Low Melting Temperature Glass Research Articles

Functionalization of Phosphate and Tellurite Glasses and Spherical Whispering Gallery Mode Microresonators.

Active whispering gallery mode resonators made as spherical microspheres doped with quantum dots or rare earth ions achieve high quality factors and are excellent candidates for biosensors capable of detecting biomolecules at low concentrations. However, to produce quantum dot-doped microspheres, new low melting temperature glasses are sought, which require surface functionalization and antibody immobilization for biosensor development. Here, we demonstrate the successful functionalization of three low melting point glasses and microspheres made of them. The glasses were made from sodium borophosphate, sodium aluminophosphate, and tellurite, and then, they were functionalized using (3-glycidyloxypropyl)trimethoxysilane in ethanol- and toluene-based protocols. Proper silanization was confirmed by energy-dispersive X-ray spectroscopy and fluorescence microscopy of an amino-modified luminescent oligonucleotide probe. Fluorescence imaging showed successful silanization for all tested samples and no degradation for aluminophosphate and tellurite glasses. The strongest signal was registered for tellurite glass samples functionalized using the toluene-based silanization protocol. This conclusion implies that this functionalization method is the most efficient and is highly recommended for future antibody immobilization and biosensing application.

Characterization of medium chain length polyhydroxyalkanoates from Priestia megaterium POD1

Polyhydroxyalkanoate (PHA) is the most promising solution to the major ecological problem of plastic accumulation. It is synthesized by bacteria when there is limited availability of nutrients as intracellular granules. The biodegradable and biocompatible properties of PHA make it highly demanding in the biomedical and agricultural field. Among PHA, medium chain length (mcl) PHA has shown more interest because of its favorable properties like having more viscous material, low crystallinity degrees, low melting temperature and low glass transition temperatures for many applications which require flexible material. Therefore, we have isolated a bacterial strain, Priestia megaterium POD1 which can produce mcl PHA very efficiently. The isolate was confirmed to have phaC gene responsible for PHA synthesis. The PHA extracted from the isolate was characterized by FTIR, NMR and GC-MS which revealed the extracted polymer to be a mixture of different mcl PHA. Hence, the present study would provide a potential mcl PHA producer which can be explored for its properties which are demanding in present bioplastic market.

A Study on Ceramic Heater Devices Based on Si3N4 with a MoO3 Protective Layer

Currently, the need for high performance heaters for industrial application is increasing, and repeated wear, rapid temperature change, and uneven temperature can cause deteriorating quality and reduced productivity. The ceramic heater in this study consists of a substrate, an electrode layer, and a protective layer, and low-melting temperature glass frit was used for all layers to allow low-temperature processing. As a substrate for the ceramic heater, Si3N4, which is twice as strong as AlN and has excellent wear resistance, was used. As the electrode material, Ag-Pd, which provides good adhesion to the Si3N4 substrate and high electrical conductivity was used, and MoO3 powder was mixed 8 : 2 to make a paste. The MoO3 adjusts the resistance of the Ag-Pd electrode, thereby supplementing the heater performance. Si3N4 powder and glass frit were used for the protective film layer that protects the electrode, and MoO3 was added to unify the materials between the layers.

Tunable white light in trivalent europium single doped tin fluorophosphates ultra-low melting glass

In recent years, low melting temperature glasses have received wide attention as the hosts of phosphor-converted light emitting diodes (pc-WLED). In this work, a series of trivalent europium doped tin fluorophosphates glasses were prepared by conventional melting method. Under ultraviolet excitation, the blue-green broadband emission from Sn2+ activation centers in the glass matrix and the red emission of Eu3+ ions together constituted a cool white luminescence. The spectra analysis was used to demonstrate the energy transfer between Sn2+ centers and Eu3+ ions. The results showed that Sn2+ and Eu3+ possessed independent intrinsic emission and mutual energy transfer simultaneously. The 5D4 and 5G2 excited states of Eu3+ ion favored the energy transfer to Sn2+ center, the 5L6 excited state of Eu3+ ion would absorb more of the energy by the Sn2+ ground state excitation to contribute on red emission. Therefore, the fluorescent glass can transform cool white light to warm white light by changing the excitation wavelength. The tunable white light is obtained in the WLED devices built with the glass and commercial UV chips.

