• Title/Summary/Keyword: Chemical composition of glass

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Sintering and Dielectric Properties in Cordierite/Glass Composite for LTCC Application (Cordierite/Glass Composite계 LTCC 소재의 소결 및 유전특성)

  • Hwang, Il-Sun;Yeo, Dong-Hun;Shin, Hyo-Soon;Kim, Jong-Hee
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.2
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    • pp.144-150
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    • 2008
  • Recently, there has been growing interest in low loss and low dielectric constant material for LTCC application, as the frequency range for electronic devices increases. This study was designed to evaluate the effect of cordierite filler for low dielectric constant LTCC material. From the previous experiments, two glass compositions of B-Si-Al-Zn-Ba-Ca-O and B-Si-Al-Sr-Ca-O system, were chosen. Each powder of two glass compositions was sintered respectively with commercial cordierite powder in temperature range from $800^{\circ}C\;to\;900^{\circ}C$. Crystalline cordierite and glass peaks were affected only with two factors of composition and sintering temperature among various factors. With the optimized condition of two cordierite/glass compositions, obtained dielectric constant was below 5.5 and quality factor was above 1,000. Closed pore of sintered body was controled by sintering temperature and sintering time. When cordierite/glass composite with ratio of 5.5:4.5 was sintered at $900^{\circ}C$, densification was sufficient with good dielectric characteristics of ${\epsilon}_r<5.1,\;Q{\ge}1,000$. Residual fine closed pores could be reduced with control of sintering temperature and time. 3 point bending strength and chemical durability were evaluated to obtain feasibility for substrate material.

Evaluations of Sb20Se80-xGex (x = 10, 15, 20, and 25) Glass Stability from Thermal, Structural and Optical Properties for IR Lens Application

  • Jung, Gun-Hong;Kong, Heon;Yeo, Jong-Bin;Lee, Hyun-Yong
    • Journal of the Korean Ceramic Society
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    • v.54 no.6
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    • pp.484-491
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    • 2017
  • Chalcogenide glasses have been investigated in their thermodynamic, structural, and optical properties for application in various opto-electronic devices. In this study, the $Sb_{20}Se_{80-x}Ge_x$ with x = 10, 15, 20, and 25 were selected to investigate the glass stability according to germanium ratios. The thermal, structural, and optical properties of these glasses were measured by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and UV-Vis-IR Spectrophotometry, respectively. The DSC results revealed that $Ge_{20}Sb_{20}Se_{60}$ composition showing the best glass stability theoretically results due to a lower glass transition activation energy of 230 kJ/mol and higher crystallization activation energy of 260 kJ/mol. The structural and optical analyses of annealed thin films were carried out. The XRD analysis reveals obvious results associated with glass stabilities. The values of slope U, derived from optical analysis, offered information on the atomic and electronic configuration in Urbach tails, associated with the glass stability.

Photoinduced Superhydrophilicity in TiO2 Thin Films Modified with WO3

  • Hwang, Young-Kyu;Patil, Kashinath Rangu;Kim, Hye-Kyung;Dattatraya Sathaye, Shivaram;Hwang, Jin-Soo;Park, Sang-Eon;Chang, Jong-San
    • Bulletin of the Korean Chemical Society
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    • v.26 no.10
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    • pp.1515-1519
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    • 2005
  • Tungsten oxide-modified TiO2 thin films were formed on a glass substrate by sol-gel and dip coating processes using acetyl acetone as a chelating agent. The hydrophilic properties of the thin films were investigated with illumination of UV light. The dependence of water contact angle on material composition and morphology of the film is established with SEM image and AFM profile. The surface morphology was controlled with the change of precursor concentration. 0.01 M of tungsten oxide-modified Ti$O_2$ have shown the highest hydrophilicity after UV-irradiation. The effect of composition on photoinduced hydrophilicity of the W$O_3$-Ti$O_2$ films was also investigated. The films were characterized by XRD, SEM, AFM and XPS.

