Crystal growth, optical and luminescence properties of Na₆Mo₁₁O₃₆ single crystal

Pandey, Indra Raj,Karki, Sujita,Kim, H.J.,Lee, M.H.,Kim, Y.D. Elsevier 2019 Journal of crystal growth Vol.512 No.-

<P><B>Abstract</B></P> <P>The inorganic material Na<SUB>6</SUB>Mo<SUB>11</SUB>O<SUB>36</SUB> was synthesized by solid-state reaction, and a single crystal of the compound was grown using the Czochralski technique. The crystal structure of the compound was confirmed by X-ray diffraction (XRD) analysis. The luminescence light yield and fluorescence decay time of the crystal were studied in a temperature range from room temperature to 10 K using a 280 nm light emitting diode (LED) source. The Na<SUB>6</SUB>Mo<SUB>11</SUB>O<SUB>36</SUB> crystal has no luminescence at room temperature, however, the luminescence intensity is enhanced at low temperatures. Transmittance spectrum measurement was performed to study the optical quality of the crystal. The luminescence light yield of the Na<SUB>6</SUB>Mo<SUB>11</SUB>O<SUB>36</SUB> was compared with that of a Li<SUB>2</SUB>MoO<SUB>4</SUB> crystal at different low temperatures. Because of the possibility of growing a single crystal of Na<SUB>6</SUB>Mo<SUB>11</SUB>O<SUB>36</SUB>, which has a significant luminescence light yield at 10 K and no heavy elements, this crystal can be a good candidate for a rare event search experiment searching for neutrinoless double beta (0νββ) decay at cryogenic temperatures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Single crystals of Na<SUB>6</SUB>Mo<SUB>11</SUB>O<SUB>36</SUB> is grown for first time. </LI> <LI> Powder XRD result of Na<SUB>2</SUB>Mo<SUB>4</SUB>O<SUB>13</SUB> and Na<SUB>6</SUB>Mo<SUB>11</SUB>O<SUB>36</SUB> compound shows that, both compound has almost the same phase. </LI> <LI> Luminescence properties of new Na<SUB>6</SUB>Mo<SUB>11</SUB>O<SUB>36</SUB> crystal is reported. </LI> <LI> The luminescence result of Na<SUB>6</SUB>Mo<SUB>11</SUB>O<SUB>36</SUB> at 10 K is compared with Li<SUB>2</SUB>MoO<SUB>4</SUB> crystal. </LI> <LI> At 10 K, luminescence light yield of Na<SUB>6</SUB>Mo<SUB>11</SUB>O<SUB>36</SUB> is almost double than Li<SUB>2</SUB>MoO<SUB>4</SUB> crystal. </LI> </UL> </P>

Anti-solvent crystallization of l-threonine in Taylor crystallizers and MSMPR crystallizer: Effect of fluid dynamic motions on crystal size, shape, and recovery

Lee, S.,Lee, C.H.,Kim, W.S. North-Holland Pub. Co 2017 Journal of crystal growth Vol.469 No.-

The influence of the fluid dynamic motions of a periodic Taylor vortex and random turbulent eddy on the anti-solvent crystallization of l-threonine was investigated. The Taylor vortex flow and random turbulent eddy flow were generated by the inner cylinder rotation in a Couette-Taylor (CT) crystallizer and the impeller agitation in a mixed-suspension mixed product removal (MSMPR) crystallizer, respectively. Furthermore, the circumferentially sinusoidal fluctuation of a Taylor vortex was induced in an elliptical Couette-Taylor (ECT) crystallizer . The periodic Taylor vortex flows in the CT and ECT crystallizers resulted in a smaller crystal size and higher crystal recovery ratio of l-threonine than the random turbulent flow in the MSMPR crystallizer due to induction of a higher supersaturation, resulting in a higher nucleation in the CT and ECT crystallizers than in the MSMPR crystallizer. Thus, the crystal size was reduced and the crystal recovery ratio enhanced when increasing the rotation/agitation speed and feed flow rate in the CT, ECT, and MSMPR crystallizers. When increasing the temperature, the crystal size and crystal recovery ratio were both increased due an enhanced mass transfer for crystal growth. The crystal morphology changes according to the fluid dynamic motion with various crystallization conditions were well correlated in terms of the supersaturation.