Laser sealing of organic light-emitting diode using low melting temperature glass frit

Glass frit encapsulation for laser-base sealing of the complex interiors results challenges for the electronics manufacturing process. The conventional frit packaging method relies on elevating thermal process by furnace where the package is heated to required temperature, hence limiting the use of temperature-sensitive materials and also creating problems in different packaging processes or multi-stage sealing products. In this paper, the benefits of combining novel laser-assist hermetical sealing and low temperature glass frit packaging are demonstrated and the technique offers a suitable and feasible solution. This frit of absorbent at specific laser wavelength is selected and applied as excellent contact with both large CTE range substrates. Glass frit composites consisting of a PbTiO3 ceramic and the rare earth Nd2O3 are evaluated for thermal properties and electrical characteristics. This developed glass frit hermetical sealing method achieves moisture durability, satisfying the enculturation of electronics-level. In this paper, we demonstrate successfully using laser to seal organic light emitting diode (OLED) via low melting temperature glass frit.

Coercivity of the Nd–Fe–B hot-deformed magnets diffusion-processed with low melting temperature glass forming alloys

Nd- and Pr-based alloys with bulk glass forming ability and low melting temperatures, Nd60Al10Ni10Cu20 and Pr60Al10Ni10Cu20, were used for grain boundary diffusion process to enhance the coercivity of hot-deformed magnets. The coercivity increment was proportional to the weight gain after the diffusion process. For the sample with 64% weight gain, the coercivity increased up to 2.8T, which is the highest value for bulk Nd–Fe–B magnets that do not contain heavy rare-earth elements, Dy or Tb. Approximately half of the intergranular regions were amorphous and the remaining regions were crystalline. Magnetic isolation of the Nd2Fe14B grains by the Nd-rich amorphous/crystalline intergranular phases is attributed to the large coercivity enhancement. The coercivity does not change after the crystallization of the intergranular phase, indicating that the coercivity is not influenced by the strain at the interface with the crystalline intergranular phase.

Nonisothermal and Isothermal Degradation Kinetics of Thermotropic Liquid Crystal Copolyesters Containing BPA and BPAF Units

The thermotropic liquid crystal copolyester P-BPA2.5 and P-BPAF2.5 with low melting temperature and high glass transition temperature were obtained by introducing 2.5mol% bisphenol A (BPA), bisphenol AF (BPAF) and terephthalic acid (TA) receptively into the molecular chain of poly (oxybenzoate-co-oxynaphthoate). The isothermal and nonisothermal degradation behavior of the two copolyesters P-BPA2.5 and P-BPAF2.5 were studied by thermo-gravimetry analysis (TGA) under nitrogen atmosphere. The degradation kinetics of the copolyesters under dynamic and isothermal heating conditions was evaluated byKissinger-Akahira-Sunose (KAS) and iso-conversional methodrespectively. Results showed that the activation energy (E) values followed the order P-BPAF2.5>P-BPA2.5 under dynamic heating atmosphere. However, the P-BPA2.5 showed a better thermal stability as compared with P-BPAF2.5 under isothermal heating conditions. The differences of degradation mechanism between the two copolyesters may be a reason for this phenomenon, which was discussed in detail in the text.

Ultra-high tunability in polycrystalline Ba1−xSrxTiO3 thin films

Ba0.7Sr0.3TiO3 thin polycrystalline films with an ultra-high capacitance tunability approaching 5:1 at 175 kV/cm were made possible by a flux-assisted synthesis approach. In this process, a small volume fraction of a low melting temperature glass is added during low-temperature sputter deposition. Subsequent annealing activates the liquid phase, which in turn provides the mass transport needed to approach full density, to increase grain size, and to improve crystallinity, and, in so doing, achieves a stronger non-linear dielectric response. Ba0.7Sr0.3TiO3 films with 0%, 1%, 4%, and 7% BaO-3B2O3 flux exhibited grain sizes of 25 nm, 28 nm, 48 nm, and 56 nm, and dielectric tunabilities of 25%, 33%, 64%, and 80% respectively. These values represent substantial improvements when compared to conventionally processed tunable dielectric films.

