• 한국전기전자재료학회논문지
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• 제23권4호
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• pp.323-326
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• 2010

$(Zn_{1-x}Ca_x)_2SiO_4$:Mn phosphors doped with Ca were synthesized by solid state reaction method. $(Zn_{1-x}Ca_x)_2SiO_4$:Mn phosphors showed XRD patterns of Willemite structure. Also, $CaSiO_3$ structure and new peak near 610 nm in $(Zn_{1-x}Ca_x)_2SiO_4$:Mn with increasing value of x were observed from XRD and PL. The new peak near 610 nm in $(Zn_{1-x}Ca_x)_2SiO_4$:Mn with doping Ca was attributed to formation of $CaSiO_3$.

• 한국세라믹학회지
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• 제37권12호
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• pp.1178-1186
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• 2000

타일의 내마모성과 내산성을 향상시키기 위해 결정화유리가 최근에 새로운 유약 재료로서 소개되고 있다. 신 유약의 연구에 사용된 조성은 $Ca_2$ZrSi$_4$O$_{12}$ 상에 근접하는 CaO-ZrO$_2$-SiO$_2$계의 유리조성의 분말로, 마이크로파 가열 (2.45 GHz)에 의해서 900-120$0^{\circ}C$의 0-20분간 소성되어 평가되었다. 그 결과, 100$0^{\circ}C$ 이상에서 소성한 시편은 내부 결정화를 나타내었으며, 결정상은 미세(5$mu extrm{m}$)한 크기를 갖는 $Ca_2$ZrSi$_4$O$_{12}$가 주 결정상이며, $Ca_2$ZrSi$_4$O$_{12}$, CaSiO$_3$, SiO$_2$의 세 상이 나타났다. 소결체의 미세구조는 사용한 유리분말의 입도의 영향을 받았다. 미세분말 (<38$\mu\textrm{m}$)을 이용한 소결체의 조직이 조세분말 (45-150$\mu\textrm{m}$)의 경우보다 수축율면에서 높았으며 낮은 기공도를 갖는 미세구조를 가졌다. 마이크로파에 의한 유리분말의 소성은 1000-120$0^{\circ}C$ 구간에서 10분 이내 결정화가 완료되는 급속 가열 공정이었으며 CaO-ZrO$_2$-SiO$_2$계 결정화 유리 제조에 균일한 체적가열을 할 수 있었다.

• 한국세라믹학회지
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• 제29권9호
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• pp.729-738
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• 1992

The glass formation and structural change with the glass compositions were investigated in the CaO-P2O5-SiO2 system with less than 40 wt% of P2O5. The glass formation range was determined by XRD, SEM and EDS techniques for water quenched specimens. The structural analyses were made for binary CaO-SiO2 glasses and ternary CaO-P2O5-SiO2 glasses by using FT-IR and Raman spectroscopy. The glass formation was affected by CaO/SiO2 mole ratio, P2O5 content and primary crystalline phase. The stable glass formation range was found when the transformed CaO/SiO2 mole ratio (new factor derived from structural changes) was in the range of 0.72~1.15 with less than 10 mol% of P2O5. The structural analyses of CaO-SiO2 glasses indicated that as the CaO/SiO2 ratio was increased, the nonbridging oxygens in the structural unit of the glasses were increased. With addition of P2O5 to CaO-SiO2 glasses, the P2O5 enhanced the polymerization of [SiO4] tetrahedra unit in CaO-SiO2 glasses, which contained a large portion of nonbridging oxygen. The phosphate eliminated nonbridging oxygens from silicate species, forcing polymerization of silicate structures and produced in [PO4] monomer in glasses. When added P2O5 was kept constant, the structural change with various CaO/SiO2 ratio was very similar to that of CaO-SiO2 glasses.

