been measured in the frequency range 4–6 GHz. Addition of B2O3 and Bi2O3–ZnO–B2O3–SiO2 lowered the sintering temperature of ceria to about 900°C. The 20 wt% B2O3 and 10 wt% Bi2O3–ZnO–B2O3–SiO2‐added CeO2 and sintered at 900° and 950°C showed: Quxf=24 200 and 12 000 GHz, ɛr= 13.2 and 22.4, and τf=−46 and –57.2 ppm/°C, respectively.

Photoluminescence of Pr3+, Sm3+ and Dy3+: SiO2–Al2O3–LiF–GdF3 glass ceramics and Sm3+, Dy3+: GeO2–B2O3–ZnO–LaF3 glasses

In this paper, we present the absorption and photoluminescence properties of Pr 3+ , Sm 3+ and Dy 3+ -doped transparent oxyfluoride alumino-silicate glass ceramics and Sm 3+ and Dy 3+ -doped oxyfluoride germanate glasses. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of these glasses have been carried out, to confirm their structure and thermal stability. These glasses or glass ceramics have shown strong emission and absorption bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd–Ofelt (J–O) intensity parameters ( Ω 2 , Ω 4 and Ω 6 ) have been calculated for all the studied ions. Compared to Pr 3+ , Sm 3+ and Dy 3+ doped glasses, their respective glass ceramics have shown stronger emissions due to LiGdF 4 crystalline phase in alumino-silicate glass ceramics. For Pr 3+ doped glass and glass ceramic, emission bands centered at 527 nm( 3 P 0 → 3 H 5 ), 610 nm( 3 P 0 → 3 H 6 ), 640 nm( 3 P 0 → 3 F 2 ), 678 nm( 3 P 1 → 3 F 3 ), 702 nm( 3 P 0 → 3 F 3 ) and 721 nm( 3 P 0 → 3 F 4 ) have been observed with 445 nm( 3 H 4 → 3 P 2 ) excitation wavelength. Of them, 640 nm( 3 P 0 → 3 F 2 ) has shown bright red emission. Emission bands of 4 G 5/2 → 6 H 5/2 (562 nm), 4 G 5/2 → 6 H 7/2 (598 nm), 4 G 5/2 → 6 H 9/2 (644 nm) and 706 nm( 4 G 5/2 → 6 H 11/2 ) for the Sm 3+ : glass and glass ceramic, with excitation at 6 H 5/2 → 4 F 7/2 (402 nm) have been recorded. Of them, 4 G 5/2 → 6 H 7/2 (598 nm) has shown a bright orange emission. With regard to the Dy 3+ : glass and glass ceramic, a bright fluorescent yellow emission at 576 nm( 4 F 9/2 → 6 H 13/2 ) and blue emission at 485 nm( 4 F 9/2 → 6 H 15/2 ) have been observed, apart from 4 F 9/2 → 6 H 11/2 (662 nm) emission transition for glass ceramic with an excitation at 388 nm( 6 H 15/2 → 4 I 13/2 + 4 F 7/2 ) wavelength. For germanate glasses, emission bands of 4 G 5/2 → 6 H 5/2 (564 nm), 4 G 5/2 → 6 H 7/2 (601 nm), 4 G 5/2 → 6 H 9/2 (644 nm) and 705 nm( 4 G 5/2 → 6 H 11/2 ) for the Sm 3+ : glass, with an excitation at 6 H 5/2 → 4 F 7/2 (401 nm) have been recorded. Of them, 4 G 5/2 → 6 H 7/2 (601 nm) has shown a bright orange emission. With regard to the Dy 3+ : glass, a bright fluorescent yellow emission at 576 nm( 4 F 9/2 → 6 H 13/2 ) and blue emission at 482 nm( 4 F 9/2 → 6 H 15/2 ) have been observed, apart from 4 F 9/2 → 6 H 11/2 (661 nm) emission transition with an excitation at 386 nm( 6 H 15/2 → 4 I 13/2 + 4 F 7/2 ) wavelength. The stimulated emission cross-sections of all the emission bands of Pr 3+ , Sm 3+ and Dy 3+ : glasses and glass ceramics have been computed based on their measured full-width at half maxima (FWHM, Δ λ ) and measured lifetimes ( τ m ).

Low-Firing and Microwave Dielectric Properties of Ba2Ti9O20 with BaO–B2O3–ZnO Glass Addition

A low-firing ceramic material was fabricated by sintering a mixture of Ba2Ti9O20 with a BaO–B2O3–ZnO (BBZ) glass between 880 and 940 °C for 2 h, and the effects of BBZ glass additives on the sintering behavior and microwave dielectric properties were investigated. The results of this show that as the content of glass increased, the sintering temperature of material decreased. The material can be fully sintered at 900–920 °C with glass additives higher than 15 wt %. Two main crystalline phases, Ba2Ti9O20 and BaTi(BO3)2, were found in the ceramics, and the latter was formed by the reaction between Ba2Ti9O20 and the BBZ glass. The dielectric constant εr and the temperature coefficient of resonant frequency τf decreased and quality factor Q×f increased as the content of glass additive increased; ceramics containing 20 wt % BBZ glass additive sintered at 900 °C had εr=26.6, Q×f=11952 GHz, τf =-6.6 ppm/°C.

