• Journal of the Korean Ceramic Society
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• v.16 no.3
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• pp.135-141
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• 1979

This study seeks to find optimum conditions for the heating schedule of the Diopside-Devitrite system, to find the amounts and the kinds of nucleus which effect the crystal growth and forming nucleus. Generally, crystallization in the glass depends on the number of nucleus growing in the internal system and the rate of crystal growth. In order to obtain homogeneous polystalline phae, Diopside as MgO source and $ZrO_2$.$P_2O_5$, $TiO_2$, NaF, $CaF_2$ as nucleating agents were added to the $Na_2O$.CaO.$6SiO_2$ glass. The results obtained were Summarized as follows. 1) Optimum Batch Composition of base glass is 76.82 wt.% $SiO_2$, 5.84 wt.% CaO, 4.54 wt.% MgO and 9.80 wt.% $Na_2O$. 2) Best heating schedule.140$0^{\circ}C$(Melting)coolinglongrightarrow95$0^{\circ}C$reheatinglongrightarrow$1100^{\circ}C$coolinglongrightarrowRoom Temp. 3) The optimum amounts of $ZrO_2$.$P_2O_5$, $TiO_2$ and $CaF_2$ are 3wt.% and that of NaF is 4 wt.% as a nucleating agents.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3303-3310
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• 2012

Two single crystals of fully dehydrated partially $Li^+$-exchanged zeolite X were prepared by the exchange of Na-X, $Na_{92}Si_{100}Al_{92}O_{384}$ (Si/Al = 1.09), with $Li^+$ using aqueous 0.1 M $LiNO_3$ at 293 (crystal 1) and 333 K(crystal 2), followed by vacuum dehydration at 623 K and $1{\times}10^{-6}$ Torr for 2 days. Their structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $Fd{\overline{3}}$ at 100(1) K. Their structures were refined using all intensities to the final error indices (using the 1281 and 883 reflections for which ($F_o$ > $4{\sigma}(F_o)$) $R_1/R_2$ = 0.075/0.244 and 0.074/0.223 for crystals 1 and 2, respectively. Their compositions are seen to be ${\mid}Li_{86}Na_6{\mid}[Si_{100}Al_{92}O_{384}]$-FAU and ${\mid}Li_{87}Na_5{\mid}[Si_{100}Al_{92}O_{384}]$-FAU, respectively. In crystal 1, 17 $Li^+$ ions per unit cell are at site I', 15 another site I', 30 at site II, and the remaining 16 at site III; 2 $Na^+$ ions are at site II and the remaining 4 at site III'. In crystal 2, 32 and 30 $Li^+$ ions per unit cell fill sites I' and II, respectively, and the remaining 25 at site III'; 2 and 3 $Na^+$ ions are found at sites II and III', respectively. The extent of $Li^+$ exchange increases slightly with increasing ion exchange temperature from 93% to 95%.

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.723-726
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• 2010

An efficient and simplified protocol for $NaHSO_4/SiO_2$ catalyzed solvent-free synthesis of $\beta$-enaminone and 2-methylquinolin-4(1H)-one derivatives under microwave irradiation is described. A series of functionalized derivatives have been synthesized in shorter reaction times with moderate to good yields. The use of milder catalyst in non-conventional method offers significant advantages over conventional methods, such as higher selectivities, simplicity, solvent-free reaction and non-environmental polluting conditions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.2 no.2
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• pp.20-32
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• 1992

$Na_2O-CaO-MgO-Al_2O_3-SiO_2$ glass was taken as a basic glass and then $Li_2O$ O.5wt%, $K_2O$ 2.0wt% were substituted to $Na_2O$content, MgO 12.0wt %, ZnO 6.0wt % to CaO content. And also nucleation agent $ZrO_2 and $CaF_2$ were added to 1-2wt% respectively. The crystal according to the compositions appeared wollastonite, diopside and diopside.tremolite. The glasses substituted NazO by LizO was decreased thermal expansion coeffcient but substituted by ZnO was opposite direction and both of them increased bending strength. In the ratio of ZrOz to CaF, each 1: 1 and 1: 2 have shown considerable crystal growth at $1000^{circ}C~1050^{\circ}C$ and high bending strength, but the glass in the ratio 1: 2 have shown lowest thermal expansion coefficient. The activation energy was at the glass in the ratio of ZrO, to CaFz 1:2 evaluated 55.24kvsl/mol by Ozawa type and 53.05kal/mol by kissinger type.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.1
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• pp.31-36
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• 1993

