• Title/Summary/Keyword: Crystallization process

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The Effect of Crystallization Condition on the Crystallization Rate of Zeolite A (제올라이트 A의 결정화 속도에 대한 결정화 조건의 영향)

  • Chung, Kyeong-Hwan;Seo, Gon
    • Applied Chemistry for Engineering
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    • v.4 no.1
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    • pp.94-102
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    • 1993
  • The effects of temperature and of $Na_2O$ and $SiO_2$ contents on the crystallization of zeolite A were studied, by examining crystallization curves and particle size distributions of final products at various crystallization conditions. Crystallization process could be simulated adopting the assumptions of constant linear growth rate and equilibrium between amorphous solid phase and soluble species. Rate constants were determined by comparing the simulated crystallization curves with experimental data. Rate constant for linear growth increased with temperature and crystallization rate at different mole ratio of $Na_2O/H_2O$ correlated reasonably well with increase of soluble species. The rate constant of crystallization did not increase with increase in mole ratio of $Na_2O/H_2O$, but the rate of nuclei formation and the fraction of soluble species were enhanced. The rate constants for linear growth of zeolite A were determined as $0.07{\sim}0.24{\mu}m{\cdot}min^{-1}$ at these experimental conditions Apparent activation energy was estimated as $49kJ{\cdot}mol^{-1}$.

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A new crystallization method using a patterned $CeO_2$ seed layer on the plastic substrate

  • Shim, Myung-Suk;Kim, Do-Young;Seo, Chang-Ki;Yi, Jun-Sin;Park, Young-Soo
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.1007-1010
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    • 2004
  • We report crystallization of a-Si using XeCl excimer laser annealing [1] on the plastic substrate. We tried to obtain higher crystallinity as the effect of $CeO_2$ seed layer patterned. Also, we tried to control the direction of crystallization growth of silicon layer for lateral growth as the type of $CeO_2$ pattern. This crystallization method plays an important role in low temperature poly-Si (LTPS) [2] process and flexible display.

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A Study of Thermal Properties of LDPE-Nanoclay Composite Films

  • Bumbudsanpharoke, Nattinee;Ko, Seonghyuk
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.21 no.3
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    • pp.107-113
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    • 2015
  • This work focused on the study of thermal properties and kinetic behavior of LDPE-nanoclay composite films. The effect of nanoclay content (0.5, 1, 3, and 5 wt%) on thermal stability and crystallization characteristics of the nanocomposites were investigated by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The results from endothermic curve showed that the nanoclay played an important role in the crystallization of nanocomposites by acting as nucleating agent. From exothermic curve, there was a crystallization temperature shift which was attributed to crystallization process induced by nanoclay. The TGA results showed that the addition of nanoclay significantly increased the thermal stability of LDPE matrix, which was likely due to the characteristic of layered silicates/clays dispersed in LDPE matrix as well as the formation of multilayered carbonaceous-silicate char. A well-known Coats-Redfern method was used to evaluate the decomposition activation energy of nanocomposite. It was demonstrated that introducing of nanoclay to LDPE matrix escalated the activation energy of nanocomposite decomposition resulting in thermal stability improvement.

Crystallization of a-Si Induced by Ni-Si oxide source

  • Meng, Z.;Liu, Z.;Zhao, S.;Wu, C.;Wong, M.;Kwok, H.;Xiong, S.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.985-988
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    • 2008
  • Metal induced crystallization of a-Si with a source of Ni/Si oxide was studied. Its mechanism to induce crystallization was discussed. It was found that new source behaves an effect of self-released nickel and reducing nickel residua, so can provide a wider process tolerance; improve the uniformity and stability of TFTs.

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LTPS produced by JIC (Joule-heating Induced Crystallization) for AMOLED TFT backplanes

  • Hong, Won-Eui;Lee, Seog-Young;Chung, Jang-Kyun;Lee, Joo-Yeol;Ro, Jae-Sang;Kim, Dong-Hyun;Park, Seung-Ho;Kim, Cheol-Su;Lee, Won-Pil;Kim, Hye-Dong
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.378-381
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    • 2009
  • As a Joule-heat source, a conductive Mo layer was used to crystallize amorphous silicon for AMOLED backplanes. This Joule-heating induced crystallization (JIC) process could produce poly-Si having a grain size ranging from tens of nanometers to greater than several micrometers. Here, the blanket (single-shot whole-plane) crystallization could be achieved on the $2^{nd}$ and the $4^{th}$ generation glass substrate.