Low temperature sintering and dielectric properties of Ba2Ti3Nb4O18 ceramics for silver co-sintering application

Low temperature sintering and dielectric properties of Ba2Ti3Nb4O18 ceramics with ZnO–B2O3–SiO2 (ZBS) frit and lithium salts addition were investigated for silver co-sintering application. The sintering temperature of dense Ba2Ti3Nb4O18 ceramics with ZBS frit or LiNO3 addition was effectively lowered to 950 or 1,000 °C, respectively. LiNO3 is found to be more efficient than LiF or Li2CO3 to lower the sintering temperature of Ba2Ti3Nb4O18 ceramics. The sintering temperature of 900 °C was obtained for the Ba2Ti3Nb4O18 ceramics with a combination of ZBS frit and LiNO3 addition. The dielectric properties of Ba2Ti3Nb4O18 ceramics with 1 wt.% ZBS and 0.5 wt.% LiNO3 sintered at 900 °C are as follows: er ~ 37.8, tan δ ~ 0.0003, τe ~ 4.6 ppm/°C.

Spectral analysis of RE3+ (RE = Er, Nd, Prand Ho):GeO2–B2O3–ZnO–LiF glasses

This paper reports on the absorption, visible and near-infrared luminescence properties ofEr3+,Nd3+,Pr3+ and Ho3+-doped alkali fluoride zinc boro germanate glasses. The x-ray diffraction(XRD) and differential thermal analysis (DTA) profiles of the host glasshave been carried out, to confirm its structure and thermal stability. Fromthe measured absorption spectra, Judd–Ofelt (JO) intensity parameters(Ω2,Ω4 and Ω6) have been calculated for all the studied ions. ForPr3+ and Ho3+-doped glasses, upconversion emission spectra have also beenmeasured. Decay curves were measured for the visible emissions ofEr3+,Pr3+ andHo3+ ions at 547 nm(Er3+: green), 604 nm and641 nm (Pr3+: orange andred) and 658 nm (Ho3+: red), respectively. The near-infrared emission spectra ofEr3+/Yb3+ and Nd3+-doped glasses have shown full width at half maximum (FWHM) around 95 nm (for the transition) and 63 nm (for the transition), respectively. The measured maximum decay times of transition (at wavelength 1.51 µm) are about 5.72 ms and 6.14 ms for1.0Er3+ and 1.0Er3+/ 2Yb3+ (mol%)-codoped glasses, respectively. The maximum stimulated emission crosssections for transition of Er3+ and Er3+/Yb3+ are 5.447 × 10−21 cm2 and 4.540 × 10−21 cm2. These glasses with better thermal stability, bright visible emissions and broadnear-infrared emissions should have potential applications in broadly tunable laser sources,interesting optical luminescent materials and broadband optical amplification in low-losstelecommunication windows.

Thermophysical Properties of Ceramic Filler-Added BaO–ZnO–B2O3–P2O5 Glass Composites for Barrier Ribs of Plasma Display Panels

The capability of BaO–ZnO–B2O3–P2O5 glass in hosting various ceramic fillers (up to 20 mass% of Al2O3, TiO2, and ZnO) has been investigated. All the investigated filler-added glasses have demonstrated a reasonable densification at 550 °C to form stable ceramic filler-glass composites. Modifications of the thermophysical properties, such as coefficient of thermal expansion (CTE), glass transition temperature, and dilatometric softening temperature, by the addition of the fillers have been investigated and correlated to phase and microstructural evolution. The CTE of the fabricated composites with varying filler addition is well correlated with theoretical predictions based on the Turner equation considering the modification by phase evolution, which indicates the thermal property tuning potential of the BZBP-based glass composites for application to barrier ribs of plasma display panels.

Mechanical and acid-etching properties of Bi2O3–ZnO–B2O3 glass-containing ceramic fillers

The properties of the composite, having a complicated microstructure, are decided by many factors such as those of glass matrix, crystal phases, fillers, and holes. We investigated how the addition of ceramic fillers to the glass matrix affects the mechanical and etching properties of the glass composite by forming new crystal phases. Different amounts of two fillers, ZnO and Al2O3, were added to a glass frit consisting of Bi2O3–ZnO–B2O3. It was sintered at 550 °C for 30 min. Based on the results of this study, the porosity and degree of crystallization of the composites could be controlled by adjusting the content of the ZnO and Al2O3 fillers. Therefore, porosity and degree of crystallization formed by the reaction between a glass matrix and fillers influence the mechanical and etching properties of the composite.