• 한국세라믹학회지
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• 제31권5호
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• pp.505-512
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• 1994

It has been reported that a biocement obtained by mixing CaO-SiO2-P2O5 glass powder and ammonium phosphate solution has biocompatibility as well as high strength. However, the compositional dependence on its hardening and hydroxyapatite formation phenomena has not been studied. Therefore, the main objective of this work is to study the effects of P2O5, MgO in CaO-SiO2 system glass on the hardening and hydroxyapatite formation. When more than 50 mole% of CaO containing CaO-SiO2 glasses was reacted with ammonium phosphate solution, CaNH4PO4.H2O crystal was formed, but the glass with less than 50 mol% of CaO formed (NH4)2HPO4 and NH4H2PO4 crystals which are derived from ammonium phosphate solution without reacting with the glasses. As the amount of P2O5 in CaO-SiO2-P2O5 glass system was increased, the formation of CaNH4PO4.H2O crystal was enhanced. When those hardened samples were reacted with tris-buffer solution, hydroxyapatite was obtained only for the sample with CaNH4PO4.H2O. While the substitution of MgO for CaO decreased the formation of CaNH4PO4.H2O crystal. MgNH4PO4.H2O crystla was formed in high MgO containing glass, which did not react with tris-buffer solution.

• 한국재료학회지
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• 제13권9호
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• pp.572-580
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• 2003

Synthesizing behavior and microstructural evolution of $CaZrO_3$and $m-ZrO_2$in a thermal reaction process of $ZrSiO_4$-$xCaCO_3$mixtures, where x is 7 and 19, were investigated to determine the addition amount of CaO in CaO:$ZrO_2$:$SiO_2$ternary composition. CaZrO$_3$-Ca$_2$SiO$_4$precursor prepared by the mixture of $ZrSiO_4$and CaCO$_3$in aqueous suspending media was controlled to the acidic (pH=4.0) condition with HCI solution to enhance the thermal reaction. The addition amount of dispersant into the $ZrSiO_4$-$xCaCO_3$slip increased with increasing mole ratio of $CaCO_3$, which was associated with the viscosity of slip. Decarbonation reaction was activated with an increase of the addition amount of $CaCO_3$, showing different final temperatures in $ZrSiO_4$-$7CaCO_3$and $ZrSiO_4$-$19CaCO_3$mixtures as about 980 and 116$0^{\circ}C$, respectively, for finishing decarbonation reaction. The grain morphology was changed to spherical shape for all samples with an increase of sintering temperature. The grain size and phase composition of the synthesized composites depended on the mixture ratio of Zrsi04 and CacO3 powders, indicating that the main crystals were m-ZrO2 ($\leq$3 $\mu\textrm{m}$) and $CaZrO_3$ ($\leq$ 7 $\mu\textrm{m}$) in $ZrSiO_4$$>-7CaCO_3$and $ZrSiO_4$-$19CaCO_3$mixtures, respectively.

• 한국결정성장학회지
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• 제5권3호
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• pp.291-298
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• 1995

알루미나 고상소결체와 $CaMgSiO_4$간의 반응에 따른 반응상들의 성장 및 용해 거동을 $1600^{\circ}C$에서 열처리 시간을 변화하여 고찰하였다. 열처리시 알루미나는 $CaMgSiO_4$ 액상에 용융되어 중간에 반응상인 $CaO{\cdot}6Al_2O_3$와 최종 반응상인 $CaMgSiO_4$ 스피넬 형성이 관찰되었다. 중간상인$CaO{\cdot}6Al_2O_3$ 결정은 성장 모양과 용해 모양이 뚜렷하게 구분되었다.

• 한국세라믹학회지
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• 제30권4호
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• pp.289-298
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• 1993

Properties in terms of the variation of the glass compositions, which were density (p), molar volume(Vm), atom/ion packing density (Dp), refractive index (nD), transformation temperature (Tg), dilatometric softening point (Td), thermal expansion coefficient (α), Young's modulus (E), and knoop hardness (KHN) were investigated in CaO-SiO2 glasses and CaO-P2O5-SiO2 glasses containing less than 10mole% of P2O5. Those properties were measured by density measurement kit, Abbe refractometer, dilatometer, ultrasonic pulse echo equipment, and micro hardness tester. When CaO content was increased in CaO-SiO2 glasses, p, Dp, nD, Tg, Td, α, E and KHN were increased, while Vm was decreased. When P2O5 was added to the CaO-SiO2 glasses with constant CaO/SiO2 ratio as 1.07, p, Dp, nD, Tg, Td, α, E and KHN were decreased, while Vm was increased. When the amount of P2O5 in glasses was kept constant, the changes of the properties with variation of CaO content in the CaO-P2O5-SiO2 glasses were very similar to those of CaO-SiO2 glasses. These phenomena could be explained by the structural role of P2O5 in the CaO-P2O5-SiO2 glasses, which was polymerization of siicate structures and resulted in [PO4] monomer structure in glasses. Due to this structural characteristics, the bond strength and packing density were changed with compositions. Proportional relationships between 1) np and Dp, 2) Tg, Td, α and CaO content, 3) E and Vm-1, and 4) KHN and P2O5 content were evaluated in this investigation.