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Magnetic Properties and Crystallization of Co-pt Amorphous Metallic Alloys

  • Yoo, Chung-Sik;Lim, Sung-K.;Yoon, C.S.;Kim, C.K.
    • Journal of Magnetics
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    • v.8 no.3
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    • pp.113-117
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    • 2003
  • $Co_{78-x}Pt_xB_{10}Si_{12}$ alloys were produced using the melt-spin process in order to study the crystallization behavior and ensuing magnetic properties of the $Co_{78-x}Pt_xB_{10}Si_{12}$ (Co-Pt) amorphous alloys as a function of the Pt content. We showed that when $\chi$ $>$ 15 well below its stoichiometric composition, CoPt crystallized in the amorphous alloy, thus greatly altering the crystallized microstructure and magnetic properties during annealing. Below this composition, the main crystallization product was Co with Pt dissolved in its lattice. In spite of the nucleation of CoPt with high magnetic anisotropy, the highest coercivity was obtained when x was 15. It was also concluded that the Pt addition deteriorated the glass stability, triggering the devitrification at a progressively lower temperature.

Application of 532 nm YAG-Laser Annealing to Crystallization of Amorphous Si Thin Films Deposited on Glass Substrates

  • Lee, Jong-Won;So, Byung-Soo;Chung, Ha-Seung;Hwang, Jin-Ha
    • Korean Journal of Materials Research
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    • v.18 no.3
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    • pp.113-116
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    • 2008
  • A 532 nm Nd-YAG laser was applied to crystallize amorphous Si thin films in order to evaluate the applicability of a Nd-YAG laser to low-temperature polycrystalline Si technology. The irradiation of a green laser was controlled during the crystallization of amorphous Si thin films deposited onto glass substrates in a sophisticated process. Raman spectroscopy and UV-Visible spectrophotometry were employed to quantify the degree of crystallization in the Si thin films in terms of its optical transmission and vibrational characteristics. The effectiveness of the Nd-YAG laser is suggested as a feasible alternative that is capable of crystallizing the amorphous Si thin films.

A study of crystallization of a-Si:H using a-Si:H/Cd interface layer (A-Si:H/Cd 계면층을 이용한 a-Si:H의 결정화 연구)

  • 김도영;최유신;임동건;김홍우;이수홍;이준신
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1997.11a
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    • pp.529-532
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    • 1997
  • We studied the crystallization of a-Si:H thin film. Multi-crystallized Si films are preferred in many applications such as FPD, solar cells, RAM, and integrated circuits. Because most of these applications require a low temperature process, we investigated a crystallization of a-Si:H using a Cd layer. A metal Cd shows an eutectic point at a temperature of 321$^{\circ}C$. This paper present Cd layer assisted crystallization of a-Si:H film for the various grain growth Parameters such as anneal temperature, Cd layer thickness, and anneal time

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Effects of operating conditions on the crystallization of lanthanum oxalate in semi-batch reactor (반회분식 반응기에서 란타늄 옥살레이트 결정화에 미치는 조업 조건의 영향)

  • 이종석;김운수;김우식;김용욱;김준수;장희동
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.6 no.3
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    • pp.449-462
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    • 1996
  • On the reaction crystallization of lanthanum oxalate effects of operation conditions of impeller speed, concentration and feed rate of reactant, and reaction temperature on the nucleation and growth of crystals were investigated experimentally. In general, at low supersation the analysis of crystallization processes is relatively clear. However, at high wupersaturation, which is usually applied in industrial crystallization, the processes are exhibited in much complication. In this study the lanthanum oxalate was crystallized by the reaction crystallization of high concentration of lanthanum chloride and oxalic acid in single-jet semi batch reactor. Agitation of solution and suspension in the reactor influenced to enhance the reaction process and crystal growth process which gave opposite effect on the crystallization of lanthanum oxalate. In our experiment since increase of impeller speed gave more influence on the reaction process rather than on the crystal growth process, the supersaturation concentration increased with increase of impeller speed, then resulted in decrease of mean crystal size. By the same effect of reactant concentration and feed rate, the decrease of mean crystall size of lanthanum oxalate was observed with increasing the reactant concentration and feed rate. In case of increasing reaction temperature, the mean crystal size increased. The morphology of lanthanum oxalate crystal was not changed within the variation ranges of the operation conditions which were applied in our experiment.

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Crystal growth of phospho-gypsum in Na2SO4 solution (황산나트륨 용액에서 인산부생석고의 결정성장 특성)

  • Lee, Gye-Seung;Lee, Jung-Mi;Song, Young-Jun;Shin, Kang-Ho;Kim, Youn-Che;Yoon, Si-Nae;Jang, Yoon-Ho;Lee, Sung-Riong
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.21 no.1
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    • pp.6-14
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    • 2011
  • The re-crystallization process for recovering granular crystalline gypsum from phospho-gypsum have proposed. The process consists of two stages; at the first stage, needle-like fine gypsum is recovered with under-product of 325 mesh wet screening after the speedy hydration of dehydrated phospho-gypsum, and at the second stage, granular crystalline gypsum is recovered with upper-product of 325 mesh wet screening after dehydration and re-crystallization of the needle-like fine gypsum in $Na_2SO_4$ solution. This paper is mainly focused on the influence of dehydration time, cooling speed of temperature and re-crystallization temperature on the recovery of granular crystalline gypsum. And the re-crystallization velocity of needle-like fine gypsum at room temperature and the variation of $Ca^{2+}$ concentration of gypsum slurry during over all re-crystallization process were also discussed.