Seed Polarity Dependence of SiC SingleCrystal Growth by Using a Physical Vapor Transport Method

Jung-Gon Kim,Chang-Hyun Son,Jung-Woo Choi,Jung-Kyu Kim,Byoung-Chul Shin,Il-Soo Kim,S. Nishino,이원재,서정두,구갑렬 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.5

6H-SiC single crystal ingots grown by using the sublimation physical vapor transport (PVT) technique were prepared on two-seed crystals with opposite face polarities; then, SiC crystal wafers sliced from the SiC ingot were systematically investigated to find out the polarity dependence of the crystal quality. The growth rate of the 2-inch SiC crystal grown in this study was about 0.3 mm/hr. n-type 200 SiC single crystals exhibiting the polytype of 6H-SiC were successfully fabricated. The incorporation of nitrogen donors in the SiC crystals grown on the C-face seed crystal was shown to be higher than in SiC crystals grown on a Si-face crystal. When the SiC crystal ingot proceeded to grow, the SiC crystal region grown on the C-face seed crystal was enlarged compared to the SiC crystal region on the Si-face seed crystal; finally a SiC crystal having only a C-face was obtained. X- ray rocking curves and reciprocal space mappings (RSM) definitely revealed a better crystal quality for the SiC crystal grown on the C-face seed crystal than for the SiC crystal grown on the Si-face. 6H-SiC single crystal ingots grown by using the sublimation physical vapor transport (PVT) technique were prepared on two-seed crystals with opposite face polarities; then, SiC crystal wafers sliced from the SiC ingot were systematically investigated to find out the polarity dependence of the crystal quality. The growth rate of the 2-inch SiC crystal grown in this study was about 0.3 mm/hr. n-type 200 SiC single crystals exhibiting the polytype of 6H-SiC were successfully fabricated. The incorporation of nitrogen donors in the SiC crystals grown on the C-face seed crystal was shown to be higher than in SiC crystals grown on a Si-face crystal. When the SiC crystal ingot proceeded to grow, the SiC crystal region grown on the C-face seed crystal was enlarged compared to the SiC crystal region on the Si-face seed crystal; finally a SiC crystal having only a C-face was obtained. X- ray rocking curves and reciprocal space mappings (RSM) definitely revealed a better crystal quality for the SiC crystal grown on the C-face seed crystal than for the SiC crystal grown on the Si-face.

Growth and characterization of Na₂Mo₂O₇ crystal scintillators for rare event searches

Pandey, Indra Raj,Kim, H.J.,Kim, Y.D. Elsevier 2017 Journal of crystal growth Vol.480 No.-

<P><B>Abstract</B></P> <P>Disodium dimolybdate (Na<SUB>2</SUB>Mo<SUB>2</SUB>O<SUB>7</SUB>) crystals were grown using the Czochralski technique. The thermal characteristics of the compound were analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements. The crystal structure of the grown sample was confirmed using X-ray diffraction (XRD). Luminescence properties were measured at room and low temperatures, using a light emitting diode (LED) source. Very weak luminescence was observed at room temperature; however, the luminescence intensity was enhanced at low temperatures. The crystal’s transmittance spectrum was measured for estimating its optical quality and energy band gap. The grown crystal exhibited a luminescence light yield of 55% compared with CaMoO<SUB>4</SUB> crystals at 10 K, when excited by a 280-nm-wavelength LED source, but does not have the drawbacks of radioactive Ca isotopes. These results suggest that at cryogenic temperatures, Na<SUB>2</SUB>Mo<SUB>2</SUB>O<SUB>7</SUB> crystal scintillators are promising for the detection of dark matter and neutrinoless double beta decay of <SUP>100</SUP>Mo.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Single crystals of Na<SUB>2</SUB>Mo<SUB>2</SUB>O<SUB>7</SUB> was grown by Czochralski technique at first time. </LI> <LI> Scintillation properties of new Na<SUB>2</SUB>Mo<SUB>2</SUB>O<SUB>7</SUB> crystal scintillator was reported. </LI> <LI> The grown material was less hygroscopic than Li<SUB>2</SUB>MoO<SUB>4</SUB> single crystal. </LI> <LI> At 10 K, light yield of reported crystal was 55% as compared to reference CaMoO<SUB>4</SUB> crystal. </LI> <LI> This crystal was found promising candidate for 0ν2β decay and dark matter search at low temperature. </LI> </UL> </P>

