Table of contents

Eu doped high silica glass prepared by sintering porous glass exhibits blue luminescence with high quantum efficiency. In this work, we studied effects of sintering temperature on valance state of europium ion. To investigate a change of valance state of Eu, X-ray absorption near edge structure (XANES) spectroscopy measurements were carried out. Intensity of blue emission at around 430nm drastically increases when the sintering temperature is above 1000°C. From XANES spectra, it is found that almost all the Eu exist as Eu³⁺ in a samples sintered below 900°C, while more than 70% of Eu exist as Eu²⁺ in the sample sintered at 1050°C and 1100°C. The drastic change of oxidation state of europium ion between 900 and 1050°C is discussed in relation to the structural change probed by infrared (IR) spectroscopy.

We investigated crystallization behaviour of several glasses in ternary Li₂O-ZnO-GeO₂ system in order to fabricate the glass-ceramics consisting of Zn-related compound showing photoluminescent property. Nanocrystallized glass with willemite-type Zn₂GeO₄ could be prepared from the 15Li₂O-15ZnO-70GeO₂ glass, and revealed a long-lasting photoluminescence (LLP). Origin of the LLP in the nanocrystallized glass is also discussed.

It has been reported that the fragility in the AgI-Ag₂O-M_xO_y (M = B, Ge, P, Mo) system is determined by Ag₂O-M_xO_y and does not depend on the amount of AgI. This is an interesting result and provides a hint to understand the nature of the glassy state of these materials. However, the origin of such behavior has not been sufficiently discussed. In the present report a model for the above behavior is presented. According to the model, the behavior arises from the solid like nature of the network formed by Ag₂O-M_xO_y and the liquid like AgI which flow between the networks. The model is consistent with the structural model of superionic glasses proposed previously.

The composition dependence of boson peaks has been studied by Raman scattering in lithium and cesium borate glass, xM₂O-(_1−x)B₂O₃ (M = Li, Cs). The boson peak frequency markedly increases for the increase of the lithium composition, while for the cesium composition the boson peak frequency is nearly constant. It is found that the boson peak frequency clearly correlates with shear modulus. The origin of the boson peak of lithium and cesium borate binary glass is probably the coupled vibration of the libration of boroxol rings and rattling like vibrations of alkali ions. All observed boson peaks of lithium borate glass is scaled by the master curve. It indicates that the distribution of V-DOS remains the same in lithium borate glass. While, the broadening of a boson peak is observed in cesium borate glass. The extension of the distribution of V-DOS is induced probably by the large coordination number of Cs ions inserted in the network structure.

Technique of T-x-y diagram for system CaO-Al₂O₃-SiO₂ computer simulation by the use of kinematical surfaces has been suggested. Original 245 crystallization paths were found.

Scattered neutron diagnostics is an indispensable tool for both inertial confinement and magnetic confinement fusion research. For this purpose, a fast-response neutron scintillator with a high cross section for scattered neutrons is strongly required. Recently, based on our material design strategy, we have successfully developed the fast response time Pr³⁺-doped 20Al(PO₃)₃-80LiF glass scintillator for scattered neutron originated from inertial confinement fusion. The matrix glass 20Al(PO₃)₃-80LiF shows good glass forming ability, chemical durability and transparency in the deep ultraviolet region. The purpose of this work is to investigate the glass structure of 20Al(PO₃)₃-80LiF glasses using Raman spectroscopy and to discuss the relationship between physical and scintillation properties and glass structure.

We have succeeded in precipitation of silicon nanoparticles inside silicate glass containing Al metal film using femtosecond laser irradiation. The Al-inserted sandwiched glass was fabricated by direct bonding. Raman spectra indicated that silicon particles were formed at the interface between the glass and the Al film after the fs laser irradiation. In addition, the crystallinity of silicon particles was dramatically changed by changing the laser irradiation conditions; amorphous and crystalline silicon were formed by 1 kHz and 250 kHz fs laser irradiation, respectively. The deposited silicon was detected at an area 1 μm away from the focal point perpendicular to the direction of incident laser beam.

In this work, properties of glass from local rice husk ash (RHA) in Thailand have been investigated. RHA was sintered in different temperature. Compositions and phases of RHA were analyzed by energy dispersive x-ray fluorescence spectrometer (EDXRF) and X-ray diffractometer (XRD). The glasses were melt from RHA in formula 20 Na₂O : 1.0 Al₂O₃ : 13 B₂O₃ : 6.3 CaO : 0.2 Sb₂O₃ : 4.5 BaO : 55SiO₂ (using RHA as a SiO₂ source) The density values of all RHA glasses are comparable and larger than glass from pure SiO₂ under same glass formula and preparing condition. These results are corresponding with refractive index values. The RHA glasses showing colorless with absorption edge in ultraviolet region were obtained. The dark blue color glasses were melted from RHA with different CoO concentration. From this part, not found to be the relation of density and refractive index of glass with CoO concentration in glass matrix. From absorption spectra, the absorption peak were appeared around 600 nm, and peak intensity are increased, with increase CoO, correspond to ⁴A₂(⁴F) → ⁴T₁(⁴P) state of Co²⁺ in tetrahedral symmetry.

