• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.105-110
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• 1994

L-arginine phosphate monohydrate (LAP) and tris(hydroxymethyl)aminomethane sulfate (THAMS) are new organic nonlinear optical materials for the device application such as the frequency conversion of laser radiation. In this work the single crystals of LAP and THAMS have been grown by the falling temperature method and the temperature difference method. The conditions of the growth parameters were presented and the grown crystals were characterized by means of optical microscopy, XRD and FTIR.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.3
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• pp.85-88
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• 2001

High oxygen pressure has been applied for a floating zone (FZ) crystal grower in order to grow high quality $TiO_2$(rutile) single crystals suitable for optical application. The $TiO_2$ crystals, grown under 0.3, 0.4, 0.5, and 0.8MPa oxygen pressure respectively, are all transparent and dark blue. The degree of the presence of sub-grain boundary in the crystal differs from the applied oxygen pressure. In particular, $TiO_2$ single crystals grown under0.5 MPa showed sub-grain boundary-free and estimated good for optical devices.

• Journal of the Korean Chemical Society
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• v.63 no.1
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• pp.29-36
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• 2019

A potentially tetradentate Schiff base ligand, 2-((2-((pyridin-2-ylmethylene)amino)ethyl)amino)ethan-1-ol (PMAE), and its cadmium(II) complex, [$Cd(PMAE)I_2$] (1), were prepared and characterized by elemental analysis, FT-IR, Raman, $^1H$ and $^{13}C$ NMR spectroscopies and single-crystal X-ray diffraction. In the crystal structure of 1, the cadmium atom has a slightly distorted square-pyramidal geometry and a $CdN_3I_2$ environment in which the PMAE acts as an $N_3$-donor. In the crystal packing of the complex, the alcohol and amine groups of the coordinated ligands participate in hydrogen bonding with iodide ions and form $R^2{_2}(14)$ and $R^2{_2}(8)$ hydrogen bond motifs, respectively. In addition to the hydrogen bonds, the crystal network is stabilized by ${\pi}-{\pi}$ stacking interactions between pyridine rings. The thermodynamic stability of the isolated ligand and its cadmium complex along with their charge distribution patterns were studied by DFT and NBO analysis.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.21-32
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• 1994

$CaF_2$ crystals were grown with various growth rates by Bridgman method, and the electrical properties of these were studied to examine the changes of ionic conductivities with growth rates by AC Impedance Analyzer. As the growth rates were higher, $CaF_2$ crystals were grown to polycrystals from single crystal. And as grain boundaries and various defects were altered, the ionic conductivities were changed dramatically. $YF_3$ added to $CaF_2$ for disorderizing $CaF_2$ structure and improving the number of $F^-$ carriers and vacancies in $CaF_2$ crystals. Then $Ca_{1-x}Y_XF_{2+X}$ crystals were gained. And the ionic conductivities of $Ca_{1-x}Y_XF_{2+X}$ crystals were investigated with $YF_3$ addition. The ionic conductivities of $CaF_2$ and $Ca_{1-x}Y_XF_{2+X}$ crystals with temperatures were compared. In addition, the effects of clusterings and defects on the electrical properties of solid electrolytes were researched.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.4
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• pp.17-22
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• 2009

Two different organic-inorganic hybrid thin film transistors (OITFTs) with the structures of glass/ITO/ZnO/PMMA/Al (staggered structure) and glass/ITO/PMMA/ZnO/Al (inverted staggered structure), were fabricated and their electrical and structural properties were compared. The ZnO thin films used as active channel layers were deposited by the atomic layer deposition (ALD) method at a temperature of $100^{\circ}C$. To investigate the effect of the substrates on their properties, the ZnO films were deposited on bare glass, PMMA/glass and ITO/glass substrates and their crystal properties and surface morphologies were analyzed. The structural properties of the ZnO films varied with the substrate conditions. The ZnO film deposited on the ITO/glass substrate showed better crystallinity and morphologies, such as a higher preferred c-axis orientation, lower FWHM value and larger particle size compared with the one deposited on the PMMA/glass substrate. The field effect mobility ($\mu$), threshold voltage ($V_T$) and $I_{on/off}$ switching ratio for the OITFT with the staggered structure were about $0.61\;cm^2/V{\cdot}s$, 5.5 V and $10^2$, whereas those of the OITFT with the inverted staggered structure were found to be $0.31\;cm^2/V{\cdot}s$, 6.8 V and 10, respectively. The improved electrical properties for the staggered OITFTs may originate from the improved crystal properties and larger particle size of the ZnO active layer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.714-719
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• 2017

