Chemical Composition of Glass

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Abstract

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 4 hr at 1250ºC 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.

Introduction

Chemical composition of glasses showed an important role in determining properties of them. Glass is ordinary contained with three main parts; network former, network modifier and intermediate species which fall somewhere between network former and modifier [1, 2]. Oxide glasses containing transition metal ions are very interesting because of their potential and wide range of applications such as switching and memory devices, transducers, insulators and dielectrics [3, 4], that are widely applied in many fields; information technology, energy and infrared detection [5]. In general, transition metal ions can exist in multivalent states depending upon the base glass composition, melting temperature and time, and pressure conditions [6]. Among these elements, prime attention should be paid to iron [7]. The addition ...

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... a superlene sample holder prior to being loaded into the sample chamber. The x-ray beam was of 1 mm x 10 mm rectangular shape. Energy calibration was achieved with Fu foil standard and the position of the first inflection point was taken at 7112 eV (±0.2 eV). Reference spectra were also collected on pyrite and hematite powders.

Results and discussion

It was found that the colors of the glass samples were changed from colorless to dark brown.

The specific gravity and refractive index were increased with increasing Fe2O3 contents, from 2.5521 to 2.6562 and 1.51 to 1.52, respectively, as detailed in Table 1 and Figure 2 (a and b).

The dielectric constant was increased with increasing Fe2O3 contents, as shown in Figure 2 (c). It was also found that the dielectric constant depend with the frequencies; the higher frequency, the lower dielectric constant.

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