Mother Glass Research Articles

Crystallization temperature dependence of structure, electrical and energy storage properties in BaO–Na2O–Nb2O5–Al2O3–B2O3 glass ceramics

For dielectric capacitors, high energy density and discharge power density are crucial for utilisation in pulsed power devices. In this paper, BaO–Na2O–Nb2O5–Al2O3–B2O3 (BNN-AB) glass ceramics were successfully fabricated by melt quenching and heat treatment techniques. With increasing crystallization temperature, both the dielectric permittivity and breakdown strength (BDS) first increased and then decreased. When the crystallization temperature was lower than 800 °C, the principal crystalline phase was Ba2NaNb5O15 and the secondary phase was NaNbO3. When crystallization temperature was increased from 800 °C to 830 °C, a small amount of a third phase (Al4B2O9) appeared. At the crystallization temperature of 770 °C, the compact glass ceramics with a fine grain structure had the highest permittivity (∼216 @ 25 °C) and high BDS (∼1170 kV/cm). A single-layer capacitor made of glass ceramics had a high power density (∼414 MW/cm3) and discharge energy density (∼1.93 J/cm3), measured by the charge-discharge test platform under the applied field strength of 500 kV/cm. The discharge energy density of glass ceramics sample was as much as 7.7 times that of the mother glass. The above evidences indicate that BNN-AB glass ceramic materials have broad application prospects in the field of dielectric energy storage.

Crystallization-temperature controlled alkali-free niobate glass-ceramics with high energy storage density and actual discharge energy density

The niobate-based alkali-free ferroelectric glass-ceramics were realized through the synthesis of mother glass by way of melt-annealing technique, followed by temperature-controlled crystallization. As the crystallization temperature raised, the ratio of the ferroelectric crystal phase precipitated in the mother glass enhanced continuously, resulting in the enlargement of the permittivity. Attribute to the rise of grain size, pores and cracks tend to appear in the microstructure of glass-ceramics with high crystallization temperature, leading to lower breakdown strength. The theoretical simulation was applied to reveal the internal mechanism, exploring the outcome of heat treatment temperature on the breakdown electric field. The maximum theoretical energy storage density reaches to 18.44 J/cm3 at the crystallization temperature of 800 °C. The single-layer capacitor made from the G800 sample exhibited extremely high power density (230 MW/cm3) and superior actual discharge energy density (1.5 J/cm3) at 600 kV/cm. These results indicate that alkali-free niobate-based glass-ceramics is a kind of encouraging candidate material for pulse capacitors.

Influences of crystallization temperature on the structure, dielectric, and energy storage characteristics of KBaSrNb5O15‐based glass–ceramics

AbstractGlass–ceramics capacitors have great application potential in pulsed power systems, due to ultrafast discharge speed and high dielectric breakdown strength (BDS). Here, lead‐free niobate glass–ceramic dielectric materials were synthesized, and the effects of heat treatment temperature on the dielectric, ferroelectric, and energy storage properties of glass–ceramics were investigated comprehensively. The results exhibit that the dielectric permittivity first increases and then decreases as the crystallinity increases; however, the dielectric BDS diminishes. At the optimum crystallization temperature of 740°C, the maximum value of discharge energy density is 2.2 J/cm3 at 600 kV/cm, which is about 7.6 times that of mother glass. Furthermore, an ultrahigh power density of about 380.9 MW/cm3 and ultrafast discharge speed of about 11.2 ns were achieved simultaneously. Meanwhile, great thermal stability of charge–discharge property was verified in this glass–ceramics. According to P–E loops and dielectric test result, a high dielectric constant (∼207) and low dielectric loss (<0.005) as well as high energy storage efficiency of about 94.9% were achieved for G740 sample. The previous results make the obtained glass–ceramic as potential candidates in dielectric capacitors.