R.W. 파스빈더와 크리스탈-이미지-파스빈더의 자전적 영화 < 13달인 어느 해 > (1978)를 중심으로-

김형래 ( Hyung Rae Kim ) 한양대학교 현대영화연구소 2016 현대영화연구 Vol.12 No.2

본 논문은 독일의 천재적인 영화감독 파스빈더의 영화 < 13달인 어느 해 > 를 분석한다. 기존에 파스빈더 영화에 대한 많은 연구가 있었지만, < 13달인 어느 해 >에 대한 연구는 독일에서뿐만 아니라 국내에서도 찾아보기 힘들었다. < 13달인 어느 해 >은 그의 영화 가운데 매우 난해한 것 중 하나이며 가장 비극적 내용을 가지고 있는 영화라고 할 수 있다. 이 영화가 난해한 것은 장 면의 구성과 배치, 즉 미장센의 독특한 구성 때문일 것이며, 영화가 비극적 인 것인 파스빈더 개인의 자전적 요소 때문일 것이다. 영화는 트랜스젠더인 주인공 에르빈/엘비라의 삶을 조명한다. 그/그녀는 전후세대로서 어린 시절 부모로부터 버림받고 수녀원에서 고아로 자란다. 나이가 들어 정육점에서 일하다 정육점 주인의 딸과 결혼하지만, 우연히 유태인 부동산업자 안톤 자이츠를 만나 사랑에 빠지고, 그의 사랑을 받기 위해 여자가 될 것을 결심하고 성전환 수술을 한다. 그러나 결국 그는 모두로부터 버림받는 존재가 되어 매 춘 행위를 하며 생활하다 최후에는 자살로 생을 마감한다. 이것은 파스빈더 와 그의 동성애 파트너인 아르민 마이어와의 관계를 연상시키는 자전적 내 용이다. 물론 영화는 한 인간의 비극적 이야기로만 이루어져 있지 않다. 영 화는 이 이야기를 통해 전후 독일의 정치, 경제적 상황을 암시하고 있다. 이 와 같이 영화는 멜로드라마를 바탕으로 하여 다양한 주제의식을 표출하고 있는 만큼 그 구성 또한 복잡할 수밖에 없다. 따라서 본고는 이와 같은 특성을 가지고 있는 < 13달인 어느 해 >를 들뢰즈의 『시네마 2』에서 제시한 결정체-이미지 개념을 이용해 분석하고 있다. 의미층위가 다층적인 이 영화를 분석하는 데 결정체-이미지가 적절한 도구가 될 수 있기 때문이다. 따라서 본고는 먼저 결정체-이미지가 무엇인지 상세하게 정의한 다음 영화를 분석한다. 들뢰즈는 네 가지 결정체-이미지의 상태를 분류하는데, 그것은 각각 완벽한 결정체, 틈과 균열의 결정체, 형성중인 결정 체, 해체되는 결정체이다. 본고의 분석 결과 < 13달인 어느 해 >는 완벽한 결 정체-이미지를 통해 보다 더 잘 이해 될 수 있음을 알게 되었다 of R.W.Fassbinder, using Gilles Deleuze’s concept of the crystal-image that he developed in his book Cinema 2: the time-images. This article aims to show that the life and death of the protagonist Erwin/Elvira in this film can be effectively explicated through the crystal-images, and evaluates the validity of Deleuze’s taxonomy of images for the practical analysis of films. Before analysing precisely the film images in In a Year with 13 Moons, the part I introduces the concept of the crystal-image. Deleuze first classifies the concept of crystal-images into three aspects or pairs: the actual/the virtual, the transparent/the opaque and the embryo/the milieu. He then classifies the crystal-image again into four states: Ophuls and the perfect crystal, Renoir and the cracked crystal, Fellini and the formation of the crystal and Visconti and the decomposing crystal. The part II identifies the various sorts of the crystal-images to interpret In a Year with 13 Moons. In this film it is the mirror images as a sort of the crystal-images that are predominant. It can be said that In a Year with 13 Moons is itself like a mirror, which reflects the painful lives of Erwin/Elvira, Fassbinder’s homosexual partner Armin Meyer and Fassbinder himself, set in the sociopolitical context of West Germany in the 1970s. A kind of a mirror chamber made of the multiple mirrors, or like a theater stage, where not only the lives of the actors and Fassbinder but also his contemporary milieu are reflected. The film reminds us of the perfect crystal-image described by Deleuze. As he says, in this perfect crystal are not a crack and no way to escape from the perfect crystalline circuit. As a result we can find that In a Year with 13 Moons is made of full of the crystal-images, especially the perfect crystal-images and that Deleuze’s taxonomy of images can be useful in understanding complex and experimental modern films like Fassbinder’s

