• 대한환경공학회지
• /
• 제30권2호
• /
• pp.207-212
• /
• 2008

본 연구에서는 seed 물질을 첨가함으로써 struvite 결정핵의 생성 및 성장단계를 단축시키고자 하였다. 본 연구에서는 seed 물질의 성상(모래, 안트라사이트, struvite)별, 입자의 크기(44$\sim$63 $\mu$m, 63$\sim$88 $\mu$m, 88$\sim$114 $\mu$m)별, 교반조건($G{\cdot}t_d$)에 따라 결정핵의 생성속도론에 미치는 영향을 관찰하였다. 모래와 안트라사이트는 seeding 하지 않은 경우에 비하여 암모니아성 질소제거효율이 각각 9%, 11%로 향상되었으며, struvite로 seed한 경우는 암모니아성 질소제거효율은 20% 이상 향상되었다. Seeding에 따른 struvite 결정화 효율은 seed 입자의 비표면적과 밀접한 상관관계가 있다. Seed 물질입자의 비표면적이 클수록 struvite 핵생성 및 성장을 향상시켰다. 또한 struvite 결정화 반응시 동질의 seed 물질(struvite seeds)을 사용하여 2차 핵생성을 유도하면 struivte 결정의 핵생성 및 성장을 위한 $G{\cdot}t_d$값을 단축시킬 수 있는 것으로 나타났다. 본 연구에서 고려한 입자크기에 대해서는 seed 입자크기에 대한 영향은 확인되지 않았다. Struvite 결정핵 생성속도론에서 $G{\cdot}t_d$값은 매우 중요한 인자로써 작용하였다.

• 한국물환경학회지
• /
• 제26권4호
• /
• pp.664-672
• /
• 2010

This study was performed to evaluate the feasibility of industrial by-products such as converter slag, olivine, red mud and fly ash as a seed crystal of struvite crystallization for the removal of highly concentrated $NH_4-N$ and $PO_4-P$. In the kinetic experiments, more than 90% of $NH_4-N$ and $PO_4-P$ was eliminated by struvite crystallization within 30 minutes of reaction time. The pH range in meta-stable region of struvite crystallization was found to be pH 7.0~9.0 under the Mg:N:P=1:1:1 equi-molar condition with 100 mg/L of $NH_4-N$. Total removal efficiencies of $NH_4-N$ and $PO_4-P$ by both struvite precipitation and crystallization were increased with the increase of pH. Removal efficiencies of $NH_4-N$ and $PO_4-P$ were significantly enhanced by struvite crystallization using industrial by-products as a seed crystal compared with those by struvite precipitation without seed crystal. Red mud, converter slag, olivine and fly ash enhanced the removal efficiencies of $NH_4-N$ by 40.9%, 37.7%, 28.4% and 16.4%, respectively. Removal efficiencies of $PO_4-P$ for converter slag, red mud, fly ash, olivine were increased by 3.7 times, 2.6 times, 72.4% and 68.0%, respectively. Converter slag and red mud showed higher feasibility as a seed crystal than others for the removal of highly concentrated $NH_4-N$ and $PO_4-P$. In particular, converter slag might have a high capacity of phosphorus removal.

• 한국재료학회지
• /
• 제24권9호
• /
• pp.443-450
• /
• 2014

Amorphous (a-Si) films were epitaxially crystallized on a very thin large-grained poly-Si seed layer by a silicide-enhanced rapid thermal annealing (SERTA) process. The poly-Si seed layer contained a small amount of nickel silicide which can enhance crystallization of the upper layer of the a-Si film at lower temperature. A 5-nm thick poly-Si seed layer was then prepared by the crystallization of an a-Si film using the vapor-induced crystallization process in a $NiCl_2$ environment. After removing surface oxide on the seed layer, a 45-nm thick a-Si film was deposited on the poly-Si seed layer by hot-wire chemical vapor deposition at $200^{\circ}C$. The epitaxial crystallization of the top a-Si layer was performed by the rapid thermal annealing (RTA) process at $730^{\circ}C$ for 5 min in Ar as an ambient atmosphere. Considering the needle-like grains as well as the crystallization temperature of the top layer as produced by the SERTA process, it was thought that the top a-Si layer was epitaxially crystallized with the help of $NiSi_2$ precipitates that originated from the poly-Si seed layer. The crystallinity of the SERTA processed poly-Si thin films was better than the other crystallization process, due to the high-temperature RTA process. The Ni concentration in the poly-Si film fabricated by the SERTA process was reduced to $1{\times}10^{18}cm^{-3}$. The maximum field-effect mobility and substrate swing of the p-channel poly-Si thin-film transistors (TFTs) using the poly-Si film prepared by the SERTA process were $85cm^2/V{\cdot}s$ and 1.23 V/decade at $V_{ds}=-3V$, respectively. The off current was little increased under reverse bias from $1.0{\times}10^{-11}$ A. Our results showed that the SERTA process is a promising technology for high quality poly-Si film, which enables the fabrication of high mobility TFTs. In addition, it is expected that poly-Si TFTs with low leakage current can be fabricated with more precise experiments.