Processing and Evaluation of a Carbon Fiber Reinforced Composite Bar Using a Closed Impregnation Pultrusion System with Improved Production Speed

In this paper, an epoxy resin-based carbon fiber reinforced composite (CFRP) bar pultrusion system using a closed impregnation device which has various advantages in process compared to traditional open bath type pultrusion system was developed, and the fiber impregnation system was improved through the analysis of resin properties for the high-speed production of CFRP bars used to support the mother glass in the display transfer cassettes. To improve the fiber feeder system, fiber guides were switched from perforated plates to roller guides for spreading fibers, which allowed the input fibers to be widened and flattened while reducing the fiber thickness. Additionally, the correlation between resin viscosity and impregnation speed were analyzed to evaluate the resulting mechanical properties at different pultrusion speeds and temperatures. A CFRP bar was produced with resin injection at room temperature and a pultrusion rate of 400 mm/min and compared to a CFRP bar produced with fiber spreading, a resin injection temperature of 40 °C, and a pultrusion rate of 600 mm/min; the latter with a 50% improved production rate showed improvements in mechanical properties, including the cross-sectional void by 98.7%, surface roughness by 75.5%, deflection by 34.9%, and bending strength by 70%.

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A Forgivable Enthusiasm

Wide thermal expansion in Ag0/Au0 nanoparticle doped SiO2-MgO-Al2O3-B2O3-K2O-MgF2 glass-ceramics

This report demonstrates high temperature sealing tendency of alumino-silicate glasses (ASG) on the system SiO2-MgO-Al2O3-B2O3-K2O-MgF2 doped with silver (Ag) and gold (Au) nanoparticles. Density of the melt-quenched (1550 °C) glasses were in 2.51–2.55 g.cm−3. The glasses were heat-treated at 900 ± 10 °C over which the opaque glass-ceramics were obtained with major crystalline phase (XRD) fluorophlogopite mica [KMg3(AlSi3O10)F2] with secondary phase norbergite (Mg2SiO4.MgF2). FESEM study indicated the development of Rod-like and rock-like crystallite particles (size ∼1–4 µm) randomly dispersed in mother glass–ceramic which was restructured into nanocrystalline morphology (crystallite size ∼100–400 nm) with the aid of Ag- or Au- nanoparticles. The significant change in microstructure influenced the corresponding density (2.51–2.55 g.cm−3) and thermal expansion characteristics. Coefficient of thermal expansion (CTE) for ASG was estimated to be 9.96 ± 0.10×10−6/K (50–800 °C), which increased to 10.46–11.01×10−6/K when doped with Ag- or Au- content. Such wide CTE (11.01 ± 0.11×10−6/K) value matches well with the CTE of ceramic/metallic materials used for high temperature application thus Ag- doped SiO2-MgO-Al2O3-B2O3-K2O-MgF2 glass can be a suitable for high temperature sealing application (like SOFC).

P‐43: Correlation Between LC Bubbles and Product Design

LC bubble issue in corners happens easily in super‐narrow‐border LCD products. This paper studied the relationship of LC bubble issue with LCD panel design, which includes LC drop pattern, flatten layer material and panel chip layout design in mother glass. Also tried to analysis the basic factors which can be used to improve the bubble issue.

Preparation and characterization of hexagonal Li4GeO4-based glass-ceramic electrolytes

A new lithium-ion conducting oxide, hexagonal Li4GeO4, with a space group of P63/mmc, was prepared by mechanochemical treatment and subsequent heat treatment at 250 °C. The crystal structure was found in sulfide Li4SnS4, and this is the first study to report an oxide system. In addition, (100-x)Li4GeO4·xLi2MO4 (M = S or W; x = 10, 20, 30, and 40 mol%) glass-ceramic electrolytes with the hexagonal phase were prepared by crystallization of their mother glasses. The formability of the electrolytes improved as the quantity of Li2SO4 increased, and the 90Li4GeO4·10Li2SO4 glass-ceramic electrolyte showed the highest ionic conductivity of 2.9 × 10−6 S cm−1 at 25 °C. Compared with the experimental results, the bond valence sum (BVS) analysis results indicated that ionic conduction paths are easily connected along the c-axis in the hexagonal phase, suggesting that the relatively small lattices in the a- and b-axes are more advantageous for three-dimensional ionic conduction.

