• Journal of the Korean Vacuum Society
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• v.9 no.1
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• pp.16-23
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• 2000

The epitaxial growth of $CeO_2$ films has been investigated on three different substrates-Si(111), $SrTiO_3$(001), and MgO(001)-over wide range of growth parameters using oxygen-plasma-assisted molecular beam epitaxy. Pure-phase, single-crystalline epitaxial films of $CeO_2$ (001) have been grown only on $SrTiO_3$(001). We discuss the growth conditions in conjunction with the choice of substrates required to synthe-size this oxide, as well as the associated characterization by menas of x-ray diffraction, reflection high-energy electron diffraction, low-energy electron diffraction, and x-ray photoelectron spectroscopy and diffraction. Successful growth of single crystalline $CeO_2$ depends critically on the choice of substrate and is rather insensitive to the growth conditions studied in this investigation. $CeO_2$(001) films on $SrTiO_3$exhibit the sturcture of bulk $CeO_2$ without surface reconstructions. Ti outdiffusion is observed on the films grown temperatures above $650^{\circ}C$.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.161.2-161.2
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• 2007

• Journal of the Korean Magnetics Society
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• v.9 no.4
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• pp.184-189
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• 1999

1000 $\AA$ thick Fe films were epitaxially grown on MgO(001) by an rf sputtering and effects of substrate temperature on the structural and magnetic properties were investigated. X-ray diffraction intensity increased with increasing substrate temperature and inter-planar spacing $d_{(002)}$ decrease with increasing the temperature up to 25$0^{\circ}C$. The increased intensity and decreased inter-planar spacing were thought to be attributed to the enhancement of lattice match between Fe films and MgO, thus yielding good epitaxial growth. By using torque magnetometer, VSM and pole figure, very nice epitaxial growth of sputtered Fe films on MgO could be confirmed and $K_1$ value of Fe films grown at 25$0^{\circ}C$ was $4.6{\times}10^5\;erg/cc$, which was very similar to that of bulk single Fe crystal.

• Journal of the Korean Ceramic Society
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• v.47 no.4
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• pp.333-337
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• 2010

Domain structure and polarization switching in (001)-oriented $Pb(Mg_{1/3}Nb_{2/3})O_3-x%PbTiO_3$ (PMN-x%PT) crystals for x=20 and 35at% have been investigated in-situ by scanning force microscope (SFM) in a piezoresponse mode under a step DC electrical voltage. In the initial annealed condition, polar nano domains (PND) and domain striations oriented along {110} were observed in x=20 and x=35, respectively. For x=20, domain switching occurs by heterogeneous nucleation, where nucleation is not confined in the vicinity of domain boundaries, but rather can occur throughout the crystal volume. However, for x=35, domain switching tends to be preferentially initiated near pre-existing twin boundaries. With increasing the applying voltage, the nuclei density increased and assembled into {110} striations, indicating a stress-accommodated domain growth process. At higher voltage, nucleation occurs heterogeneously throughout the crystal volume.

• Journal of Environmental Health Sciences
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• v.19 no.3
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• pp.22-28
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• 1993

In order to investigate the hygienic chemical conditions of farm waters used as the potable and cleaning water for cow, we examined the pH, turbidity, KMnO$_4$ consumption, total hardness, chlorine, sulfate, NH$_3$-N, NO$_3$-N, lead, maganese, copper, zinc, fluoride and chrome for 78 farm waters around Kyunggi Province. Of 78 farm waters tested, average pH was 6.70+_0.06, turbidity 0.724 $\pm$ 0.081, KMnO$_4$ consumption 4.200 $\pm$ 0.256 mg/l, total hardness 107.46 $\pm$ 6.90 mg/l, NH$_3$-N 0.043 $\pm$ 0.037 mg/l, NO$_3$-N 8.096 $\pm$ 0.652 mg/l, chlorine 21.414 $\pm$ 2.187 mg/l, sulfate 12.737 $\pm$ 1.511 mg/l, lead 0.076 $\pm$ 0.001 mg/l, manganese 0.029 $\pm$ 0.004 mg/l, copper 0.018 $\pm$ 0.002 mg/l, zinc 0.055 $\pm$ 0.005 mg/l, chrome 0.048 $\pm$ 0.002 mg/l and fluorine 0.011 $\pm$ 0.001 mg/l. According to the geological characteristics, the concentrations of total hardness, NO$_3$-N, pH and chlorine in farm waters of Hwasung gun were higher than those in Yangpyung and Kwangju gun. In hygienic chemical items tested, there were high significanc among NO$_3$-N, total hardness, sulfate and chlorine. KMnO$_4$ consumption was significant with NH$_3$-N, sulfate and pH. But in heavy metals, there were significance between lead and copper, copper and chrome, and copper and fluorine.