Na-Fe Tourmalene ($NaFe_3Al_6B_3Si_6O_{27}F_4$)single crystals were grown by FZ method. The Growth conditions are counter rotation 20~30rpm, growth rate 1~5mm/hr in the atmospheric environment. The transition elements as Fe(in this research), Mn, Co, etc, are exist in the theoretical fomulae so that dopants were not added. The feed rod was sintered between $1000^{\circ}C$ and $1l00^{\circ}C$, but at higher temperature, it was difficult to manufacture the feed rod because of evaporation of the elements such as F. As grown crystals had a black color and the length of 50~60mm, the diameter of 5~6mm. X-ray powder diffraction pattern indicated that the composition of the feed rod was right to the Tourmaline composition. By FT-IR spectra, the state of bonding of each element was charaterized.

• Bulletin of the Korean Chemical Society
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• v.30 no.6
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• pp.1285-1292
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• 2009

Large single crystals of zeolite, |$Na_{75}$|[$Si_{117}Al_{75}O_{384}$]-FAU (Na-Y, Si/Al = 1.56), were synthesized from gels with composition of 3.58Si$O_2$ : 2.08NaAl$O_2$ : 7.59NaOH : 455$H_2$O : 5.06TEA : 2.23TCl. One of these, a colorless single-crystal was ion exchanged by allowing aqueous 0.02 M CsOH to flow past the crystal at 293 K for 3 days, followed by dehydration at 673 K and 1 ${\times}\;10^{-6}$ Torr for 2 days. The crystal structure of fully dehydrated partially $Cs^+$-exchanged zeolite Y, |$Cs_{45}Na_{30}$|[$Si_{117}Al_{75}O_{384}$]-FAU per unit cell (a = 24.9080(10) $\AA$) was determined by single-crystal X-ray diffraction technique in the cubic space group Fd $\overline{3}$ m at 294(1) K. The structure was refined using all intensities to the final error indices (using only the 877 reflections with $F_o\;>\;4{\sigma}(F_o))\;R_1$ = 0.0966 (Based on F) and $R_2\;=\;0.2641\;(Based\;on\;F^2$). About forty-five $Cs^+$ ions per unit cell are found at six different crystallographic sites. The 2 $Cs^+$ ions occupied at site I, at the centers of double 6-ring (D6Rs, Cs-O = 2.774(10) $\AA$ and O-Cs-O = 88.9(3) and 91.1(3)$^o$). Two $Cs^+$ ions are found at site I’ in the sodalite cavity; the $Cs^+$ ions were recessed 2.05 $\AA$ into the sodalite cavity from their 3-oxygen plane (Cs-O = 3.05(3) $\AA$ and O-Cs-O = 77.4(13)$^o$). Site-II’ positions (opposite single 6-rings in the sodalite cage) are occupied by 7 $Cs^+$ ions, each of which extends 2.04 $\AA$ into the sodalite cage from its 3-oxygen plane (Cs-O = 3.067(11) $\AA$ and O-Cs-O = 80.1(3)$^o$). The 26 $Cs^+$ ions are nearly three-quarters filled at site II in the supercage, being recessed 2.34 $\AA$ into the supercage (Cs-O = 3.273(8) $\AA$ and O-Cs-O = 74.3(3)$^o$). The 4 $Cs^+$ ions are found at site III deep in the supercage (Cs-O = 3.321(19) and 3.08(3) $\AA$), and 4 $Cs^+$ ions at another site III’ (Cs-O = 2.87(4) and 3.38(4) $\AA$). About 30 $Na^+$ ions per unit cell are found at one crystallographic site; The $Na^+$ ions are located at site I’ in the sodalite cavity opposite double 6-rings (Na-O = 2.578(11) $\AA$ and O-Na-O = 97.8(4)$^o$).