Structure-property correlations in lithium zinc cobalt metaphosphate glasses and glass-ceramics

The main goal of this work is to study the physical, structural, optical, and electrical properties of alkali zinc phosphate glasses doped with CoO oxide with the general formula 10Li2O-xCoO-(40-x)ZnO–50P2O5. Using the standard melt-quench technique, a large glass-forming region is obtained, and up to 40 mol% CoO doped glasses are prepared. XRD diffraction confirmed the amorphous nature of these materials. Density, molar volume, and the glass transition temperature (Tg) are composition-dependent. Infrared (IR) spectroscopy is performed to study the structural approach. It is observed that the substitution of ZnO by CoO oxide in the glassy framework induces some structural modifications. The UV–Visible spectra of the CoO-doped glasses show visible absorption bands in the region 400–700 nm which are related to the coexistence of cobalt in divalent and trivalent states. The crystallization behaviour of the samples is performed by submitting the glasses to controlled heat treatments and the crystalline phases obtained are identified by X-Ray diffraction (XRD). The kinetic of the crystallization is carried out by employing the thermal analysis (DSC) technique. The crystallization process is discussed regarding the obtained activation energy (Ec) and Avrami parameter (n). The Vickers hardness values of the glasses and the glass-ceramics are determined and discussed according to the bond strengths. The electrical conductivity of these materials is investigated over a large frequency domain at various temperatures. It is found that the electric conductivity decreases with increasing cobalt content. It is also noted that the conductivity of each glass-ceramic is reduced in comparison with that of its mother glass. The frequency-dependent of the conductivity follows Jonscher's power law and the correlated barrier hopping mechanisms (CBH) was appropriate for the conduction process inside the glasses. The electrical modulus formalism is applied to the electric data in order to study their dielectric relaxation. The results show that this latter is non-Debye type in agreement with the well-known universal responses of amorphous materials.

Crystallization Mechanism and Photoluminescence Properties of CaF₂-Al₂O₃-SiO₂: Eu Glass-Ceramics Based on Nano-Scale Phase Separation Phenomenon.

In this paper, CaF₂-Al₂O₃-SiO₂ glass containing nano-sized CaF2 crystals were fabricated using phase separation phenomenon and the effects of rare earth ion (Eu) addition on the optical properties were investigated. The formation conditions for nano-sized CaF₂ crystal phase were confirmed using non-isothermal analysis and X-ray diffraction (XRD) measurement, while inhibiting anorthite or wollastonite crystal formation. The phase separation phenomenon in the mother glass and the nano-sized crystals generated by heat treatment were observed through the microstructure analysis using scanning electron microscopy (SEM). In addition, photoluminescence (PL) spectra and decay time analysis were performed to confirm the emission characteristics of Eu-doped glass-ceramics. The Eu-doped glass-ceramics produced in this study showed strong red light. The overall luminescence properties according to the heat treatment temperatures were found to shift from red to blue as indicated in the Commission International de l'Eclairage (CIE) color coordinate system.

Zr+4-controlled nucleation and microstructure in Si-Mg-Al-K-B-F glass-ceramic sealant (solid oxide fuel cell)

This work illustrates the strong effects of Ti4+ and Zr4+ (M4+) on nucleation ability of SiO2-MgO-Al2O3-B2O3-K2O-F glass-ceramic sealant. An addition of such 5 wt.% M4+ content caused a slight increase in density value (2.60–2.61 g.cm−3). X-ray diffraction (XRD) experiment revealed no indication of any crystallinity in melt-quenched glass-sealant and that was further confirmed from transmission electron microscopy. XRD established the development of multicrystalline phases in investigated glass-sealants at solid oxide fuel cell (SOFC) operation temperature (=800 °C). The reflected XRD peaks on the heat-treated (i.e., 800 °C) SiO2-MgO-Al2O3-B2O3-K2O-F glasses were indexed as norbergite (Mg2SiO4.MgF2), humite [Mg7F2(SiO4)3], chondrodite [Mg5F2(SiO4)2], mullite (3Al2O3·2SiO2) and enstatite (MgSiO3) phases. Field-emission scanning electron microscope (FESEM) experiment indicated that the plate-like crystallite particles (size 3–10 μm) were precipitated in a mother glass matrix heated at 800 °C and restructured into droplet-type morphology when nucleation was supported by Ti4+ ions. The presence of Zr4+ ion results an interlocked type microstructure that is desirable for sealing application because of their capability to resist the growth of a microcrack caused due to thermal stress. A wide thermal expansion value (=11.06 × 10−6/K) compatible with SOFC components (electrode, electrolyte, interconnect, and so on) is achieved for Zr4+-doped SiO2-MgO-Al2O3-B2O3-K2O-F glass-ceramic. No considerable deformation in thermal expansion value up to 10 thermal cycling operations is obtained for Zr4+ doped glass and this is ascribed to the interlocked type morphology (FESEM).