Preparation of High Transparent Olefin Copolymer with Metallocene Catalyst

  • Lee, Dong-Ho;Choi, Yeon-Seok;Ha, Ki-Ryong
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.1028-1029
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    • 2003
  • The copolymerization of ethylene and norbornene was carried out with ansa-metallocene and modified methylaluminoxane (MMAO) cocatalyst. The copolymerization behavior was changed with the structure of metallocene catalysts. In addition the catalyst activity was dependent on the structure of MMAO, i.e.. MMAO-4 which contains less i-butyl group compared to MMAO-3A exhibited higher catalyst activity than MMAO-3A. The glass transition temperature and the composition of the produced copolymer were not affected by MMAO type.

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Partitioning effects and corrosion characteristics of oxyapatite glass-ceramic wasteforms sequestering rare-earth elements

  • Kim, Miae;Kang, Jaehyuk;Yoon, Jang-Hee;Lee, Sang-Geul;Um, Wooyong;Kim, Hyun Gyu
    • Nuclear Engineering and Technology
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    • v.54 no.3
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    • pp.997-1002
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    • 2022
  • Oxyapatite[Ca2Nd8(SiO4)6O2] glass-ceramics have been suggested as wasteforms for the immobilisation of rare-earth radioactive nuclides because of their high waste-loading capability and good chemical durability. In particular, a partitioning effect is predicted to contribute to an enhancement of corrosion resistance in glass-ceramics compared with that of conjugate glasses of the same composition. Because rare-earths are inherently insoluble nuclides, detection of changes in corrosion behavior between glass-ceramics and conjugate glasses under normal conditions is not easy. In this study, therefore, we revealed the partitioning effect by exposing glass-ceramics and glasses to solution of pH 2, 7 and 10 at 90 ℃ for 20 d. In addition, we proposed the corrosion mechanism for oxyapatite glass-ceramics under various corrosion conditions. Especially, the glassy phase dissolved first, followed by the oxyapatite phase during pH 7 corrosion.

A Study on the Thermal Properties and Plasma Resistance of Bi2O3-Al2O3-SiO2 Glass (Bi2O3-Al2O3-SiO2 유리의 열물성과 내플라즈마 특성 연구)

  • Young Min Byun;Jae Ho Choi;Won Bin Im;Hyeong Jun Kim
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.1
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    • pp.64-71
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    • 2023
  • In this study, we investigated the effects of BiAlSiO glass composition on its glass forming range, thermal properties, and plasma resistance. The results showed that increasing the Al2O3 content suppressed the tendency for crystallization and hindered glass formation beyond a certain threshold. Bi2O3 was found to increase the content of non-bridging oxygen, resulting in a decrease in glass transition temperature and an increase in thermal expansion coefficient. Furthermore, the etching rate was found to improve with increasing Al2O3 content but decrease with increasing SiO2 content. It was concluded that the boiling point of fluorinated compounds should be considered to 900℃. Therefore, this study is expected to contribute to the understanding of the properties of BiAlSiO glass and its application to low temperature melting PRG compositions.

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Material Analysis of the late 19th century to 20th century Women's Hats Ornaments in National Folk Museum of Korea (국립민속박물관 소장 19세기 말~20세기 여성용 쓰개 장식의 재질분석)

  • Lee, Sae Rom;Oh, Joon Suk;Hwang, Min Young
    • Journal of Conservation Science
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    • v.35 no.2
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    • pp.169-176
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    • 2019
  • The material composition of 19 ornaments used for women's hats in the late $19^{th}$ century to $20^{th}$ century, which are kept at National Folk Museum of Korea, was analyzed using SEM-EDS. Sixteen ornaments were composed of $Na_2O$ and PbO, which form adifferent lead glass from those that have been excavated or handed down since ancient times in Korea. The chemical composition analysis has confirmed that two ornaments belong to the mixed alkali glass, while one belongs to the potash glass IIItype. This lead glass is similar in composition to the Japanese craft lead glass that was imported to Joseon during the Japanese colonial era. It is estimated that the lead glass ornaments used in women's hats in the late $19^{th}$ century to $20^{th}$ century were made from raw materials imported from Japan or made from lead glass used for crafts in Japan. This shows that jewelry such as jade and amber, which have been traditionally used in the modern and present ages, have been replaced by craft lead glass imported from Japan.

