• Title/Summary/Keyword: Degree of crystallization

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Low temperature solid phase crystallization of amorphous silicon thin film by crystalline activation

  • Kim, Hyung-Taek;Kim, Young-Kwan
    • Journal of Korean Vacuum Science & Technology
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    • v.2 no.2
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    • pp.97-100
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    • 1998
  • We have investigated the effects of crystalline activation on solid phase crystallization (SPC) of amorphous silicon (a-Si) thin films. Wet blasting and self ion implantation were employed as the activation treatments to induce macro or micro crystalline damages on deposited a-Si films. Low temperature and larger grain crystallization were obtained by the applied two-step activation. High degree of crystallinity was also observed on both furnace and rapid SPC. crystalline activations showed the promotion of nucleation on the activated regions and the retardation of growth in an amorphous matrix in SPC. The observed behavior of two-step SPC was strongly dependent on the applied activation and annealing processes. It was also found that the diversified effects by macro and micro activations on the SPC were virtually diminished as the annealing temperature increased.

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Crystallization of Mesoporous Tin Oxide Prepared by Anodic Oxidation

  • Kim, Eun-Ji;Shin, Heon-Cheol
    • Journal of Electrochemical Science and Technology
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    • v.8 no.1
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    • pp.69-76
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    • 2017
  • Crystallization of one-dimensional porous tin oxide during the anodic oxidation of tin at ambient temperatures is reported. Remarkable crystallinity is achieved when a substrate with a high elastic modulus (e.g., silicon) is used and the tin coating on it is very thin. It is suggested that the compressive stress applied to the anodic tin oxide during the anodization process is the key factor affecting the degree of crystallinity. The measured value of the stress generated during anodization matches well with the range of the most favorable theoretical pressure (stress) for crystallization.

Crystallization and Transparency of $Li_2O$.$2SiO_2$ Glass-Ceramics ($Li_2O$.$2SiO_2$. 유리의 결정화와 투광성에 관한 연구)

  • 최병현;안재환;지응업
    • Journal of the Korean Ceramic Society
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    • v.27 no.4
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    • pp.521-528
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    • 1990
  • Li2O.2SiO2 glass-ceramics were made from the melt by the nucleation and growth treatment. The optimum nucleation temperature and time were determined from DTA curves of as-quenched and thermally treated glasses, and found to be 44$0^{\circ}C$ and 3hrs. The optical microscopic technique was also used to support this result. The volume fractions of crystals present in the partially crystallized specimens were measured using the optical microscopy and the amorphous X-ray scattering methods. The degree of crystallization increased with increasing the crystallization temperature and time. The crystalline phase identified by X-ray diffraction was lithium disilicate. As the crystallinity increased up to 95%, the transmittance of glass-ceramics was decreased linearly. It was also found that for the same heat treatment condition (575$^{\circ}C$, 30min), a thicker specimen showed higher transmittance, presumably due to less crystallinity.

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Computer simulation of electric field distribution in FALC process (FALC 공정에서의 전계 분포 전산모사)

  • 정찬엽;최덕균;정용재
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.13 no.2
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    • pp.93-97
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    • 2003
  • The crystallization behavior of amorphous silicon is affected by direction and intensity of electric field in FALC(Field-Aided Lateral Crystallization). Electric field was calculated in a simplified model using conductivity data of Mo, a-Si, $SiO_2$and boundary conditions for electric potential at the electrodes. The magnitude of electric field intensity in each corner of cathode was much larger than that in the center of patterns, and the electric field direction was 50~60 degree outside to cathode. And electric field intensity at a relatively small pattern was larger than that of a large pattern.