Exploration of zinc borophosphate glasses as dispersion media for SiAlON phosphors

AbstractCa‐α‐SiAlON:Eu2+ oxynitride phosphors are typical luminescent materials with high thermal tolerances. A series of zinc borophosphate glass samples (ZnO–B2O3–P2O5) were prepared to investigate their ability to disperse Ca‐α‐SiAlON:Eu2+ phosphor powders and to obtain phosphor‐in‐glass (PiG). PiG was prepared with SiAlON and zinc borophosphate glass through a melting process, and seven types of PiGs were successfully obtained without obvious degradation of SiAlON. In particular, PiGs prepared from 30ZnO–40B2O3–30P2O5 and 60ZnO–30B2O3–10P2O5 (mol%) glasses showed the highest quantum efficiency (QE). The glass structures of the mother glasses were investigated by nuclear magnetic resonance spectroscopy (NMR) and Raman spectroscopy; it was important to reduce the Q0 species of PO4 units and 4‐coordinate boron for a high QE. From the X‐ray diffraction (XRD) and scanning electron microscopy (SEM) images, it was established that ZnAl2O4 was formed around the SiAlON powders in PiG composed of the 60ZnO–30B2O3–10P2O5 (mol%) glass.

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Development of sulfide solid electrolytes prepared by crystallization of mother glasses

Development of sulfide solid electrolytes prepared by crystallization of mother glasses

Structure Studies of BaO-TiO2-SiO2 Glass-Ceramics Using 29Si MAS NMR and Raman Spectroscopy

Abstract The structural correlation between the BaO-TiO2-SiO2 (BTS) glass and the corresponding (BTS) glass-ceramic is examined by 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) analysis along with Raman spectroscopy and X-ray diffraction (XRD) measurements. From the deconvoluted spectrum of each Si unit, denoted by Qn, in both the BTS glasses and the BTS glass-ceramics, it is found that structural rearrangement of Si occurs from the Q2 and Q3 units to Ba2TiSi2O8 and the residual amorphous region, respectively. These results of 29Si MAS NMR analysis and Raman spectroscopy, together with XRD measurements, show that the local structure of the BTS mother glass reflects that of the corresponding crystals. This finding is expected to be valuable for tailoring the structure of functional glass-ceramics.

Optical properties of zinc borate glasses dispersed with Eu-doped SiAlON for white LED applications

Ca-α-SiAlON:Eu2+ oxynitride phosphors are typical luminescent materials with high thermal tolerances. A series of zinc borate glass samples (xZnO-(100-x)B2O3; mol%) were prepared for investigating their ability to disperse Ca-α-SiAlON:Eu2+ phosphor powders. Phosphor in glass (PiG) was prepared with SiAlON and zinc borate glass through a melting process. In the x = 45–60 range, PiGs could be obtained without the degradation of the SiAlON phosphors. The PiG composed of x = 50 glass exhibited the highest quantum efficiency. The glass structures of the mother glasses were investigated by Raman spectra; there was a decrease in the boroxol ring, and pyroborate and orthoborate were formed, on increasing x. From the XRD and SEM images, it was established that ZnAl2O4 was formed around the SiAlON powders in PiGs with x = 50, 55, and 60, respectively. This suggests that the partial crystallizations in the PiGs are effective in enhancing the photoluminescence of the SiAlON phosphors.