법랑질표면에서 폴리아크릴산용액 농도와 황산이온 농도가 결정형성에 미치는 영향

김주형,이기수 대한치과교정학회 1998 대한치과교정학회지 Vol.28 No.5

교정장치의 직접부착을 위하여 일반적으로 사용되고 있는 산부식법의 대체가능 방법중 하나는 결정형성법이며, 폴리아크릴산과 황산이온은 결정형성액의 주요 물질로 알려져 왔다. 이 연구는 황산이온농도와 폴리아크릴산의 농도변화가 결정형성에 미치는 영향을 관찰하여 결정형성용액에 관한 기초자료를 획득하기 위하여 시행되었다. 분자량 5,000의 폴리아크릴산을 10%, 20%, 30% 및 40%의 용액으로 만들고, 각각의 용액에 황산이온 농도가 0.1M, 0.2M, 0.3M, 0.5M 및 1.0M이 포함되는 총 20가지의 실험용 결정형성용액을 제조하고, 이들을 법랑표면에 60초간 반응시킨 후, 주사전자현미경 사진을 촬영하여 결정 피복도, 결정 길이 및 결정형태 분포의 균일성을 평가하여 다음과 같은 결론을 얻었다. 1. 폴리아크릴산 용액은 법랑질 표면을 경미하게 부식시켰으며, 농도에 따른 부식효과의 차이는 없었다. 2. 폴리아크릴산의 농도는 결정형성에 적은 영향을 미쳤다. 특히 20% - 40%사이의 폴리아크릴산 용액은 결정형성에 영향을 미치지 않았다. 3. 황산이온 농도는 결정형성의 주요인자이다. 0.2M이상의 황산이온이 포함된 폴리아크릴산 용액에서 결정이 형성되었다. 4. 20%∼40% 폴리아크릴산 용액에 포함된 황산이온농도가 결정 피복도에 미치는 영향은 황산이온 농도가 어느한도까지 증가하면 결정 피복도도 증가하나 그 이상에서는 감소하는 경향으로 나타났다. 이 실험에서는 0.5M 황산이온이 포함된 실험용액이 가장 높은 결정 피복도를 나타냈으며, 최대의 결정 피복도를 나타내는 황산이온 농도는 0.5M, 혹은 0.5M에서 1.0M사이에 있을 것으로 추정되었다. 5. 폴리아크릴산 용액내의 황산이온 농도가 증가할수록 결정길이는 작아지는 경향을 보였다. 6. 폴리아크릴산 용액내의 황산이온 농도는 결정 형태의 분포에 영향을 미친다. 황산이온의 농도가 낮을수록 spherulitic형 배열의 결정형성이 증가하고, 황산이온농도가 증가하면 무정형 배열의 결정형성이 증가하는 경향을 보였다. 7. 이 연구에서 가장 양호한 실험용 결정형성용액은 0.5M 황산이온이 포함된 30% 폴리아크릴산 용액이었다. This study was designed to observe the effects of various concentration of polyacrylic acid containing different concentration of sulfate ion on the crystal formation on the enamel surface. Experimental crystal growth solutions were made of 10%, 20%, 30%, and 40% polyacrylic acid(molecular weight, 5,000)solutions which contacted for 60seconds with these solutions, washed for 15 seconds, dried, and then the crystal topography on the enamel surface was observed under the scanning election microscope. The crystal topography were evaluated on the SEM photographs by degree of crystal coverage, crystal length, and consistency of crystal morphology, and conclusions were as the follows. 1. Polyacrylic acid solution etched slightly the enamel surface, and the difference of etching effect by its concentration was not observed. 2. The effect of concentration of ployacrylic acid on the crystal formation was less, especially that of 20%-40% polyacrylic acid. was almost not different. 3. Concentration of the sulfate ion was a determinant factor in precipitating crystals on the enamel. The experimental crystal growth solutions containing 0.1M sulfate ion did not make crystal formation but those containing over 0.2M sulfate ion did. 4. The degree of crystal coverage showed a tendency to increase and then decrease according to the concentration of sulfate ion in the 20%-40% polyacrylic acid. The experimental solutions containing 0.5 M sulfate ion showed the peak of degree of crystal coverage. 5. The crystal length showed a tendency to decrease by increment of sulfate ion in the polyacrylic acid solution. 6. There was a tendency to increase the frequency of random arrangement of short crystals when increasing the concentration of sulfate ion in the polyacrylic acid solution. The lower concentration of sulfate ion in the plyacrylic acid solutions tended to make spherulitic arrangement of crystals, the higher concentration of sulfate ion, the more random arrangement of crystals, The experimental solutions containing 0.5M sulfate ion showed more spherulitic arrangement than random arrangement of crystals. 7. The best one of these experimental crystal growth solutions was 30%polyacrylic acid solution containing 0.5M sulfate ion.