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.281-282
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• 2014

본 연구는 공정시간에 따른 전해 플라즈마 공정(Electrolytic Plasma Processing, EPP) 공정에 의해 형성된 산화 코팅층의 특성 변화를 알아보고자 한다. 실험에 사용되는 전해용액은 $Na_2SiO_3$(12g/l) + $Na_2SiF_6$(0.3g/l)+NaOH(3g/l) 기본용액에 다양한 농도의 NaOH(0-5g/l) 첨가한 전해용액을 사용하였다. AZ61 마그네슘 합금을 모재($22{\Phi}{\times}10mm$)로 사용하였으며 실험은 5분-60분 동안 진행되었다. 공정시간에 변화에 따른 EPP 코팅층 특성을 측정한 결과 공정시간이 증가함에 따라 코팅층 표면의 기공 크기가 커지고 코팅층 내에 기공수가 즐어드는 것을 확인하였다. 또한 XRD 분석을 통하여 형성된 코팅층에서 MgO, Mg2SiO4 상이 나타난 것을 확인할 수 있었다.(No. 2011-0030058),(2012H1B8A2026212)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.274-274
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• 2007

LTCC 소재로 응용을 위해 Mg-Si-O계 세라믹스에 glass frit을 첨가하여 소결 및 마이크로파 유전특성에 관한 연구를 진행하였다. $Mg_2SiO_4$를 기본조성으로 하고 $B_2O_3-ZnO-Na_2O-SiO_2-Al_2O_3$계 glass를 20~40wt%로 첨가하여 $900^{\circ}C$에서 1시간 소결하였을 때 glass 함량이 증가함에 따라 밀도$(g/cm^3)$ 및 유전율$(\varepsilon_r)$은 증가하였고 품질계수$(Q{\times}f_0)$ 값은 감소하는 경향을 보였다. $900^{\circ}C$에서 1시간 소결한 소결체의 유전특성은 유전율 $(\varepsilon_r)$ = 6.5, 품질계수 $(Q{\times}f_0)$ = 4,000(GHz), 온도계수 $({\tau}_f)={\pm}10ppm/^{\circ}C$로 우수한 특성을 확인하였다. 그리고 Glass Milling 효과에 따른 glass-ceramics 소결체의 미세구조, 마이크로파 유전특성을 비교 고찰하였다.

• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.615-619
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• 2019

Various fluorides, i.e., CaF₂, Na₃AlF₆, K₂SiF₆, MnF₃, MgF₂, were added to the flux cored wire, and their effects on the oxygen content of the weld metal were investigated. The investigation showed that the oxygen content of weld metal was not influenced by the type of metallic elements in the fluoride; rather, it was influenced by the stability of the arc during welding. While the wire containing MgF₂ showed the most stable arc and the least amount of oxygen in the weld metal, the wire containing MnF₃ showed the least stable arc and the greatest amount of oxygen. Since the deoxidation of the weld metal was not affected by the deoxidation elements, such as Ca and Mg, it was possible to predict the oxygen content of the weld metal by the equilibrium Si-Mn deoxidation thermodynamic model.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.251-258
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• 2020

Single crystal of fully dehydrated and partially Ca²⁺-exchanged zeolites A (|Ca₄Na₄|[Si₁₂Al₁₂O₄₈]-LTA) was brought into contact with Se in fine pyrex capillary at 523 K for 5 days. Crystal structure of Se-sorbed |Ca₄Na₄|[Si₁₂Al₁₂O₄₈]-LTA has been determined by single-crystal X-ray diffraction techniques at 294 K in the cubic space group $Pm{\bar{3}}m$ (a = 12.2787(13) Å). The crystal structure of yellow |Ca₄Na₄Se₄|[Si₁₂Al₁₂O₄₈]-LTA has been refined to the final error indices of R₁/wR₂ = 0.0960/0.3483 with 327 reflections for which F_o > 4s(F_o). In this structure, 4 Na⁺ and 4 Ca²⁺ ions fill every 6-ring site: These ions are all found at three crystallographic positions, on 3-fold axes equipoints of opposite 6-rings. Selenium atoms are found at three crystallographically distinct positions: 2 Se atoms per unit cell at Se(1) are located opposite 6-rings in the sodalite cavity (Se(1)-Na(1) = 2.53(5) Å) and 1 at Se(2) opposite 4-rings (Se(2)-O(1) = 2.76(10) Å) and 1 at Se(3) opposite 6-rings in the large cavity (Se(3)-Na(1) = 2.48(5) Å). Two molecular of Se₂ (Se(1)-Se(1) = 2.37(7) or 2.90(8) Å and Se(2)-Se(3) = 2.91(5) ) Å) are found in all sodalite cavity and large cavity. Other clusters such as Se₄ and Se₈ could be existed in large cavity. The inter-selenium distances turned out to be longer that of gases Se₂ molecule.