We performed in-situ inelastic light scattering measurement in KNbGeO₅ glass with a high nucleation ability during heating in order to elucidate nanocrystallization dynamics. The results of the in-situ measurement and TEM observation revealed that nanometric heterogeneous region (∼1-2 nm) consisting of the Nb-richer phase develops, i.e., K₃Nb₇O₁₉, at the temperature, in which glassy–supercooled-liquid (SCL) phase-transition occurs, i.e., precursive stage of nanocrystallization. This strongly suggests that evolution of the nanometric Nb-richer phase in the SCL phase corresponds to nucleation in the KNbGeO₅ glass.

An innovative in-flight glass melting technology was developed for a purpose of energy saving and environmental protection. Granulated glass raw materials with small diameter were treated by twelve-phase AC arc and that combined with an oxygen burner. The particle measurement was carried out to investigate the in-flight melting behavior of glass raw materials during the in-flight melting by twelve-phase AC arc. Obtained results show the mean particle velocity was about 9 m s⁻¹ and mean temperature was about 2600 K. The high vitrification degree achieved within several milliseconds reveals that the new in-flight melting technology of hybrid plasma treating can reduce energy consumption and shorten the glass production cycle.

In this work, we observed a non-ring–shaped Raman image in a region inside sodium germinate glass irradiated by a 250-KHz femtosecond laser. We deducted from Raman spectra that the molecular arrangement of the radial orientation in the laser-irradiated area was responsible for the observed Raman image results.

We report on the fabrication of optical waveguides and the precipitation of nonlinear optical crystals inside glass caused by local element migration with high-repetition femtosecond laser irradiation. Elements that contribute to the high refractive index migrated to the center of the focal region because of the femtosecond laser irradiation in phosphate and borate glasses. Based on this result, we successfully wrote optical waveguides in these glasses, where element distributions were continuously induced along a path traversed by the focal point. Furthermore, we succeeded in space-selective precipitation of nonlinear optical crystals such as β-BBO inside glass by controlling the thermophysical property (crystallization temperature).

We previously reported Faraday rotation of EuO-Al₂O₃-SiO₂ glass operating in the visible region. At that time, magnetic/magnetooptic improvement of EuO-Al₂O₃-SiO₂ glasses could be expected by incorporating divalent transition metal ions M²⁺ such as Co²⁺ and Fe²⁺ ions. In this paper, we report magnetic and optical properties of 70EuAl₂O₄-30SiO₂ glasses doped with Co²⁺ or Fe²⁺ ions. Faraday rotation effects of these glasses are also presented. Conclusively, it is revealed that the ferromagnetic couplings of the dimmer Eu²⁺ ↑ -Fe²⁺ ↑ and the trimer Eu²⁺ ↑ -Co²⁺ ↑ -Eu²⁺ ↑ formed in the glasses enhance Faraday Rotation effects.

The change of the viscoelastic flow near the imprinting temperature was analyzed by a penetration method with a commercial TMA and the result was compared with thermally-imprinted SnO-P₂O₅ (SP) and SnO-B₂O₃-P₂O₅ (SBP) glass samples by an imprint apparatus. The viscosity of SP glass increases monotonically with increasing SnO content and the specific movement is shown in viscoelastic flow under the optimized thermal imprinting temperature for SP glasses.

Surface crystallized glass ceramics with fresnoite (Ba₂TiSi₂O₈) phase were prepared by conventional heat treatment of 30BaO-20TiO₂-50SiO₂ glass together with ultrasonic surface treatment (UST) technique. The precursor glass was fully crystallized in a bulk form without any cracks, and the optical transparency and crystallographic orientation of the crystalline layers were evaluated by UV-Vis spectroscopy and XRD diffraction analyses, respectively. These properties were both enhanced significantly by applying UST using fresnoite/water suspension before the crystallization process, which is advantage for nonlinear optical applications of bulk glass ceramics. The effects of UST on the crystallization behavior were investigated by applying UST with various conditions.

The results of research aimed at the study on frits and glass-ceramic glazes for floor tiles, based on compositions located in the primary field of cordierite crystallization within the system MgO-Al₂O₃-SiO₂, have been presented.

The results comprise investigations on the frits crystallization abilities, stability of the crystallizing phase under conditions of single-stage a fast firing cycle (time below 60 minutes) depending on their chemical composition and the influence of the nucleation agents. The influence of the nucleating agents namely TiO₂, ZrO₂, V₂O₅ on phase composition of obtained crystalline glazes, mechanical parameters and microstructure, has been examined.

The strength tests proved increased mechanical resistance of crystalline glazes. Obtained glazes are characterized by high microhardness in range 6∼8 GPa, as well as the increased wear resistance measured by the loss of weight below 100 mg / 55 cm² (PN-EN ISO 10545-7). Significant increase of these parameters as compared with non-crystalline glazes, where micro-hardness values range between 5∼6 GPa and the wear resistance values range from 120 to 200 mg, has been proved.

