Narin Sirikulrat

Raman spectroscopic investigation on high refractive index glasses prepared from local quartz sand

High refractive index (RI) glasses prepared from local quartz sand and compounds of heavy elements, such as, barium carbonate, lead oxide, and bismuth oxide as major ingredients were investigated using Raman spectroscopy. The results showed changes in glass structures of different doping elements, namely, Ba, Pb, and Bi. Refractive indices, densities, and UV-vis-NIR spectra of the glass samples were also measured. The Raman spectroscopy can be used to investigate and/or identify heavy glasses, local ancient glasses as well as glass jewelry.

Lead-Free High Refractive Index Glasses Produced from Local Raw Materials

Many difference useful and decorative articles have been made from glasses over the centuries, especially lead-containing glasses. Due to harmful effects of lead from glass fabrication process on human beings and considering the health as well as the environmental issues, many researchers tried to produce leadless glasses using some heavy chemical elements such as barium, bismuth and zirconium. Nowadays, barium compounds seemed to be satisfactory and to be able to increase the refractive index. For production of high quality crystal glasses with high refractive index in Thailand, most raw materials including high quality sand have been imported. Because, Thailand, in fact, is rich in many kinds of raw materials for glass manufacturing, therefore, this work is set up to study the fabrication of the lead-free high refractive index glasses using local sand and barite as the main raw materials. After complete melting, the physical and optical properties of the prepared glass samples were determined to compare these properties with those of glasses prepared from foreign sand. It was found that the prepared glasses produced from local raw materials were suitably for restoration, decoration, radiation shielding, as well as glass jewelry. These glasses can be considered as one of the environmental friendly materials.

Effects of Gold Nanoparticles on the Fabrication of Red Colored High Refractive Index Lead Glass

Red colored gold ruby glass used for decorations in ancient times was actually gold nanotechnology at work by the addition of gold particles into molten lead glass. Most of high refractive index glasses are based on lead-bearing silicate glass. High refractive index lead glasses (HRLG) made from local sands and lead oxide were successfully fabricated both in laboratory and larger scales. In this study, gold metal was doped into the lead glass mixtures. Morphology of the prepared lead glass was observed using SEM and compared with that of the red colored Ancient Thai Glass (ATG). It was found that the fabricated red colored HRLG yielded similar color and clarity to the red colored ATG. From electron micrographs, the presence of gold in lead glass was in the form of nanoparticles. The optical properties of the glasses were also examined.

Study of Metal Coating on Lead-Free High Refractive Index Glass Prepared from Local Sand

Lead-containing glasses coated with lead metal have been used for decoration in Thailand for a long time, were a high refractive index glass. Due to harmful effects of lead, time degradation of glass and because of many kinds of local raw materials for glass production especially sand, colorless lead-free high refractive index glasses were prepared by using local raw materials. In this work, the various kinds of metals; silver and aluminum, were coated on the surface of the prepared glasses using both chemical and physical methods. The joining interfacial layer between the glass body and the coated layer was studied using a scanning electron microscope and the hardness of the coated glasses was measured by a microhardness tester to compare with those of lead coating. It was found that the structures between the joining interfacial layers were similar. The values of the Knoop hardness were approximately 520±20 kg/mm2. This glass can be used to replace the lead glass for restoration glass or decoration onto the surface of the new wood or the metal carving products.

X-Ray Spectrometry Study on Historical Decorative Glasses in Thailand: Lanna-Style Glass

t was known that historical objects were highly heterogeneous. Due to the complex nature of materials and objects, extremely sensitive, spatially resolved, multi-elemental and versatile analytical instruments were needed. The techniques employed should be as a noninvasive as possible and able to give complementary information from macroscopic to nanometer scales. In this work, X-ray based spectroscopy including energy dispersive X-ray fluorescence spectroscopy (EDS), Proton-induced X-ray emission spectroscopy (PIXE), and micro-beam X-ray fluorescence spectroscopy (µ-XRF) were used to analyze chemical composition of the Lanna-style glass. Microstructure was also studied. It can be concluded that these techniques in combination are powerful for the investigation of heterogeneous glassy materials.