• 한국물환경학회지
• /
• 제21권1호
• /
• pp.59-65
• /
• 2005

A phosphate recovery system from artificial wastewater was developed using a completely mixed phosphorus crystallization reactor, in which powdered converter slag was used as a seeding crystal. In preliminary test, the optimal pH range for meta-stable hydroxyapatite crystallization for high phosphorus concentration was observed to be 6.0 to 7.0, which was different from the conventionally known pH range (8.0~9.5) for effective crystallization in relatively low phosphorus concentration less than 5 mg/L. The average phosphorus removal efficiency in a lab-scaled completely mixed crystallization system for artificial wastewater with about 100 mg/L of average $PO_4-P$ concentration was shown to be 60.9% for 40 days of lapsed time. XRD analysis exhibited that crystalline of hydroxyapatite formed on the surface of seed crystal, which was also observed in SEM analysis. In EDS mapping analysis, composition mole ratio (=Ca/P) of the crystalline was found to be 1.78, indicating the crystalline on the surface of seed crystal is likely to be hydroxyapatite. Particle size distribution analysis showed that average size of seed crystal increased from $28{\mu}m$ up to $50{\mu}m$, suggesting that phosphorus recycling from wastewater with high phosphorus concentration can be successfully obtained by using the phosphorus crystallization recovery system.

• 한국미생물·생명공학회지
• /
• 제9권1호
• /
• pp.1-6
• /
• 1981

5'-GMP.2Na를 결정화하기 위한 조건을 검토한 결과 첨가한 용매는 methanol을 사용하였고, 온도는 45$^{\circ}C$, 교반 속도는 160-200rpm으로 하는 것이 좋았다. 이를 Reynold수로 환산한 결과 25,000-32,000이었다. 그리고 결정 seed의 첨가가 결정화에 영향을 줌을 알 수 있었으며 seed 첨가는 methanol 농도가 7.5%에서 10%의 사이가 좋았고 결정의 최대회수의 methanol 농도는 70%이었다.

• 한국재료학회지
• /
• 제22권4호
• /
• pp.190-194
• /
• 2012

The formation of high-quality polycrystalline silicon (poly-Si) on relatively low cost substrate has been an important issue in the development of thin film solar cells. Poly-Si seed layers were fabricated by an inverse aluminum-induced crystallization (I-AIC) process and the properties of the resulting layer were characterized. The I-AIC process has an advantage of being able to continue the epitaxial growth without an Al layer removing process. An amorphous Si precursor layer was deposited on Corning glass substrates by RF magnetron sputtering system with Ar plasma. Then, Al thin film was deposited by thermal evaporation. An $SiO_2$ diffusion barrier layer was formed between Si and Al layers to control the surface orientation of seed layer. The crystallinity of the poly-Si seed layer was analyzed by Raman spectroscopy and x-ray diffraction (XRD). The grain size and orientation of the poly-Si seed layer were determined by electron back scattering diffraction (EBSD) method. The prepared poly-Si seed layer showed high volume fraction of crystalline Si and <100> orientation. The diffusion barrier layer and processing temperature significantly affected the grain size and orientation of the poly Si seed layer. The shorter oxidation time and lower processing temperature led to a better orientation of the poly-Si seed layer. This study presents the formation mechanism of a poly seed layer by inverse aluminum-induced crystallization.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
• /
• pp.1007-1010
• /
• 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.

• 한국결정성장학회지
• /
• 제12권4호
• /
• pp.190-195
• /
• 2002

NaX seed결정(10~20 $\mu$m)을 $3.5Na_2$O : $Al_2O $: $2.1SiO_2$ : $1000H_2$O 용액에 0.5~2.0g 첨가한 후 연속결정화법으로 50 $\mu$m의 균일한 결정을 성장시켰다. 연속결정화법에 의한 결정성장을 시험하기 위하여, 모액을 7일, 5일, 3일, 2일과 1일 간격으로 공급하였다. Seed 첨가의 결과는 첨가하지 않은 용액과 비교하여 보다 균일하고 큰 결정들을 얻었다. 합성용액에 seed의 첨가는 반응물과 물리적인 접촉 면적을 초래하여 합성 겔의 핵성장 없이 seed 결정의 결정성장을 확인할 수 있다.

• 한국세라믹학회지
• /
• 제36권10호
• /
• pp.1048-1055
• /
• 1999

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2010년도 춘계학술발표대회
• /
• pp.58.1-58.1
• /
• 2010

We have developed a novel crystallization process, where the crystallization temperature is lowered compared to the conventional RTA process and the metal contamination is lowered compared to the conventional VIC process. A very-thin a-Si film was deposited and crystallized at $550^{\circ}C$ for 3 h by the VIC process and then a thick a-Si film was deposited and crystallized by the RTA process at $680^{\circ}C$ for 5 min using the VIC poly-Si layer as a crystallization seed layer. The RTA crystallized temperature could be lowered up to $50^{\circ}C$, compared to RTA process alone. The poly-Si film appeared a needle-like growth front and relatively well-arranged (111) orientation. In addition, the Ni concentration in the poly-Si film was lowered to $3{\times}10^{17}\;cm^{-3}$ and that at the poly-Si/$SiO_2$ interface was lowered to $5{\times}10^{19}\;cm^{-3}$. The reduction in metal contamination could be greatly helpful to achieve a low leakage current in poly-Si TFT, which is the critical parameter for commercialization of AMOLED.