Coloration Mechanism of Fe Ions in β-Quartz s.s. Glass-Ceramics with TiO2 and ZrO2 as Nucleation Agents

Transparent Li2O-Al2O3-SiO2 low-expansion glass-ceramics have an undesirable brown color owing to Fe ions as a contaminant, whereas the mother glass normally has a clear appearance. Elucidation of the coloration mechanism during crystallization is important for industry to develop highly transparent materials. In this study, the mother glass contained SiO2, Al2O3, and Li2O as its principal constituents and TiO2 and ZrO2 as nucleation agents. The amount of contaminant Fe ions in the form of Fe2O3 was 0.03 wt%. It was confirmed that the coloration was appeared by the coexistence of Fe and Ti ions in the glass matrix based on the experimental results using Ti-containing and Ti-free glasses with a composition identical to that of the glass matrix. The coordination and oxidation state of the Fe ions were not changed by the coexistence of Ti ion according to the results of XANES measurement. The coloration is considered to be due to the formation of Fe-O-Ti by the concentration of Fe and Ti ions in the glass matrix phase during the crystallization process.

Effect of Processing Conditions of 75Li2S-25P2S5 Solid Electrolyte on its DC Electrochemical Behavior

The effect of processing conditions of the 75Li2S-25P2S5 (LPS) on the Li/LPS DC electrochemical stability was investigated. LPS was densified by compacting at room temperature, and hot pressed between 130–300°C, 47MPa. The relative density (80% for all samples) was not affected by the hot pressing temperature, which was likely due to insufficient bulk diffusion (at the pressure used within the temperature range selected) to promote densification. The highly conductive meta-stable crystalline phase (thio-LiSICON III analog) precipitated from the mother glass when hot pressing between 170 − 250°C and the low conductivity Li3PS4 phase formed when hot pressing at 300°C. The Li/LPS DC electrochemical stability was characterized as a function of current density between 0.01–1.0mAcm−2. Two phenomena were observed; first, as the current density increased, deviation from Ohmic behavior was observed, manifested in an increase in output potential difference. Second, as the current density was further increased, a drop in cell potential was observed followed by an output potential difference instability; likely consistent with short-circuiting caused by Li metal propagation. The highest critical current density, at which short circuit occurs, resulted when hot pressing at 170°C, reaching 1.0mAcm−2. In general, obtaining LPS glass-ceramic through hot pressing increased the rate at which current can be passed through the cell. It is believed that further atomic/microstructure optimization can improve the critical current density of LPS.

Minimizing loss in LCD glass manufacturing by cutting pattern optimization based on integer programming

Loss reduction plays a critical role in improving both process efficiency and overall profitability. As processes become more complex, loss reduction becomes more challenging and systematic decision-supporting methods are thus needed. This paper illustrates such a method in the context of liquid crystal display (LCD) glass production, which involves a series of chemical processes. Loss-minimizing integer programming models are proposed to compute a cutting pattern that allocates multiple demands to LCD mother glass. Numerical examples from actual LCD glass processes are presented to illustrate the applicability of the proposed method.

Preparation of hybrids derived from zinc phosphate glasses and benzimidazole for anhydrous proton conduction applications

Anhydrous proton-conducting hybrid materials have been prepared using zinc metaphosphate glass and benzimidazole. In the present work, the glasses containing hydrated crystals, as the starting material, were used for preparing the hybrids to examine the influence of the hybrid structure on their electrical conductivities. The glass powders were exposed to humidified conditions and subsequently heated at 150 °C to form crystal phases in the glasses; the treated powders included large amounts of ortho- and pyrophosphate groups. Proton-conducting hybrids were successfully prepared by programmed-heating the mixtures consisting of the treated powders and benzimidazole to 220 °C. The resulting hybrids were amorphous and thermally stable up to 200 °C. One of the hybrids prepared using the treated powders containing large amounts of hydrated crystals showed higher conductivities than that prepared using the mother glass. The humidifying-heating process of the metaphosphate glass powders, prior to hybridization with benzimidazole, plays an important role in an increase in orthophosphate groups in the resulting hybrids, leading to improvement of their electrical conductivities.