Nonisothermal and isothermal oxidative degradation behavior of thermotropic liquid crystal polyesters containing kinked bisphenol AF and bisphenol A units

The polyester P–bisphenol AF 2.5 (BPAF 2.5) and P-bisphenol A 2.5 (BPA 2.5) with low melting temperature and high glass transition temperature can be obtained by introducing 2.5 mol% BPAF/BPA and terephthalic acid (TA) units respectively into the molecular chain of poly(oxybenzoate- co-oxynaphthoate) (P-HBA70). In this study, the nonisothermal and isothermal oxidative degradation behavior of polyester P-BPA2.5 and P-BPAF2.5 were investigated comparatively with parent polyester P-HBA70 by thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy measurements. The introduction of BPAF/BPA units into the molecular chain of P-HBA70 strongly influenced the degradation behavior of polyesters. Four multiple heating rate methods including Kissinger, Kim–Park, Flynn–Wall–Ozawa, and Friedman methods were applied to evaluate the dynamic thermal stability successfully. The following order of the activation energy values: P-BPAF2.5 > P-HBA70 > P-BPA2.5 can be found for the three samples. However, from the results obtained by the standard isoconversional method, the P-BPA2.5 showed a better thermal stability as compared to P-BPAF2.5 under isothermal atmosphere.

Melt Compounding and Mechanical Properties of Polyphenylene Sulfide/Low Melting-temperature Glass Composites

Polyphenylene sulfide( PPS) with the melt temperature about 280 ℃ and low-melting temperature glasses( LMTG) with the soft-temperature( T s) about 325 ℃ were used to prepare PPS/LMTG organicinorganic hybrids by melt compounding above both characteristic temperatures. The surfaces of PPS / LMTG prepared at different processing conditions were observed by scanning electron microscope( SEM).Meanwhile,the mechanical properties for the composites marked as PPS / LMTG300 and PPS / LMTG400prepared below and above T s of LMTG respectively were investigated. The results indicate that liquid-liquid melt compounding is feasible in a wide temperature range from 325 ℃ to 450 ℃ for the selected composites.The SEM images show that dispersed phase in situ morphologies are influenced significantly by processing temperature,shear time and the mixer rotation speed. During liquid-liquid compounding,the dispersed phase,i. e. LMTG drops,goes through a series of process of deformation,break-up,coalescence and recovery in shearing field,similar to the evolution of dispersed polymer phase in immiscible blends with sea-island structure. Compared with PPS / LMTG300,the size of in situ morphology for LMTG phase in PPS / LMTG400obtained by liquid-liquid melt compounding is much smaller,leading to weaker interfacial interaction between the filler and matrix. In addition,LMTG particles still have an excellent strengthening effect on PPS /LMTG400 containing 66 wt% inorganic filler since particle dispersion is improved by liquid-liquid compounding.

I-129 Waste form Using Bi-Zn-P-Oxide Glass

I-129 is a problematic nuclide generated from the recycling of spent fuel by pyroprocess. Gaseous form of radiogenic iodine is trapped by using silver exchanged zeolite (AgX) at Korea Atomic Energy Research Institute (KAERI). We developed the low melting temperature glass system based on Bi2O3-P2O5 composition. Various additives were added to modify glass properties. We found that ingots containing AgI are formed with ZnO, CaCO3, MgO, and Na2CO3 at around 600°C. Analysis of microstructure and chemical durability revealed that AgI was encapsulated by glass matrix and formation of AgI compound is meaningful in fabricating iodine waste form.

The morphology and dynamic viscoelasticity for PPS/low-melting temperature glass hybrids prepared by melt blending

Abstract Polyphenylene sulfides (PPS) and low-melting temperature glasses (LMTG) were used to prepare a PPS/LMTG organic–inorganic hybrid material by melt blending. The etched surfaces of the hybrids were observed by scanning electron microscope (SEM) and the images showed different dispersed phase morphologies compared to traditional filled composites, which maybe induced by shear. Advanced rheometric expanded system (ARES) was used to investigate the rheological behaviors of the hybrids and the results showed that the strain γ dependence of dynamic storage modulus G′ for the hybrids with high contents of LMTG did not appear Payne effect.

