• 소성∙가공
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• 제29권3호
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• pp.127-134
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• 2020

It is known that the difference of texture of the polycrystalline Al sheet is not a critical parameter for the formation of aligned nanopore arrays in anodic aluminum oxide (AAO). This will be related to the polycrystalline grain in the Al sheet. The texture of each grain in the polycrystalline Al sheet is different. The mixed textures of grains have the mixing effects on the nanopore structure of the AAO. Thus, the effect of Al texture on the nanopore structure of the AAO was investigated using three types of Al single crystals with (111), (200) and (220) textures in this paper. These three types of AAO layers were fabricated by the two-step anodizing method at 40 V and temperature of 0-5℃ in oxalic acid solution. In the nanopores formed on the AAO, the average area of one nanopore and the average roundness of one nanopore were measured were measured based on the SEM images. In the hexagon obtained by connecting nanopores on the AAO, the average standard deviation of one angle deviated from 120° was measured. In the AAO nanopores with texture of (111), (200) and (220) single crystal samples, the average area of one nanopore of (200) single crystal sample was the widest, followed by (111), (220) single crystals. The average circularity of one nanopore of (200) single crystal sample was the best, followed by (111), (220) single crystals. The average standard deviation of an angle from 120° of (220) single crystal sample was the largest, followed by (111) and (200) single crystals.

• 한국결정학회지
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• 제7권2호
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• pp.183-190
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• 1996

수열법을 이용하여 은(Ag)이 내장된 고온고압용 autoclave에서 KOH를 광화제로 하여 ZnO 단결정을 성장하고, LiOH 및 NH4OH의 첨가에 따른 결정외형의 변화에 대해 고찰하였다. 성장된 단결정은 연한 녹색을 띠고 있었으며 최대크기는 30×30×20mm3였다. KOH 광화제에 1.0-2.0M의 LiOH를 첨가하면 (0001)면의 flaw의 수가 감소하였다. 또한 NH4OH를 첨가한 결과 Vc/Va(c 축의 방향의 성장속도/a축 방향의 성장속도)가 증가함을 확인하였고, 이 방법을 응용하여 판상형의 종자결정 대신 침상형의 종자결정으로도 등방주상(Equant hexagonal prism)형의 ZnO 단결정을 성장할 수 있었다.

• 한국세라믹학회지
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• 제23권3호
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• pp.78-86
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• 1986

single crystals of various hexagonal ferrites were grown by a flux technique. For the growing experiment platinum crucibles of size 40 cc and a horizontal siliconit tube furnace were used. Charges consisted of the flux of BaO(SrO)/$B_2O_3$ and the composition of crystals in the system of BaO $(SrO)-Fe_2O_3-ZnO$. The BaO(SrO)/$B_2O_3$ molar ratio of the flux were varied from 1 to 3. Crystals up to 12.5mm in diameter were grown by slow cooling of melts from a maximum temperature of 1, 30$0^{\circ}C$or 1, 350$0^{\circ}C$ to 95$0^{\circ}C$ or 1, 00$0^{\circ}C$ The grown crystals exhibited a tabular hexagonal habits with very well developed ba-sal planes and narrow pyramidal faces of {1011} {1012} and {0001}. For the identification of the grown crystals X-ray diffraction studies were carried out. The effects of va-riations in flux ratio flux percentage and cooling rate on the quality of the grown crystals were studied. Cry-stal habits hillocks etch steps and growth spirals were observed by optical microscope. Magnetic properties of single crystals were measured.

• 한국세라믹학회지
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• 제22권5호
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• pp.43-46
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• 1985

Constitutional supercooling due to concentration gradient at solid-liquid interface in the melt can be avioded by increasing rotational speed for growing $LiNbO_3$ single crystals from the stoichiometric melt. Growth conditions for high quality crystals were determined by rotational speed by which other growth parameters were adjusted.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술대회지
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• pp.272-273
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• 2004

• 한국세라믹학회지
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• 제27권5호
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• pp.631-637
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• 1990

Lithium fluolide single crystals were grown by a floating zone method, with infrared radiation convergence type heater, which is free of contamination from the crucible wall. The crystals grown by this apparatus are 5cm in length and 5-6mm in diameter. The grown cryatal was examined by an optical microscope, XRD, Laue camera, Vickers hardness tester, and FTIR.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2005년도 High Temperature Superconductivity Vol.XV
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• pp.40-40
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• 2005

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술대회지
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• pp.275-276
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• 2004

• 한국세라믹학회지
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• 제25권6호
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• pp.699-703
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• 1988

Domain structures of LiNbO3 crystals grown by Czochralski method were examined according to the growth axis and the rotational speed of crystals. Ring shape and split domain structures were revealed in Z-axis and Y-axis grown crystals respectively. It was found that the domain structures of grown crystals were closely related to the solid-liquid interface shape during growth.

• 한국세라믹학회지
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• 제43권7호
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• pp.389-392
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• 2006

Electric field-induced phase transition from the tetragonal to rhombohedral phase was investigated for the <111> direction in tetragonal PZN-PT single crystals, which have spontaneous polarization along the <001> direction. From the strain and dielectric data, it was confirmed that the samples followed a tetragonal-orthorhombic-rhombohedral phase transition sequence with application of an electric field. This transition is different from the rhombohedral-tetragonal phase transition of <001> rhombohedral composition single crystals, in which a phase transition occurred without showing the intermediate orthorhombic phase.