Study of Littoral Sand Migration Along the West Coast of Ahnmyeon Island, Korea

  • Park, Yong Ahn
    • 한국해양학회지
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    • v.10 no.1
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    • pp.1-6
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    • 1975
  • A marine geological investigation of the glass sand deposit in the beach along the west coast of Ahnmyeon Island, South Chung Cheong Province, Korea was carried out to solve the problen of sand material migration, textural properties of the sands and the glass sand reserve for future exploitation. Several bos coring analyses by means of the internal sedimentary structure.i.e., cross- stratification show significantly that most sands are moving and accumulation along the mean vector direction of $N20^{\circ}E-N60^{\circ}$ E in the area investigated. The average mean size of the sand sediments in the area studied ranges from 0.212mm to 0.275mm. The mechanism of sand migration in the area is considered to be interplay between longshore drift and flood tidal current. The sorting value of the sands ranges from 0.24 to 0.50. Therefore, these sand sediments are characteristic to be "well sorted". The average chemical composition of the glass sand in the area is the following: $SiO\_2$:-90.8%, $Al_2O_3$: -2.18%, $Fe_2O_3$:-0.73%, CaO:-1.79. The binocular microscope examination of the sands show that most of the sands are characteristically ice- clear quartz in mineral composition and their count percentage is mostly 92% or 96%.

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A Characteristics Classification by Beads Analysis of the Tombs of Deokcheon-ri in Uljin, Korea. (울진 덕천리 신라묘군 출토 구슬류의 특성 고찰)

  • Lee, Minhee;Kim, Gyu-Ho
    • Conservation Science in Museum
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    • v.22
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    • pp.69-84
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    • 2019
  • This study investigated the formal characteristics and chemical compositions of eighty beads excavated from a Silla tomb complex at Deokcheon-ri, Uljin in order to reveal the methods of production and the characteristics of the raw materials involved, thereby illuminating characteristics of the relics from each tomb. The beads excavated from these Silla tombs include one curved bead, one tubular bead, and 78 globular beads. Among them, the curved and tubular beads and three globular beads were identified to be made of minerals, and the remaining 75 beads are made of glass. Most of the glass beads are thought to have been produced using the drawing technique. The characteristics of the beads were classified according to their site of excavation. The globular beads from Tomb No. 34 belong to the lead-barium glass and potash glass groups, indicating that these beads were produced at a relatively earlier period in time. The glass beads excavated from the tombs in the northern portion of the complex differ in color and chemical composition from those in the southern portion, which indicates the character that each group of beads had different aspect according to site location. Considering that the excavated beads were mainly from fifth- and sixth-century tombs, it is likely that certain groups of people living around Uljin used and buried beads in their tombs. As the governance of Silla became more centralized in the sixth century, the use of beads for burial purpose appears to have come to an end in this region.

Optical Properties of Soda-lime Color Glass Fabricated by Using Refused Coal Ore (석탄폐석을 이용한 소다라임계 컬러유리의 광학적 특성)

  • Lim, Tae-Young;Jeong, Sang-Su;Hwang, Jong-Hee;Kim, Jin-Ho;Kim, Jung-Kook
    • Korean Journal of Materials Research
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    • v.20 no.10
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    • pp.524-534
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    • 2010
  • Glass was fabricated using refused coal ore obtained from the Dogye coal mine in Samcheok. We additionally used soda ash and calcium carbonate to make a glass with the chemical composition of soda-lime glass, and we also used white, brown, and green glass cullet to make various kinds of colored glass. Transparent glass was fabricated by melting batch materials including refused coal ore at $1550^{\circ}C$ for 1 hr in an electrical furnace. The light transmittance and color chromaticity were measured by a UV/VIS/NIR spectrometer. Transparent glass with a light transmittance of over 80% was fabricated using normal refused coal ore and white glass cullet. Various kinds of colored glass with a light transmittance of 30-80% were fabricated using refused coal ore and brown or green glass cullet. The light transmittance of the mixed color glass samples, fabricated using normal refused coal ore and brown glass cullet and green glass cullet, indicated 30-47%, a relatively low value, in the condition of a cullet ratio of 20-50%. The characteristics of the color chromaticity of the glass samples were indicated in a chromaticity diagram by x-coordinates, y-coordinates, Y (lightness). The values of x-coordinates and y-coordinates were moved with a regular directional property according to the kind and amount of glass cullet. Therefore, we concluded that refused coal ore can be used for raw materials of color glass products like art glass and glass tile.