Study on crystallization behavior of an ethylene-polypropylene copolymer based encapsulant for photovoltaic application (태양전지 봉지재용 에틸렌-프로펠렌 공중합체의 결정화 거동에 관한 연구)

  • Son, Younggon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.12
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    • pp.737-742
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    • 2016
  • We prepared five different ethylene-propylene copolymers (EPCs) for use as the encapsulant of a photovoltaic module. All of the polymers were of commercial grade from ExxonMobile company and had different ethylene/propylene compositions. The crystallization behaviors and crystal structures of the polymers were analyzed by differential scanning calorimetry and wide angle X-ray scattering diffractometry, respectively. We observed the general trend that the degree of crystallization, density and glass transition temperature of the EPCs decreased with increasing ethylene content. However, an unexpected result was also observed: the EPC with the highest ethylene content (22.2 mol. %) showed the highest melting temperature. As a result, the EPC with 22.2 mol. % of ethylene shows the highest light transmittance, due to its having the lowest degree of crystallization and highest thermal creep resistance. This abnormal result is attributed to the blocky structure prepared by ExxonMobile's special catalyst technology. It was also observed that new additional melting peaks appeared as the crystallization time increased. Using wide angle X-ray scattering diffractometry, it was confirmed that these additional peaks originated from the formation of a new crystal structure caused by annealing.

Study on the glass-ceramics containing coal bottom ashes fabricated by 2-stages heat treatment method (2단계 열처리법으로 제조된 석탄바닥재가 주성분인 결정화 유리에 관한 연구)

  • Jo, Si-Nae;Kang, Seung-Gu
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.20 no.6
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    • pp.272-277
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    • 2010
  • The glass-ceramics containing bottom ash (B/A) which was a by-produced from an electrical power plant was fabricated and its crystalline phase, microstructure and mechanical properties were analyzed. At first, the glass was fabricated by adding modifier oxide $Li_2O$ to lower the melting temperature of coal bottom ash. The glass obtained was heat-treated by using a 2-stage process to crystallize, that is to say, to increase the degree of crystallization in the glass-ceramics, the first heat treatment for nucleation was performed followed by the secondary one for the growth of nucleates. The main crystalline phase formed in the glass-ceramics was ${\beta}$-spodumene and the secondary phase was $L_2SiO_3$. It was recognized that the degree of crystallization of glass-ceramics was increased with a holding time of the secondary heat treatment stage. In the case of the specimens hold up to 3 hour, the crystallization was not completed and the microstructures and morphologies of crystalline phase were not uniform. In the specimens of holding time over 9 hours, the cracks were generated inside of it, so its compressive strength would decrease due them. In conclusion, it was able to obtain the optimum condition to fabriate the glass-ceramics having the properties of high crystallization degree, uniform microstructures and morphologies and the high mechanical strength.

Crystallization of Benzene from Benzene-Cyclohexane Mixtures by Layer Melt Crystallization - Phenomena of Impurity Inclusion in Crystal - (경막형 용융결정화에 의한 벤젠-사이클로헥산 혼합물로부터 벤젠의 결정화-결정의 불순물 내포현상-)

  • Kim, Kwang-Joo;Lee, Jung-Min;Ryu, Seung-Kon
    • Applied Chemistry for Engineering
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    • v.8 no.3
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    • pp.389-394
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    • 1997
  • The distribution of impurity included in benzene layer crystal was explored in layer crystallization of cyclohexane and benzene mixtures. The influence of crystal growth rate on crystal purity was investigated. All experimental results for bezene-cyclohexane system obtained in layer crystallizer have been evaluated with the criterion of Wintermantel. The purity of crystal decreases with increasing degree of subcooling, decreasing feed concentration and increasing crystal growth rate. The crystal growth rate was a key parameter to determine the inclusion of impurity in crystals. The results obtained from runs performed at increasing crystallization time(i.e. crystal thickness) have clearly shown that migration of inclusions within crystal layer to the melt, leading to the removal of impurity occurs. The diffusion of impurity which takes place during the crystallization from the beginning, enhances a further purification of the crystal layer if that underwent a thermal gradient after growth of the layer crystal stops.

