• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.178-180
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• 2000

제올라이트의 결정성장은 유도기와 결정성장기 안정화기의 3단계로 진행한다 이러한 제올라이트의 결정성장 기구를 이해하고 결정의 성장기를 계속적으로 연장함으로서 조대한 NaX 제올라이트 결정의 성장을 유도하였으며, 선형결정성장속도에 대하여 고찰하였다. NaX 제올라이트의 수열합성 과정 중 결정성장기에 일정하게 3일 간격으로 반응용액내의 액상을 분리하고 반응겔을 보충하여 제올라이트의 합성 반응이 안정화기로 진행하는 것을 억제하고 결정 성장기를 연장하여 30㎛ 이상의 NaX 제올라이트 결정을 얻었다.

• Journal of the Mineralogical Society of Korea
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• v.23 no.1
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• pp.51-61
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• 2010

Ettringite $(Ca_6[Al(OH)_6]_2(SO_4)_3{\cdot}26H_2O)$ is a sulfate mineral that shows a complicate property in concrete. It is often called as "a cancer of concrete" because secondary ettringite formation in hardened concrete often cause expansion and cracking of concrete due to its expansive crystal structure. In the present study, we tested the possibility for crystal growth inhibition of secondary ettringite by crystallization inhibitors that are commercially used for scaling inhibitors in Korea. For the test, we developed a method of ettringite solution synthesis. Three types of crystallization inhibitors were selected and examined the effects On ettringite growth inhibition. The experimental results of ettringite solution synthesis indicated that ettringite was successfully synthesized under condition that the mass balance between calcium hydroxide saturated solution and aluminum sulfate solution was attained. Monosulfate and semisulfate were synthesized when the ratio of $Ca^{2+}$ ions to ${SO_4}^{2+}$ ions was increased. The induction time of ettringite crystallization was less than 2 min. and crystallization was almost completed within an hour. The experimental results of ettringite crystallization inhibition showed that organic PBCT (2-Phosphonobutane-1,2,4-Tricarboxylic Acid) and inorganic SHMP (Sodium Hexametaphosphate) were relatively less effective on ettringite crystallization inhibition under experimental conditions. However, organic HEDP (1-Hydoxyethylidene-1,1-Diphosphonic Acid) effectively prevented ettringite growth with producing amorphous gel phase materials up to inhibitor concentration 0.1 vol.% of aluminum sulfate solution.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.18-28
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• 1998

A laboratory experiment was made of a control of temperature oscillation in Czochralski convection. Numerical computation was also made to delineate the control of temperature oscillation. The suppression of temperature oscillation was achieved by varying the rotation rate of crystal rod ($\Omega=\Omega_0(1+A sin 2{\pi}ft/t_p)$), where A denotes the amplitude of rotation rate and f the frequency factor. Based on the inherent dimesionless time period of temperature oscillation ($t_p$), the suppression rate of temperature oscillation was characterized by the mixed convection parameter ($0.217{\leq}Ra/PrRe^2{\leq}1.658$). The optimal values of A and f were also scrutinized. To understand the suppression mechanism of temperature oscillation, the controls of isotherm($\theta$) and equi-vorticity($\omega$) were investigated.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.139-139
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• 2016

반도체 다마신배선용 도금용 구리도금첨가제는 대표적으로 accelerator, suppressor 및 leveler 첨가제를 사용하여 다마신 패턴을 채우고 평탄화를 시킬 수 있다. Si 반도체 공정기술에 기반한 정확한 구조분석을 통해 각각의 첨가제의 기능이 비교적 체계적으로 연구되었으며, 최근에는 유속영향을 많이 받는 것으로 알려진 leveler 첨가제에 대한 연구가 활발히 진행되고 있다. 본 연구는 대표적 leveler 첨가제의 하나인 Janus Green B(JGB, $C_{30}H_{31}ClN_6$)를 0 ~ 1 mM을 첨가하여 Si 기판위에 증착된 Cu 씨드층 상의 도금후 표면상태 및 불순물의 농도를 분석하고, 이 박막층들의 결정립 성장 경향성을 electron backscattered diffraction(EBSD) 분석을 통해 진행하였다. C, H, N 등의 불순물이 JGB 농도와 선형적 관계를 가지고 증가하는 것을 알 수 있었으며, S와 O의 불순물도 JGB 농도 증가에 따라 증가하는 것을 알 수 있었다. 또한 0.1 mM 첨가한 경우에 60% 정도 결정립 성장이 진행된 것을 알 수 있었으며, 0.2 mM을 넣은 경우에는 결정립 성장이 일어나지 않은 것을 알 수 있었다. 흥미로운 점은 4 point probe를 통한 면저항 측정을 통해 EBSD를 통한 결정립성장이 관찰되지 않은 0.2 mM JGB를 첨가한 경우에 대해서도 면저항의 감소가 관찰되며, 오히려 JGB 농도가 높을수록 이러한 면저항의 감소가 빠르게 시작되는 것을 관찰할 수 있었다. 이는 JGB 농도 증가에 따라 박막층의 불순물의 농도가 증가하고 막내에 존재하는 불순물의 농도가 증가하면 내부응력장이 커짐으로 인해 더욱 빠른 속도로 불순물의 재배치가 일어난 것으로 보인다. 이러한 불순물이 결정립계면에 편석되는 경우에 pinning을 통해 결정립계면의 이동을 저하시킬 수 있으므로 결정립의 성장 억제가 가능해진 것으로 판단된다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.536-547
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• 1997

