• 한국세라믹학회지
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• 제34권7호
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• pp.781-789
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• 1997

Pressure sintered SiC specimens were joined using MgO-Al2O3-SiO2 (MAS) glass which has a thermal expansion coefficient similar to that of SiC. MAS melt showed excellent behavior of wetting on the SiC substrate over 148$0^{\circ}C$, and the wettability was much influenced by the joining atmosphere. The joining was conducted at 150$0^{\circ}C$ for 30 min in Ar atmosphere. The flexural strength of the joined specimen shows 342~380 MPa up to 80$0^{\circ}C$, which is almost the same as that of as-recieved SiC specimen. However, the flexural strength of the joined specimen decreased to about 80 MPa at 90$0^{\circ}C$ due to softening of the glass melt. The analyses od XRD and WDS show that the reaction between the SiC specimen and the MAS melt produces the oxycarbide glass, which had a high strength and a good stability at high temperatures.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2008년도 추계학술발표대회 및 제15회 신소재 심포지엄
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• pp.41.1-41.1
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• 2008

• 한국광물학회지
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• 제28권1호
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• pp.61-69
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• 2015

현무암과 포놀라이트 조성을 가진 마그마는 분화 양상과 거시적 물성에서 많은 차이를 보이나 이에 대한 원자구조 단위의 근본적인 원인은 아직 명확히 밝혀지지 않았다. 본 연구에서는 일차원과 고해상도 이차원 고상 핵자기공명 분광분석(Nuclear Magnetic Resonance, NMR)을 이용하여 현무암질 마그마의 모델인 투휘석과 아노르다이트 공융점 조성을 가진 비정질 규산염과 포놀라이트 조성의 비정질 규산염의 Al 주변 원자 구조를 관찰하였다. $^{27}Al$ MAS NMR 실험 결과 두 조성 모두 Al 피크가 지배적인 것을 보여주며 현무암 조성의 비정질 규산염의 피크 반치폭이 포놀라이트 조성보다 약 2배 더 넓은 것으로 관찰된다. 이것은 현무암질 조성에서의 Al 주변의 위상 무질서도가 포놀라이트 조성보다 높다는 것을 의미한다. $^{27}Al$ 3QMAS NMR 실험 결과 Al과 Al이 구별되어 관찰되며 현무암 조성의 비정질 규산염에서 포놀라이트 조성에는 관찰되지 않는 Al이 약 3.3% 관찰된다. 이는 현무암질 마그마가 포놀라이트 마그마에 비해 Al 주변의 배열 무질서도가 더 큰 것을 의미한다. 사중극자 상호관계를 설명하는 계수 또한 현무암 조성의 비정질 규산염이 포놀라이트 조성의 비정질 규산염에 비해 큰 값을 나타내며 이것 또한 Al 주변의 위상 무질서도가 더 큰 것을 확증해준다. 본 논문에서 규명한 현무암과 포놀라이트 조성의 비정질 규산염의 원자 구조 차이는 점성도와 같은 조성에 따른 마그마의 물성 차이에 대한 미시적 기원을 제시한다.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.119-126
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• 2022

MAS-based glass, which has been studied to replace the ceramic material used in the plasma etching chamber, has problems such as forming and processing due to its high melting temperature. To solve this problem, in this study, fluoride was added to the existing MAS-based glass to increase the workability in the glass manufacturing and to improve the chemical resistance to CF₄/Ar/O₂ plasma gas. Through RAMAN analysis, the structural change of the glass according to the addition of fluoride was observed. In addition, it was confirmed that high-temperature viscosity and thermal properties decreased as the fluoride content increased and plasma resistance was maintained, it showed an excellent etching rate of up to 11 times compared to quartz glass.

• 한국세라믹학회지
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• 제38권12호
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• pp.1137-1143
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• 2001

본 연구에서는 적외선 반사체 제조를 위하여 MAS(MgO-Al$_2$O$_3$-SiO$_2$)계 유리로부터 핵행성 및 결정성장의 2단계 열처리에 의해 cordierite(2MgO.2Al$_2$O$_3$5SiO$_2$)와 rutile(TiO$_2$)을 주결정상으로 하는 결정화유리를 제조하였다. MgO-Al$_2$O$_3$-SiO$_2$3성분계 조성에 조핵제로 TiO$_2$를 첨가하여 용융법으로 유리를 제조한 후 결정화 열처리를 하여 핵생성 및 결정화 거동과 결정화유리의 결정상, 입자 크기와 확산 반사율과의 관계를 관찰하였다. 그 결과 75$0^{\circ}C$에서 3시간동안 핵생성 시킨 후 110$0^{\circ}C$/5hr 이상의 열처리 조건에서 cordierite와 rutile이 주결정상으로 석출되었으며 570~2500nm 범위에서 90% 이상의 반사율을 갖는 결정화유리를 제조하였다.