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Study on Dyeing Properties of Nylon 66 Nano Fiber (1) -Levelling Type Acid Dyes- (나일론 66 나노섬유의 염색성에 관한 연구(1) -균염성 산성염료-)

  • 이권선;이범수;박영환;김성동;김용민;오명준;정성훈
    • Textile Coloration and Finishing
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    • v.16 no.4
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    • pp.1-9
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    • 2004
  • In recent, development of nano fiber has been one of the most active subjects in the world. Nano fiber is defined as a ultra fine yarn with a diameter unit of $10-100\times10^{-9}meter$, which is possible to be produced by an electro-spinning technology. In this study, physical characteristics and dyeing properties of nylon 66 nano fiber were investigated. Nylon 66 nano fiber was dyed with levelling type acid dyes. X-ray diffraction method and DSC analysis were used for the measurement of the degree of crystallization. Analysis of amino end groups was also performed in order to examine a relationship between number of amino groups and its dyeing property as well as water absorption behavior. The maximum exhaustion % of dyes and dyeing rate under various dyeing conditions, such as dyeing temperature and pH in dye bath, along with build-up properties for 2 acid dyes were evaluated. It was found that the degree of crystallization of nano fiber was smaller than that of regular fiber, and amino end groups of nano fiber were less than regular fiber. Half dyeing time of nano fiber was shorter than regular fiber because of the bigger specific surface area. Effect of pH on exhaustion % was small in case of nano fiber. Exhaustion of nano fiber increased with higher concentration of dye.

Effect of Humidity on Polymorphic Transformation of Hydrous Aluminum Oxide (알루미나수화물(水和物)의 결정전이(結晶轉移)에 미치는 습도(濕度)의 영향(影響))

  • Rhee, Gye-Ju;Yoo, Byeong-Tae
    • Journal of Pharmaceutical Investigation
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    • v.13 no.1
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    • pp.1-9
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    • 1983
  • The effect of humidity on crystallization and polymorphic transformation of hydrous aluminum oxide under various humidity at $37^{\circ}$ was examined by means of X-ray diffraction, scanning electron micrograph, IR spectra and DTA. The humidity was an important factor influencing crystallization of hydrous aluminum oxide. The growth or crystal was strongly accelerated by humidity. The aging process is assumed that it is composed of two seperate steps, an increase of the diffraction around $36{\sim}42^{\circ}$, and an appearance and its development of the peak at $18{\sim}20^{\circ}$ of $2{\theta}$ value. The former is considered to be nucleation and the latter correspond to the growth period on crystallization. The crystalline form of aging products was various depending on the degree of humidity, directly it leads to the eventual formation of bayerite in more than 72%, $b{\"{o}}hmite$ in 50% and resembled to Nordstandite in 0% relative humidity, respectively but once formed, it was mostly stable in each surroundings and does not transform to the other more stable form in solid state even after aging for five years. The mechanism responsible for aging is further polymerization process of six-membered rings by deprotonation-dehydration reaction in which positively charged polynuclear hydroxy aluminum complexes formed in the presence of moisture are joined at their edges by double hydroxide bridges.

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Crystallization Behavior and Electrical Properties of IZTO Thin Films Fabricated by Ion-Beam Sputtering (이온빔 스퍼터링으로 증착한 IZTO 박막의 결정화 거동과 전기적 특성 분석)

  • Park, Ji Woon;Bak, Yang Gyu;Lee, Hee Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.34 no.2
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    • pp.99-104
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    • 2021
  • Ion-beam sputtering (IBS) was used to deposit semiconducting IZTO (indium zinc tin oxide) thin films onto heavily-doped Si substrates using a sintered ceramic target with the nominal composition In0.4Zn0.5Sn0.1O1.5, which could work as a channel layer for oxide TFT (oxide thin film transistor) devices. The crystallization behavior and electrical properties were examined for the films in terms of deposition parameters, i.e. target tilt angle and substrate temperature during deposition. The thickness uniformity of the films were examined using a stylus profilometer. The observed difference in electrical properties was not related to the degree of crystallization but to the deposition temperature which affected charge carrier concentration (n), electrical resistivity (ρ), sheet resistance (Rs), and Hall mobility (μH) values of the films.