Effect of phase interactions on crystal stress evolution over crystal orientation space under elastoplastic deformation of two-phase polycrystalline solids

Han, T.-S.,Chung, S.-Y.,Kim, Y.-W.,Kim, S.Y. Pergamon Press 2015 Journal of the mechanics and physics of solids Vol.76 No.-

It has been known for decades that crystal stress directions move toward the vertices of the single crystal yield surface (SCYS) during plastic flow of polycrystalline solids to satisfy the deformation compatibility among crystals. The alignment of crystal stress with a SCYS vertex is affected not only by plastic anisotropy, but also by other factors such as elastic anisotropy, loading direction, and grain interactions. Among the factors contributing to the degree of alignment, the effect of phase interactions on the crystal stress evolution during plastic flow has not been extensively investigated. In this research, the effect of phase interactions on the crystal stress direction evolution is investigated using simulations of an elastoplastically deforming two-phase (Cu/Fe) polycrystalline solid calibrated to a neutron diffraction experiment. By mapping the simulated crystal stresses over the crystal orientation space, crystal-orientation-dependent nonuniform partitioning of the crystal stress between phases can be observed. An analysis of the distribution of angles between the SCYS vertex and the crystal stress based on the simulation of the two-phase material shows that the crystal stress evolution pattern during plastic flow is strongly affected by phase interactions. These interactions result in low alignment and greater dispersion angles between the crystal stresses and SCYS vertices, particularly in the strong phase.

