• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.1
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• pp.74-81
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• 1991

The temperature profile of Czochralski single crystal growth system was simulated considering the fluid flow and surface radiation heat transfer. View factors of surface elements were calculated for radiation heat transfer. Two phases(solid and liquid) were treated as a continuous phase by assigning artificial large viscosity to the solid phase and latent heat was accounted by iterative heat revolution method. The solidification model was applied to solid front of the pure Ga during the melting to verify the model. The whole simulation model of CZ system was applied to the growth Al single crystal.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.4
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• pp.172-175
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• 2003

We have investigated effects of the lattice mismatch between the LPE films and the substrates. We have grown $La_{2-x}Sr_{x}CuO_{4}$(x=0.1 to 0.15) single crystalline films on single crystalline substrates having different lattice parameter ratio c/a e.g., $La_{2-x}Sr_{x}Cu_{1-y}Zn_{y}O_{4},\;La_{2-x}Ba_{x}CuO_{4},\; LaSrAlO_{4}\;and\;La_{2-x}Sr_{x}Cu_{1-y}Al_{y}O_{4}$ etc., using the IR-LPE technique. The superconducting properties of the grown films were found to vary significantly depending on the lattice mismatch with different substrates.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.5
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• pp.168-173
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• 2020

To analyze and describe the behavior and mechanisms occurring in the thermal oxidation process of AlN, bulk AlN single crystals were thermally treated with different temperatures. As a result, it was confirmed that full-scale oxidation of bulk AlN and growth of Al-oxide occurred from the temperature of 800℃, which confirmed that the weight% of O elements tended to increase while the N elements decreased with increasing the temperature. In the case of thermal treatment at 900℃, the grown Al-oxides were merged with neighboring Al-oxides and began to form α-Al₂O₃ poly-crystals. During thermal treatment at the temperature of 1000℃, hexagonal pyramidal shaped poly-crystalline α-Al₂O₃ was clearly observed. Through the X-ray diffraction pattern analysis, the changes of surface crystal structure according to the temperature of bulk AlN were investigated in detail.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.4
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• pp.170-174
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• 2018

AlN crystal is been developing in global site for many years and 1 inch diameter wafer was already developed but it is demanding the efforts for the better quality. On the other hand, also the 2-inch size is developing recently to reduce the unit cost for manufacturing and to use to fabrication of the UV LED chips. In this study, we tried to evaluate the possibility of bulk AlN crystals on his thin films by PVT method. The AlN thin film was grown on SiC single crystal 2" wafer by HVPE method. We successfully grew AlN bulk crystal of a thickness of 7 mm using its thin film of a thickness of $10{\mu}m$ as a seed crystal. The resultants of AlN crystals were identified by metallurgical microscope, optical stereographic microscope and DCXRD measurement.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.2
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• pp.84-88
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• 2016

AlN single crystals were grown by the PT (Physical vapor transport) method with position-changable induction coil. And the graphite crucible dimensioned ${\Phi}90{\times}H120$ was used on processing. The temperature was $1950{\sim}2050^{\circ}C$ and ambient pressure was 150~1 Torr. And the hot-zone was changed according to times on growing for result comparison. When hot-zone by coil is located below far enough (> 40 mm) from AlN crystal concentration position, the as-grown crystals physical size is better ($300{\mu}m/hr$) than another condition, but the condition-reproducibility was very poor. However the closer the distance between hot-zone and AlN growing posion, the smaller the size of as-grown crystal and the rarer the generation of the crystal nuclear, but the crystal growing condition is stable for quality. The best condition for both growth rate and quality is gained when the starting position of hot-zone coil is about 20 mm distance from growing position. For the best growth condition, the position of hot-zone is very sensitive factor and the further more the condition of speed of coil shift also must control.