The controlled synthesis of inorganic materials with a specific size and morphology is an important factor in the development of new materials in many fields, such as nanoparticles, medicine, electronics, semiconductors, pharmaceutical sand cosmetics. Solution crystallization is one of the most widely used separation processes in the chemical and pharmaceutical industries. Calcium carbonate has attracted a great deal of attention in industry because of its numerous applications. The mean crystal size, crystal size distribution and morphology are important factors in the continuous crystallization process. In this study, the continuous crystallization of calcium carbonate by the calcium chloride process was investigated. The mean crystal size and crystal size distribution data were obtained by a particle size analyzer. The morphological imaging of the crystalswasper formed by SEM. Under steady state operation, the mean crystal size change was small, but increasing the input concentration and mixing rate increased the crystal size. In this operation, some aragonite was found, but the main crystal phase was calcite.

• Korean Journal of Materials Research
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• v.2 no.4
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• pp.279-284
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• 1992

Oxygen adsorption on the single crystal NbC(111) surface was studied by high-resolution electron energy loss and ultraviolet photoelectron spectroscopy. On the NbC(111) surface, oxygen molecules as well as oxygen atoms were adsorbed. Oxygen atoms were located at the 3-fold hollow site of the NbC(111) surface with the frequency of 548c$m^{-1}$. It was found that oxygen molecules had vibrational frequency of 968c$m^{-1}$which was much lower than that of the free oxygen molecule. Also the work function of the NbC(111) surface has increased by adsorption of oxygen molecule. These suggest electron tranfer from the NbC(111) substrate to the 2p${pi}_g$ substrate of the oxygen molecule.

• Korean Journal of Materials Research
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• v.1 no.4
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• pp.184-190
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• 1991

Oxygen chemisorption on single crystal ZrC(111) surface was studied by high-resolution electron energy loss and ultraviolet photoelectron spectroscopy. At a low amount of oxygen exposure, adsorbed oxygen atoms construct $(\sqrt{3}{\times}\sqrt{3})R30^{\circ}$ structure. On the other hand, oxygen adsorption changes into $1{\times}1$ structure as the amount of oxygen exposure increases. The adsorbed oxygen atoms show smaller vertical distance from the Zr topmost layer in the $1{\times}1$ structure than in the $(\sqrt{3}{\times}\sqrt{3})R30^{\circ}$ structure and approach to the bridge site rather than 3-fold hollow site. The two different oxygen adsorption behavior comes from the two different surface stales of the clean ZrC(111) surface.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.143-150
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• 1997

The electrical properties of polysilicon thin films implanted with $B_2H_6$ diluted in $H_2$ as dopant source using ion mass doping technique and the effect of radiation damage on the dopant activation behavior were investigated. Comparing the SIMS profiles of boron in polysilicon films with that obtained from computer simulation using TRIM92 the most probable ion species were $B_2H_x\;^+$(x＝1, 2, 3‥‥) type molecular ions. As a result of the Implantation of energetic massive ions, a continuous amorphized layer was created in polysilicon films where the fraction of amorphized layer varied with doping time. This amorphization comes from the fact that mass separation of implanting species is not employed in this ion mass doping technique. In the dopant activation behavior, reverse annealing phenomenon appeared in the intermediate annealing temperature range for a severely damaged specimen. The experimental result showed that the off-state current of the p-channel polysilicon thin film transistor is dependent on the degree of radiation damage.

• Korean Journal of Crystallography
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• v.3 no.1
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• pp.23-30
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• 1992

a-SiC crystals were grown on the (001) plane of a-SiC seed crystals by sublimation method to find effects of pressure-reduction rate of the crystal growth furnace own the growth rate and orientstion of grown SiC crystals. Pressure-reduction rate at the initial growth stage affected the crystallinity of grown SiC crystals. In case of high pressure-reduction rate, growth rate was high and 3csic polycrystalline was grown on the seed. On the other hand, low pressure-reduction rate caused the growth rate to be slow and 6H-SiC single crystal was grown on the seed. However, even after growing SiC for 2 hours under the condition in which.