Optical Analysis of Bismuth-Based Glasses Doped Potassium Chromate

In this study, Bismuth-based glasses were prepared and doped with various concentration of potassium chromate. They were melted in an electrical furnace at 1250°C for 4 hours then pressed with fire frame to plate shape and annealed at 500°C for 10 min. Optical spectra were used to analyze color shade of glasses. Homogeneity of glasses was analyzed by birefringence technique. Glasses color was changed from colorless to slightly and opaque green with an increasing amount of potassium dichromate and birefringence result showed that the glasses are non-homogenous.

Radiation shielding lead-free glass based on barium-bearing glass using Thailand Quartz sands

Lead glass that shows a high refractive index is the best known and most popular for radiation shielding glass. Due to the toxic of lead compounds on the human organisms as well as the environmental issues, lead free glass was fabricated by using some heavy elements such as barium and bismuth to replace lead. In this study, colorless lead free glass samples were prepared from 40 wt% local quartz sand and various concentration of BaCO3 (20-40 wt%) as the main compositions in order to study radiation shielding property. The glass mixtures were melted conventionally using electric furnace at the maximum temperature of 1250°C with 4 hr dwelling time. The gamma attenuation characteristics were studied for the photon energy of 662 keV from Cs-137. Density and refractive index were also determined. It was found that a variation of prepared glass samples can be produced both in terms of clarity and radiation shielding properties. The attenuation coefficients were linearly increased as the increase of BaCO3 content. The density and refractive index were also increased. The linear and mass attenuation coefficients of the glass sample containing 40 wt% BaCO3 were 0.234 cm-1 and 0.0726 cm2g-1. In conclusion, a low density glass samples will give rise less attenuation than a high density ones. It can be concluded that the lead-free high refractive index glass that is one of the environmental materials can be used as the gamma radiation shielding glass.

Optical, Dielectric and X-Ray Absorption Properties of Soda-Based Glass Fabricated from Thai Quartz Sands Doped with Iron Oxide

Soda-based glass samples were fabricated in a laboratory scale using quartz sands that was a by-product of feldspar floatation in Tak Province, northern Thailand, and 25-wt% commercial-grade Na2CO3 as the main compositions. Fe2O3 of 0.1 to 10.0 wt% concentrations was doped into the glass mixture. Well-mixed and dried powders were melted in a ceramic crucible for 6 h at 1250°C using an electric furnace. Transparent and bubble-free glass samples were obtained as results. It was found that Fe2O3 dopant turned the otherwise colorless glass to dark brown. Dielectric property and physical properties, such as, color, specific gravity, and refractive index of the glass samples were studied. The samples’ dielectric constant, specific gravity, and refractive index increased with increasing Fe2O3 doping concentration. UV-VIS-NIR and synchrotron-based X-ray absorption spectra were measured and discussed.

Analysis of barium-bearing glass doped with chromium oxide

Barium-bearing glass samples were fabricated in a laboratory scale using quartz sands that was a by-product of feldspar floatation in Tak Province, northern Thailand, and 30-wt% barite from Loei Province, northeastern Thailand, as the main compositions. Cr2O3 of concentrations ranging from 0.01 to 5.0 wt% was doped into the glass mixture. The dried powders were wellmixed in a ceramic crucible and melted in an electric furnace at 1250°C for 6 hr. Bubble-free glass samples were yielded after cooling down. The glass colors were changed from colorless to green by the addition of Cr2O3. Dielectric property, color, specific gravity, and refractive index of the glass samples were analyzed. It was found that dielectric constant, specific gravity, and refractive index increased with increasing amount of Cr2O3 dopant. Measurements of UV-VIS-NIR spectra and microstuctural analysis using scanning electron microscope were also carried out and discussed.