• Korean Journal of Crystallography
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• v.8 no.2
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• pp.75-80
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• 1997

A perovskite relaxor ferroelectrics PMN is used as an important material to investigate the diffusive phase transition phenomena. In this study PMN single crystals were grown and the microstructure were observed. For the growth of PMN single crystals, the spontaneous nucleation technique and the TSSG technique were used. 2-5mm single crystals were grown from PbO self flux and it was observed that only PMN crystals were grown when excess MgO was added over 100% as flux. Single crystals with well developed (001) faces were obtained from PbO-B2O3 flux. single crystals larger than 1 cm were grown from PbO-B2O3 flux by TXXG technique. For higher quality crystals, optimization of the variables such as the rotation speed of seed crystal, the orientation of seed crystal, and cooling rate is needed. With grown crystals, it was confirmed by TEM diffraction pattern of thin plate crystal that the 1:1 ordering of Mg2+ and Nb5+ with small volume exists.

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.355-360
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• 1998

Epitaxial $Ba_{0.5}Sr_{0.5}TiO_3$thin films of two different thickness (~250 $\AA$ and ~1340 $\AA$) on MgO(001) prepared by a pulsed laser deposition method were studied by synchroton x-ray scattering measurements. The film initially grew on MgO(001) with a cube-on-cube relationship, maintaining it during further growth. As the film grew, the surface of the film became rough significantly, but the interface between the film and the substrate seemed to have changed little. In the early stage, the film was highly strained in a tetragonal structure with the longer axis parallel to the surface normal direction. As the growth proceeded further, it was mostly relaxed to a cubic structure with the lattice parameter of the bulk value and the mosaic distribution improved significantly in both in-plane and out-of-plane directions.

• Journal of the Korean Vacuum Society
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• v.16 no.1
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• pp.1-6
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• 2007

We have analyzed the atomic structure of O/Fe(100) and interface atomic structure of MgO deposited on Fe(100) surface using LEED I/V curve analysis. As the O adsorption on the Fe(100) surface, the first substrate interlayer distance is expanded by up to 16%. For 1ML MgO deposited on Fe(100) surface, the oxygen ions of MgO are located on-top of the Fe atoms, the interlayer distance at the MgO/Fe interface are expanded. From the AIA(average intensity mixing approximation) calculation, we find the interface structure of monolayer MgO on Fe(100) system has the two interface structure with MgO/FeO/Fe(100) and MgO/Fe(100). This supports the results of EELS experiment that shown existence of stretched FeO layer and coexistance of MgO/FeO/Fe(100) and MgO/Fe(100) structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.579-582
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• 2004

[ $Mg_xZn_{1-x}O$ ] thin films on (001) sapphire substrates have been deposited by pulsed laser deposition (PLD). The substrate temperature has been varied from $200^{\circ}C$ to $600^{\circ}C$ in order to control Mg content in $Mg_xZn_{1-x}O$ thin film. $Mg_xZn_{1-x}O$ thin films deposited at 200, 400 and $600^{\circ}C$ were annealed at temperatures of $800^{\circ}C$. The ratio of Mg was mesured by Rutherford backscattering spectrometry. The optical properties of $Mg_xZn_{1-x}O$ thin films were characterized by photomulinesence. The ratio of Mg was varied depending on the deposition temperatures which resulted in the change of energy bandgap.

• Progress in Superconductivity
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• v.9 no.1
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• pp.85-90
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• 2007

Lanthanum aluminate($LaAlO_3$) film has been prepared on single crystal and metal substrates by dip coating method. Lanthanum acetate and aluminum were prepared via ligand exchange starting from lanthanum nitrate hexahydrate and aluminum nitrate hexahydrate in acetate glacial acetic acid solution after being refluxed. Coating solution was obtained by diluting the gel with methanol and 2-methoxyethanol to adjust the total cation concentration to 0.67 M. Precursor coated film was prepared by dip-coating with a speed of 25 mm/min on various substrates such as $LaAlO_3$ (001), MgO(001), $SrTiO_3$(001) single crystal, LMO/MgO/Ni-alloy. Thin films have been obtained by heat treating the precursor film at various temperatures from $600^{\circ}C{\sim}900^{\circ}C$ and various heating rate from $0.83^{\circ}C/min{\sim}1.25^{\circ}C/min$ under $Ar/O_2$ mixture containing 1000ppm oxygen. The films have been characterized by scanning electronic microscopy (SEM) and X-ray diffraction (XRD). XRD analysis for the prepared film showed that $LaAlO_3$ thin films with a preferred orientation of (100) plane parallel to substrate surface were obtained at $800^{\circ}C(1.11\;^{\circ}C/min)$ on LMO/MgO/Ni-alloy substrate, but the intensity decreased with the increase of heat treatment temperature.