• Bulletin of the Korean Chemical Society
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• v.18 no.3
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• pp.311-316
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• 1997

The synthesis and characterization of the mononuclear group 13 heterocyclic carboxaldehyde methyldithiocarbazate complexes Me2M[NC5H4CRNNC(S)SCH3] (M=Al, R=H(1); M=Ga, R=H(2); M=Al, R=CH3(3); M-Ga, R=CH3(4); M=In, R=CH3(5)) are described. Compounds 1-5 were prepared by the reaction of MMe3 (M=Al, Ga, In) with 2-formy or 2-acetylpyridine-S-methyldithiocarbazate in toluene. These compounds 1-5 have been characterized by microanalysis, NMR (1H, 13C) spectroscopy, mass spectra, and single-crystal X-ray diffraction. X-ray single-crystal diffraction analyses reveal that 4-5 are mononuclear metal compounds with coordination number of 5 and N,N,S coordination mode.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.2
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• pp.162-166
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• 1993

Spodumene$(LiAlLi_2O_6)$ single crystal was grown by Floating Zone process using the image furnace having the halogen lamp as heat sources. The crystal had the dimension of 50~60mm length and 6~8mm diameter. The colors of as-grown crystals were green, black and pale green respectively. The composition of the crystal was analized by XRD and FUR measurement. Growth orientation was examined by Laue back reflection pattern and for measuring the light transmittance, OPtical transmittance was measured.

• Journal of the Korean Ceramic Society
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• v.34 no.8
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• pp.834-842
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• 1997

Controlled Ca impurity implanted inner crack-like pore in the high purity alumina single crystal, sapphire, had been created by micro-fabrication technique, which includes ion implantation, photo-lithography, Ar ion milling, and hot press technique. The morphological change and the healing of cracklike pore in Ca doped high purity single crystal alumina, sapphire, during high temperature heat treatment in vacuum were observed using optical microscopy. The dot-like surface roughening was developed and hexagon like crystal appeared on inner surface of crack-like pore after heat treatment. Bar type crystals, probably CaO.6Al2O3, were observed on the inner surface after 1 hour heat treatment at 1, 50$0^{\circ}C$, but this bar type crystal disappeared after 1 hour heat treatment at 1, $600^{\circ}C$. This disappearance means that there should be a little increase of Ca solubility limit to alumina at this temperatures.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3303-3310
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• 2012

Two single crystals of fully dehydrated partially $Li^+$-exchanged zeolite X were prepared by the exchange of Na-X, $Na_{92}Si_{100}Al_{92}O_{384}$ (Si/Al = 1.09), with $Li^+$ using aqueous 0.1 M $LiNO_3$ at 293 (crystal 1) and 333 K(crystal 2), followed by vacuum dehydration at 623 K and $1{\times}10^{-6}$ Torr for 2 days. Their structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $Fd{\overline{3}}$ at 100(1) K. Their structures were refined using all intensities to the final error indices (using the 1281 and 883 reflections for which ($F_o$ > $4{\sigma}(F_o)$) $R_1/R_2$ = 0.075/0.244 and 0.074/0.223 for crystals 1 and 2, respectively. Their compositions are seen to be ${\mid}Li_{86}Na_6{\mid}[Si_{100}Al_{92}O_{384}]$-FAU and ${\mid}Li_{87}Na_5{\mid}[Si_{100}Al_{92}O_{384}]$-FAU, respectively. In crystal 1, 17 $Li^+$ ions per unit cell are at site I', 15 another site I', 30 at site II, and the remaining 16 at site III; 2 $Na^+$ ions are at site II and the remaining 4 at site III'. In crystal 2, 32 and 30 $Li^+$ ions per unit cell fill sites I' and II, respectively, and the remaining 25 at site III'; 2 and 3 $Na^+$ ions are found at sites II and III', respectively. The extent of $Li^+$ exchange increases slightly with increasing ion exchange temperature from 93% to 95%.

• Journal of the Korean Ceramic Society
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• v.31 no.3
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• pp.249-256
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• 1994

By surface structure and X-ray topographic observation, growth mechanism of NAB single crystal grown by TSSG technique using a BaB4O7 flux was studied. Surface structure of grown crystals were investigated by optical microscope. Growth history and crystal defects included within grown crystal were investigated using X-ray topography. The {001} faces were grown by 2-D nucleation growth. As decreasing cooling rate, growth mechanism of {111} and {11} was changed from 2-D nucleation growth to the growth by screw dislocation. Only surface striations developed parallel to a-axis were observed on {010} faces. Growth sector of NAB crystals were divided into {001}, {111}, {010}, {021}, {11}. The inclusion which was usually trapped between {001} faces was investigated.