건축디자인에서의 크리스털(Crystal) 원리 적용에 관한 연구

정경태 대한건축학회지회연합회 2019 대한건축학회연합논문집 Vol.21 No.1

Nowadays, architects have sought variety of approaches to discovering a geometrical algorithm in nature and speculating new architectural forms. This study aims to establish the direction of the actual architectural design process based on the theoretical research of architectural design process using the properties of crystal. It is meaningful that the research may lead to in-depth and diverse form finding speculation in the morphological aspect. Furthermore, it is crucial to create unexpected architectural forms. In this study, the geometrical feature and material properties of crystal focusing Pyrite were analysed and applied from the initial stage of design to the final architectural implementation stage. The specific process to develop this is divided into four stages: investigation and analysis of crystal, prototype form, single crystalline space and implementation of crystal architecture. The new form finding is not an architect's creation, but an architectural form that is discovered within the algorithm, the design language inventory, and the materiality reflecting direct and indirect investigation and analysis of the crystal. It is anticipated that this study will prove invaluable reference, help architects and design professionals speculate unpredictable form finding, which is followed by the continued crystal analysis and application to architecture design. 오늘날 건축가들은 자연에서 기하학적 원리를 발견하여 새로운 건축적 형태를 찾아내기 위해 다양한 접근 방법을 모색해 왔다. 본 연구에서는 크리스털의 특성과 이를 적용한 건축디자인 사례들의 이론적 고찰을 바탕으로 실제 건축디자인 프로세스의 방향성을 정립하고자하였다. 이 연구를 통해 심도 있는 다양한 형태적 연구가 이뤄질 수 있고, 더 나아가 결과물로서 예상치 못한 흥미로운 건축적 형태를 창출해 낼 수 있다는데 그 의의가 있다. 이에 본 연구에서는 황철석(Pyrite)을 중심으로 크리스털의 기하학적 특징과 재료적 물성을 분석한 후, 디자인 초기 단계부터 최종 건축적 실현 단계까지 적용하였다. 이를 발전시켜 나가는 구체적인 프로세스를 크리스털에 대한 조사 분석, 프로토타입(prototype) 구축 , 크리스털라인 단일 공간, 크리스털 건축의 실현의 네 단계로 구분하여 제시하였다. 본 연구에서의 새로운 형태는 건축가가 창조해내는 것이 아닌 크리스털에 대한 직간접적인 조사 분석을 통해 구축된 알고리즘과 설정된 디자인 언어, 그리고 물성이 그대로 반영되어 그 건축적 형태가 발견되어지는 것이다. 건축가들, 그리고 디자인 관련 전문가들에게 예측 불가능한 새로운 형태를 찾기 위한 참고자료가 될 것이며, 향후 지속적인 크리스털에 대한 분석과 설계에의 적용에 관한 연구가 이뤄지기를 기대한다.

Evaluation of Micro-Void Defect of ε-HNIW Crystals in Drowning-Out Crystallization

Lee, Chang Woo,Kim, Sungkook,Kim, Woo-Sik The Society of Chemical Engineers, Japan 2011 Journal of chemical engineering of Japan Vol.44 No.6

<P>The evaluation of density and micro-void defects of <I>ε</I>-HNIW crystals was investigated in the drowning-out crystallization. Also, methods to quantitatively evaluate the crystal void defects were developed by using pycnometer and differential scanning calorimeter. Since the <I>ε</I>-HNIW crystals were re-constructively transformed from <I>β</I>-HNIW, which was crystallized out by drowning-out crystallization, the density and defect of <I>ε</I>-HNIW crystals were predominantly determined by the growth process during the phase transformation. Due to contradictory contributions of crystallization conditions on crystal defects, the crystal density was maximized at around the anti-solvent feeding time of 120 min and temperature of 25°C within ranges of the anti-solvent feeding time and temperature from 0–180 min and 5–30°C, respectively. Based on comparison of the measured crystal density with ideal one (2.044 g/cm<SUP>3</SUP>), the void defects of crystals were estimated. In addition, the thermal energies related with the solid-state phase transition from ε-HNIW to γ-HNIW and decomposition of HNIW were indicated to successful quantification of crystal defects owing to the significant changes of the thermal energies with the crystal density. Using the X-ray microscopic analysis with 80 nm resolution, it was proven that the micro-void defects in the crystal existed obviously to cause the change of crystal density and thermal properties.</P>

단결정 실리콘 잉곳 결정성장 속도에 따른 고-액 경계면 형성 및 Defect 최적화

전혜준(Hye Jun Jeon),박주홍(Ju Hong Park),블라디미르 아르테미예프(Vladimir Artemyev),정재학(Jae Hak Jung) 한국태양광발전학회 2020 Current Photovoltaic Research Vol.8 No.1

It is clear that monocrystalline Silicon (Si) ingots are the key raw material for semiconductors devices. In the present industries markets, most of monocrystalline Silicon (Si) ingots are made by Czochralski Process due to their advantages with low production cost and the big crystal diameters in comparison with other manufacturing process such as Float-Zone technique. However, the disadvantage of Czochralski Process is the presence of impurities such as oxygen or carbon from the quartz and graphite crucible which later will resulted in defects and then lowering the efficiency of Si wafer. The heat transfer plays an important role in the formation of Si ingots. However, the heat transfer generates convection in Si molten state which induces the defects in Si crystal. In this study, a crystal growth simulation software was used to optimize the Si crystal growth process. The furnace and system design were modified. The results showed the melt-crystal interface shape can affect the Si crystal growth rate and defect points. In this study, the defect points and desired interface shape were controlled by specific crystal growth rate condition.