Preparation of low melting temperature glass–ceramics from municipal waste incineration fly ash

Glass–ceramics have been prepared from air pollution control residues (fly ash) of a municipal solid waste incineration (MSWI) plant in southern China. The use of additives was investigated in order to decrease the melting temperature of the waste and thus to reduce the costs of production of glass–ceramics from the vitrified waste. Results showed that the melting temperature can be decreased significantly from 1500 to 1200 °C, which was achieved by combining the MSWI fly ash with silica sand powder and a Fe 2O 3-rich and CaO-rich iron slag to form a glass in the SiO 2–CaO–Al 2O 3–Fe 2O 3 quaternary phase system. Sodium carbonate and borax were used as fluxing agents and TiO 2 of chemical grade was added as a nucleation agent. The main crystalline phase in both high and low melting temperature glass–ceramics was found to be diopside (Fe-bearing), and the microstructure exhibited the presence of fine crystals of size in the range 100–200 nm which developed at crystallization temperatures in the range 800–900 °C for 1–2 h. The leaching behaviour of the glass–ceramic materials was tested, and it was found to be lower than that of a cement-stabilized body that was fabricated using the same waste for comparison. The results demonstrate the feasibility of reusing MSWI fly ash for glass–ceramic production at relatively low melting temperature, e.g. in a less energy-intensive process, as a viable approach for tackling the problem of hazardous MSWI residues.

The development of growth rings on ancient glass surfaces: Description and simulation of the weathering

The present work investigates the weathering process of glass surfaces with the formation of corrosion growth rings investigated by X-ray photoelectron spectroscopy, optical microscope, environmental scanning electron microscope and particle induced X-ray emission. The analysed samples are both ancient and recent glasses. The first set of samples is constituted by Roman glass fragments originally belonging to the load of the Iulia Felix ship, sunken in the Northern Adriatic sea (Grado, Italy) during II century AD. The samples were already investigated in the past [F. Barbana, R. Bertoncello, L. Milanese, C. Sada, J. Non-Cryst. Solids 337 (2) (2004) 136; B. Dal Bianco, R. Bertoncello, L. Milanese, S. Barison, J. Non-Cryst. Solids 343 (2004) 91; B. Dal Bianco, R. Bertoncello, L. Milanese, S. Barison, Surface Eng. 21 (5–6) (2005) 393; B. Dal Bianco, R. Bertoncello, L. Milanese, S. Barison, Archaeometry 47 (2) (2005) 353], but their production process is still unknown. The second set of samples belongs to the stained window of S. Giovanni church in Polegge (Vicenza, Italy) and it is dated to 1930 ca. The glass production process is well known. In fact, every tessera is made of soda-lime glass. On one side only, the glass is coated with a green pigment (low melting temperature glass) and then heated in oven in order to fix it on the glass. The window is then mounted and fixed to the wall. Unfortunately, during this procedure, the window was positioned inside-out, so that the painted surface was exposed to the direct action of the atmospheric conditions. This anomaly favoured the fast degradation of the tessera, with the presence of concentric rings at the surface. Another set of samples was produced in order to simulate the effects of moisture at the glass surface, using an industrial soda-lime glass and coating it with a painting originally used in 1930s. The comparisons between the corrosion of the three sets of samples suggest that the Iulia Felix glasses could have been prepared with the same technique.

Preparation and properties of scintillating glass doped with organic activators

A series of scintillating glasses were developed by doping organic activators into low melting temperature glasses according to different ratios. The fluorescence spectra and the transmission spectra of some scintillating glasses were explored and the actual concentration organic in scintillating glass was estimated. The results show that it is feasible to prepare the scintillating glass by doing organic scintillating activators into the low-melting glasses. There are two main reasons for the weak optical properties of the scintillation glasses: one is that the actual concentration of organic activators doped in the glasses is very low, and the other is the existence of lots of defects formed in the scintillating glasses due to the evaporation of organic activator, lowering the transmission of glasses. The fluorescence emission peaks of the glasses move to a longer wavelength compared with those in organic matrixes. To increase the light output of the glass, the optical transmittance of the glasses must be improved and the concentration of activators in the glasses must be increased.