• 공업화학
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• 제4권2호
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• pp.291-299
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• 1993

생석회-규사-수계 및 시멘트 슬러지-규사-수계에서 1.13nm tobermorite를 수열합성하였다. 생석회-규사-수계의 경우 반응온도 $180^{\circ}C$, $CaO/SiO_2$의 몰비 0.4, 0.8에서 공히 양질의 tobermorite($5CaO{\cdot}6SiO_2{\cdot}5H_2O:C_5S_6H_5$)가 형성되었으나 $CaO/SiO_2$의 몰비 0.4일 때는 반응시간 6시간에서, 0.8일 때는 4시간에서 결정전이 현상이 관찰되었다. 그러나 시멘트 슬러지를 생석회 대신 전량 사용한 시멘트 슬러지-규사-수계는 동일한 몰비에서 반응시간 10시간 이내에 결정전이 현상이 나타나지 않았는데 이는 시멘트 슬러지로부터 용출되어 나온 알루미늄 이온의 지연작용으로 판단되며 생석회-규사-수+알루미늄계에서 확인되었다. 알루미늄 분말의 첨가량이 0.8에서 3.0%로 증가함에 따라 결정은 보다 넓고 평평하게 형성되었다. 또한 동일한 반응시간 내에서 재결정화 현상이 관찰되지 않았다.

• Transactions on Electrical and Electronic Materials
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• 제15권5호
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• pp.249-252
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• 2014

The aim of this work is to investigate the effect of $Ca_xSr_{2-x}$ and activator on the structural and luminescent properties of green-emitting $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ nano phosphor. Using urea as fuel and ammonium nitrate as oxidizer, $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ has been successfully synthesized, using a combustion method. The particles were found to be small, spherical and of round surface. SEM imagery showed that the phosphors particles are of nanosize. The $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ emission spectrum for 360 nm excitation showed a single band, with a peak at 490 nm, which is a green emission. The highest luminous intensity was at $1,000^{\circ}C$, which was obtained when the $Eu^{2+}$ content (y) was 0.05. The results support the application of $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ phosphor as a fluorescent material for ultraviolet light-emitting diodes (UV-LEDs). Characteristics of the synthesized $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ phosphor were investigated by means of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and photoluminescence (PL) detection.

• 자원리싸이클링
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• 제20권4호
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• pp.58-64
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• 2011

고온에서 PCB 처리를 통한 Au, Ag와 같은 귀금속뿐 아니라 Ni과 같은 주요 회유금속을 회수하기 위한 기초연구로서 CaO-$Al_2O_3$(-$SiO_2$) 및 CaO-$SiO_2$-$CaF_2$ 슬래그를 이용하여 Au, Ag, Ni의 회수거동올 관찰하였다. 슬래그 투입 없이 PCB만으로 용융실험을 수행한 결과 PCB는 거의 용융되지 않았으며, 이로부터 유도전류를 이용한 용융을 촉진할 뿐 아니라 유가금속의 회수를 위해서는 Cu와 갇은 적절한 base metal이 필요함을 확인하였다. 본 연구결과, PCB/Cu ratio는 1 이하가 바람직할 것으로 생각된다. CaO-$Al_2O_3$(-$SiO_2$) 및 CaO-$SiO_2$-$CaF_2$ 슬래그를 투입한 결과, $CaF_2$를 함유하는 fluorosilicate계 슬래그가 calcium aluminate계 슬래그보다 융점과 점도가 낮게 제어되었으며, 이로부터 Au, Ag, Ni의 높은 분배비를 얻을 수 있었다. 점도가 낮은 $CaF_2$ 함유 슬래그 적용 시 높은 유가금속 회수율은 슬래그 내에서 각 금속입자의 등속침강속도가 상승하기 때문인 것으로 평가되었다.