For various angular velocities of crucible and crystal, the characteristics of melt flows, temperatures and concentrations of oxygen are numerically studied in the Czochralski furnace with a uniform axial magnetic field. Buoyancy effect due to the heating of crucible wall and thermocapillary effect due to the temperature gradient at the free surface, can be differentiably suppressed by the centrifugal forces due to the rotations of the crucible and crystal. The most important factor which yields the centrifugal forces is the rotation velocity of the crucible, that influences the fields of velocities, temperatures and concentrations. In the case that the crucible rotation velocity is not high, the rotations of the crystal gives rise to the centrifugal forces effectively.

• Korean Journal of Crystallography
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• v.3 no.1
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• pp.23-30
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• 1992

a-SiC crystals were grown on the (001) plane of a-SiC seed crystals by sublimation method to find effects of pressure-reduction rate of the crystal growth furnace own the growth rate and orientstion of grown SiC crystals. Pressure-reduction rate at the initial growth stage affected the crystallinity of grown SiC crystals. In case of high pressure-reduction rate, growth rate was high and 3csic polycrystalline was grown on the seed. On the other hand, low pressure-reduction rate caused the growth rate to be slow and 6H-SiC single crystal was grown on the seed. However, even after growing SiC for 2 hours under the condition in which.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.255-262
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• 1998

This study investigated the crystallization behaviour of sealing amorphous material heat-treated by conventional and microwave heating source. From X-ray diffraction and SEM analyses, it was shown that microwave heat-treated sample had well-grown $PbTiO_3$crystals and the high degree of crystallinity inspite of its heat-treated condition of shorten time and lower temperature as compared with a conventionally heat-treated sample. It was assumed that microwaves inhibit the nucleation of $PbTiO_3$crystal in nucleation stage, but promote the growth of $PbTiO_3$crystal above the critical size of crystal due to enhanced diffusion effect within the sample.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.25-32
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• 2009

The glass-ceramics composed of coal bottom ash produced from a thermal power plant, $Na_{2}O$ and $Li_{2}O$ as a flux agent and $TiO_2$ as a nucleation agent were fabricated and its microstructures were analyzed. The nepheline was a major crystal phase in the glass-ceramics fabricated and its amount increased with $TiO_2$ addition. The glass-ceramics without $TiO_2$ addition had the thick surface crystals induced by a surface-crystallization mechanism and no crystal in the interior matrix. The surface crystallization, however, was restrained and the interior matrix was completely crystallized showing dendrite shape spread with fine particles < $1{\mu}m$ when added with $TiO_2$ above 4 wt%. For the glass-ceramics containing 6 wt% $TiO_2$, the $5{\mu}m$-long dendrite crystal; were interlocked each other which could suppress the crack propagation effectively at the external loading applied.

• Korean Journal of Crystallography
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• v.10 no.1
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• pp.83-87
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• 1999

부유대용융법에 의하여 전이금속, 희토류금속, 및 3A족 금속이온의 종류와 농도를 조절하면서 Rutile 단결정을 성장하였으며, 결정결함과 1.55 ㎛에서의 광 투과도에 미치는 각 불순이온의 영향을 조사하였다. 주입된 불순이온 중에서 양호한 결정형을 나타내는 이온은 V5+, Fe3+, Al3+, Zr4+, Ga3+, Sc3+이었으며, Al3+, Zr4+, Sc3+ 이온은 우수한 투과도를 나타내었다. 성장된 결정 중에서 가장 양호한 결정형을 제공하고, 산소결핍 및 low-angle grain boundaries의 형성을 최대로 억제하며, 양호한 투과도를 나타낸 우수한 품질의 Rutile 단결정은 TiO2 99.4 at%-Al2O3 0.6 at%로 평가되었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.2
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• pp.23-33
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• 1991

Mn - Zn Ferrite has the natural characteristics of incongruent melting and the zinc oxide evaporation while the crystal is being grown. As a result of these, it comes into existence to be a non-uniform distribution of cations along the crystal growth axis and also Pt particles are usually precipitated into the crystals in Bridgman method since the melt zone is maintained for a long time in the crucible. These have bad effects on the magnetic properties of ferrites. But, to overcome these faults and then acquire the better single crystals. new modified growth method was developed and the growth factors were investigated as following: melt height in the crucible, surface tension and density of melt, the behavior of melt at interface, the shapes of crucible and solid -liquid interface, powder feeding rate, and the crystal growing speed. In additon, when we analyzed the compositional fluctuations of grown crystals, they were supressed within 1.5 mol% $Fe_20_3$, 2 mol% MnO, ZnO respectively with comparing to initial composition of crystal and the microstructures of crystals on the(110) plane were observed by optical microscope through the chemical etching technique and the magnetic properties were determined.