Vibration micro-machining of low-melting temperature glass

This paper describes the machining properties of low-melting temperature (LMT) glass with a tiny vibrating tool (φ0.1 mm). Both the abrasive machining and cutting tests were carried out for groove machining including other glass materials for comparison. It was found that LMT glass could be cut without chipping and with smooth surface if the groove depth is shallow, whereas abrasive machining was preferable to improve profile accuracy in deep groove machining. The effects of various parameters such as tool geometry were made clear. That is, the tool should be rounded properly without sharp edges and the efficient removal of chips is crucial to obtain good results. The importance of the monitoring of the process is also emphasised.

Fusing silicon wafers with low melting temperature glass

Abstract This paper describes research on a low-temperature technique for fusing two silicon wafers together. The work has focused on integrating the bonding process with MOS IC processing. A seal that is apparently hermetic is achieved at 450 °C between wafers which have gone through the individual processing steps needed to fabricate MOS capacitors and electrical leads through the sealed package. In order to use this process to bond at low temperature, the bonding surfaces must be smooth, clean, and phosphorus free.

Crystallization of Silicon Films on Glass: A Comparison of Methods

ABSTRACTThe lure of flat panel displays has stimulated much research on the crystallization of silicon films deposited on large-area transparent substrates. In most respects, fused quartz is ideal. It has high purity, thermal shock resistance, and a softening point above the silicon melting temperature. Unfortunately, fused quartz has such a small thermal expansion that the silicon film cracks as it cools. This problem has been attacked by patterning with islands or moats before and after crystallization, by capping, and by using silicate glass substrates that match the thermal expansion of silicon. The relative merits of these methods are compared. Melting of the silicon film to achieve high mobility has been accomplished by a variety of methods including lasers, electron beams, and strip heaters. For low melting temperature glasses, surface heating with a laser or electron beam is essential. Larger grains are obtained with the high bias temperature, strip heater techniques The low-angle grain boundaries characteristic of these films may be caused by constitutional undercooling. A model is developed to predict the boundary spacing as a function of scan rate and temperature gradient.

高レベル放射性廃棄物（模擬）含有ホウケイ酸塩ガラスの性能評価

In connection with the development of vitrified solidification processes of high-level liquid wastes at Power Reactor and Nuclear Fuel Development Corp. (PNC), the characterization of the various borosilicate glasses containing the simulated high-level radioactive wastes have been carried out at Government Industrial Research Institute, Osaka.The volatility, the viscosity and the electrical conductivity of glasses in molten states have been measured, and the thermal conductivity, the elastic modulus, the chemical durability and the crystallization behavior in solid states have been also investigated. These data seem to be useful in the construction and operation of the engineering scale faci1ity at PNC.The low-melting temperature glasses have large volatilization rates, low viscosities in molten states, low crystallization temperatures and less durabilities with water in solid states. Therefore, the high-melting temperature glasses seem to be suitable for storage of wastes from the view point of safety evaluation, although in this case it is necessary to improve the melting technique to avoid violent evaporation.

Infrared measurement of the optical constants of the low melting temperature glass system of 30% arsenic — 34% sulfur — 36% thallium

The low melting temperature, heavy metal sulfide glass system of arsenic, sulfur, and thallium has proven to be optically clear from 1 to 23 μ in wavelength. The optical constants, consisting of absorption coefficient, reflection coefficient, extinction coefficient, and refractive index, have been determined from 2 to 23 μ in wavelength. The reflection coefficient was calculated from a plot of transmission measurements as a function of sample thickness, extrapolated to zero thickness. In turn, this data, through the application of the Kramers-Kronig relationship, has yielded both the real and imaginary portions of the refractive index. As a result of the low working temperature of this composition glass, the possibility exists of manufacturing lenses and domes by molding between Teflon dies and other materials.