• Bulletin of the Korean Chemical Society
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• 제17권8호
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• pp.696-699
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• 1996

Silicate and borosilicate gels were prepared by the sol-gel process and thermally treated in the 150-850 ℃ temperature range. Solid-state 1H MAS and 29Si CP/MAS NMR spectroscopy were used to investigate the effects of heat treatments on the silicate gel to glass conversion process. The 1H NMR isotropic chemical shifts and the relative intensities of hydrogen bonded and isolated silanol groups have been used to access the information concerning the dehydration process on the silicate gel surface. The 29Si NMR isotropic chemical shifts affected by the local silicon environment have been used to determine the degree of crosslinking, i.e. the number of siloxane bonds. These NMR results suggest that the silicate gel to glass conversion process is occurred by two stages which are dependent on the temperature; (1) the formation of particles up to 450 ℃ and (2) the formation of large particles by aggregation of each separated single particle above 450 ℃. In addition, the effects of B atom on the formation of borosiloxane bonds in borosilicates have been discussed.

• The Korean Journal of Ceramics
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• 제5권2호
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• pp.178-182
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• 1999

Simple binary $Na_2S-SiO_2$ oxysulfide glasses were prepared by a conventional melt-quench method in order to investigate the role of sulfur in glass structure and the electronic state. By X-ray photoelectron spectroscopy(XPS) measurement, S2p binding energy of the glass was observed at approximately 161eV which was close to that of ionic $S^{2-}$. The coordinating state around silicon atoms were investigated by ${29}^Si$ MAS-NMR measurement. The chemical shift observed from NMR supported that sulfur atom was joined to a silicon atom by substituting for an oxygen atom and was present as a non-bridging sulfide ion in low alkali content. On the other hand, it could be presumed that a portion of sulfur anions existed in an isolated state from the glass-network frame at high alkali content. The state of these sulfurs was also studied by Raman spectroscopy in detail.

• 반도체디스플레이기술학회지
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• 제20권2호
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• pp.61-66
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• 2021

In this study, we studied the alternative of plasma resistant ceramic parts that constitute plasma chambers in the semiconductor dry etching process. MgO-Al₂O₃-SiO₂(MAS) glass was made of 13 types of glass using the Design Of Experiments(DOE) and the effect on thermal properties such as glass transition temperature and crystallization temperature depending on the content of each composition and etching resistance to CF₄/O₂/Ar plasma gas. MAS glass showed excellent plasma resistance and surface roughness up to 20 times higher than quartz glass. As the content of Al₂O₃ and MgO increases, the plasma resistance is improved, and it has been confirmed that it has an inverse relationship with SiO₂.

• 한국자기공명학회논문지
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• 제9권1호
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• pp.61-66
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• 2005

$^{11}B MAS NMR$ spectra of binary glass system $xV_2O5-B_2O_3$ and ternary glass system $xV_2O5-B_2O_3-yNa_2O$ (x = $V_2O_5 mol%/$B_2O_3$ mol%, y = $Na_2O$ mol$/$B_2O_3$ mol%) were acquired. $BO_3$ units are dominant components in the spectra of $xV_2O_5-B_2O_3$glass systems while both $BO_3$ and $BO_4$ unit appear in comparable amounts in the spectra of $xV_2O_5-B_2O_3-yNa_2O$ glass systems. More $BO_3$ units were monitored for higher $V_2O_5$ contents while more $BO_4$ unit for higher $Na_2O$ contents. Quadrupole parameters such as $e^2qQ$ and $\eta$ obtained form spectral simulation indicate that $e^2qQ$ has a maximum value at x = y 1 and $\eta$ decreases and increases as x or y grows, respectively. Our results suggest that $V_2O_5$ and $Na_2O$ play opposite roles in the ternary glasses.

• Bulletin of the Korean Chemical Society
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• 제30권3호
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• pp.608-612
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• 2009

The local structures of the boron and vanadium sites in the ternary glass $xV_2O_5-B_2O_3-yNa_2O$ were studied by $^{11}B\;and\;^{51}V$ magic angle spinning (MAS) nuclear magnetic resonance (NMR). With increasing x, the mole ratios of the $BO_3\;and\;BO_4$ structures were enhanced, as were the quadrupole asymmetry parameters for the $BO_3$ structures, while the quadrupole coupling constants for the sites were reduced. However, the opposite trends were observed with increasing y, implying that $V_2O_5$ and $Na_2O$ play opposite roles. The $VO_4,\;VO_5\;and\;VO_6$ structures with all oxygens bonded to the vanadium neighbors were identified. Vanadiums bonded to the greater number of oxygens were more populated at higher contents of $Na_2O\;and\;V_2O_5$. In addition, the $VO_4$ structures with at least one oxygen bonded to boron instead of vanadium were detected at low $Na_2O$ contents. The electron densities of various vanadium oxide structures were affected by the weight densities and vanadium ion densities. The $VO_4$ structures were more likely to be vanadium oxide structures right next to $V4^{+}$ ions.