Starting glasses (frits) and glazes of the ternary system MgO-SiO₂-Al₂O₃, were examined with use of DTA, XRD and SEM methods.

The bond fluctuation model of superionic conductors predicts that the polarizability of solids that exhibit high ionic conduction is large. Based on this background, a study on the nonlinear optical constants in superionic glasses has been started. As a first step, the relationship between the third-order susceptibility χ⁽³⁾ and the linear susceptibility χ⁽¹⁾ of various kinds of glasses has been studied. It is found that the values of χ⁽³⁾ of superionic conducting glasses exceed considerably the values predicted by the usual Miller rule. The deviation arises from the increase of the ionic coordinate dependent electronic polarizability, which plays also an important role in the ion transport processes.

The planar waveguides of 12Na₂O·10NbO_2.5·25WO₃·53TeO₂+1Er₂O₃ ([NbWEr]) glasses were prepared by Ag⁺-Na⁺ ion-exchange at 320-380°C for 5-30 h. The optical properties of the waveguides were characterized. Waveguiding property was successfully confirmed under all the ion-exchange conditions in this study. The thickness of the waveguides increased with increasing ion-exchange temperature and time. The minimum propagation loss of the waveguides was approximately 0.8 dB/cm at 632.8 nm. Hence, the [NbWEr] glass waveguides were considered to be promising for broadband optical amplifiers.

Flaws existing on glass surface can be divided into two types, extrinsic and intrinsic. Although the extrinsic flaws are generated during processing and using, the intrinsic flaws are regarded as structural defects which result from thermal fluctuation. It is known that the extrinsic flaws determine glass strength, but effects of the intrinsic flaws on the glass strength are still unclear. Since it is considered that the averaged bond-strength and the intrinsic flaw would affect the intrinsic strength, the intrinsic strength of glass surely depends on the glass composition. In this study, the intrinsic failure strain of the glass fibers with the compositions of 20Na₂O-40xB₂O₃-(80-40x)SiO₂ (mol%, x = 0, 0.5, 1.0, 1.5) were measured by using a two-point bending technique. The failure strength was estimated from the failure strain and Young's modulus of glass. It is elucidated that two-point bending strength of glass fiber decreases with increasing B₂O₃ content in glass. The effects of the glass composition on the intrinsic strength are discussed in terms of elastic and inelastic deformation behaviors prior to fracture.

Brazil is the world's largest producer of alcohol and sugar from sugarcane. Currently, sugarcane bagasse is burned in boilers to produce steam and electrical energy, producing a huge volume of ash. The major component of the ash is SiO₂, and among the minor components there are some mineralizing agents or fluxing. Published works have shown the potential of transforming silicate-based residues into glass-ceramic products of great utility. This work reports the research results of SCBA use to produce glass-ceramics with wollastonite, rankinite and gehlenite as the major phases. These silicates have important applications as building industry materials, principally wollastonite, due to their special properties: high resistance to weathering, zero water absorption, and hardness among others. The glasses (frits) were prepared mixing ash, calcium carbonate and sodium or potassium carbonates as flux agents, in different concentrations. X-ray fluorescence was used to determine the chemical composition of the glasses and their crystallization was assessed by using thermal analysis (DTA/DSC/TGA) and X-ray diffraction. The crystallization kinetics was evaluated using the Kissinger method, giving activation energies ranging from 200 to 600 kJ/mol.

We investigated the phase separation behavior of multi-component oxide glasses for coating layer of sanitary wares, and the holding time dependence of the microstructure and the coloring nature of phase separated glasses. Two kinds of multi-component silicate glasses (CaO-SiO₂-Al₂O₃-MgO-ZnO-K₂O-Na₂O system) were employed, which had different CaO/SiO₂ ratio. Glass A has higher CaO/SiO₂ ratio, and glass B has lower CaO/SiO₂. Quenched glasses that were pre-melted at 1550 °C for 90 min in advance, were isothermally held at 800∼1100 °C for 0.5∼2 h by the hot-thermocouple. The microstructure of phase-separated glass was observed by using FE-SEM on the polished section. It was found that the glass A and B heat-treated at given temperatures indicated a spinodal and a binodal type phase separation, respectively. Moreover, the glass A was found to have the larger microstructure of phase separation, which caused whitish color. In contrast, the glass B revealed the finer binodal phase separation that resulted in a bluish phase separated glass.

Sodium borosilicate glasses containing P₂O₅ and Al₂O₃ were prepared, and the behavior of phosphorus associated with the phase separation and the effect of Al₂O₃ addition have been investigated. After the heat treatment, phase separation by spinodal decomposition was observed in the all samples. In the Al₂O₃-free glasses, phosphorus was preferentially distributed into B₂O₃-rich glass phase after the phase separation. With increasing Al₂O₃ content, the amount of phosphorus distributed into SiO₂-rich glass phase increased. According to ³¹P MAS NMR measurements, in the Al₂O₃-containing glasses, Q⁴ units free from terminal oxygen atoms were formed. It was suggested that the distribution of phosphorus depend on the PO₄ units.