• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.194-194
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• 2008

Boron doped ZnO:Al(AZOB) thin films were prepared on glass substrates by dc magnetron sputtering. Influence of the annealing treatment on the electrical and optical properties of AZOB thin films were investigated. The lowest resistivity of $1.6\times10^{-3}\Omega$-cm was obtained at an annealing temperature of $400^{\circ}C$. The average transmittance of the films is over 80% in the visible range. It was also shown that by introducing boron impurity into AZO system improve the uniformity, the resistivity, and thermal stability of ZnO-based conducting thin films.

• Journal of the Korean Ceramic Society
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• v.34 no.4
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• pp.436-442
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• 1997

The bimodal distribution of CuCl nano-crystals precipitated in alumino-borosilicate glass matrix (30SiO2-45B2O3-7.5Al2O3-7.5Na2O-7.5CaO-2.5GeO2(mole %)) was investigated by TEM and the temperature dependent optical spectroscopy. Two types of CuCl particles with different size were observed by TEM and it was confirmed by the splitting of Z3 absorption peak at low temperature and the occurrence of deflection point in the optical spectra with temperature.

• Journal of Radiation Protection and Research
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• v.30 no.2
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• pp.77-84
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• 2005

The authors submit the data concerning the methods of obtaining semiconductor scintillators on the basis of the zinc chalcogenide crystal doped with impurities (Te, Cd, O, $Me^{III}-metals$ Al, In, etc.). Characteristics of such crystals and mechanisms for the semiconductor scintillator luminescence are described as well. The scintillator luminescence spectra maximums are located within the range 450-640nm, which depends on the method of preparing the scintillator. The luminescence decay time ranges within $0.5-10{\mu}s\;and\;30-150{\mu}s$. The afterglow level is less than 0.01% after $10-20{\mu}s$, and the radiation stability is ${\geq}5{\cdot}10^8$ rad. Thermostability of the output characteristics of new semiconductor scintillators on the basis of zinc selenide is prescribed by thermodynamic stability of the principal associative radiative recombination centers that come into existence due to the crystal lattice inherent imperfections. Certain application fields of the new scintillators are examined taking into account their particular qualities.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.861-867
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• 2017

In order to improve the capacity and cycling stability of Ni-rich NCA cathode materials for lithium ion batteries, the boron and cobalt were doped in commercial $Li_{1.06}Ni_{0.91}Co_{0.08}Al_{0.01}O_2$ (NCA) powders. Commercial NCA particles are mixed composites such as secondary particles of about $5{\mu}m$ and $12{\mu}m$, and the particle size was decreased by doping boron and cobalt. The initial discharge capacities of the boron and cobalt doped NCA-B and NCA-Co were found to be 214 mAh/g and 200 mAh/g, respectively, which are higher values than that of the raw NCA cathode material. In particular, NCA-Co exhibits the best discharge capacity of 157 mAh/g after 20 cycles, which is probably due to the enhanced diffusion of lithium ion by crystal growth along with the c-axis direction.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.232-236
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• 2020

In this study, the optical properties of CaF2-Al2O3-B2O3-TiO2 (CABT) system glass doped with rare earth ion, that is used in various light devices due to its excellent luminous properties, were analyzed as a function of kind of crystal phases formed and size of crystals generated in the glass matrix. TiO2 was added to control nucleation and crystallization, and Eu2O3 was added to enhance the luminescence characteristics. DTA analysis was performed to confirm the heat treatment condition of crystal generation, and XRD and SEM anal ysis were carried out for the crystal phase change of nanometer size. As a result of the analysis, the luminous properties of oxy-fluoride-based glass were improved duo to crystallization of nanometer size, but was rather degraded when excessively large crystals were generated.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.204-208
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• 1991

In this paper, the radiation properties of a far-Infrared using a PTC thermistor, the $BaTiO_3$+1.63mol% $Al_2O_3$+3.75mol% $SiO_2$+1.25mol% $TiO_2$(1/3 $Al_2O_3+xSiO_2$+(1-x) $TiO_2$; total x: 6.67mol%) ceramics, in order to progress the grade resistivity characteristics, by adding an ethanol solution of $Mn(NO_3){\cdot}6H_2O$ was investigated. The ceramics was fabricated by wet-mill method. The sintering temperature read 1300-1350$[^{\circ}C]$ and the holding time was 3 hours. The quantity of $Sb_2O_3$ and $Al_2O_3$ for an activation of the far-infrared radiation in ceramics was doped. In sintering, R-T property was measured by varying the grade temperature. The anatase-lighting apparatus and microstructures by using XRD and SEM were observed. $Sb_2O_3$. oxides additive. affected the semiconducting and emissivity and MnO was devoted an increase of resistivity. The specimen which only $Sb_2O_3$ is added to was high appeared far-infrared emissivity and Mno was not affacted the far-infrared radiation. The ceramics shows that it is effective in the structure of the human bodies as organic bodies and can be applied as electron device.

• Korean Journal of Materials Research
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• v.22 no.1
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• pp.42-45
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• 2012

The mechanical behavior and microstructural evolution during high temperature tensile deformation of recrystallized Ni3Al polycrystals doped with boron were investigated as functions of initial grain size, tensile strain rate and temperature. In order to obtain more precise information on the deformation mechanism, tensile specimens were rapidly quenched immediately after deformation at a cooling rate of more than $2000Ks^{-1}$, and were then observed by transmission electron microscopy (TEM). Mechanical tests in the range of 923 K to 1012 K were carried out in a vacuum of less than $3{\times}10^{-4}$ Pa using an Instron-type machine with various but constant cross head speeds corresponding to the initial strain rates from $1.0{\times}10^{-4}$ to $3.1{\times}10^{-5}s^{-1}$. After heating to deformation temperature, the specimen was kept for more than 1.8 ks before testing. The following results were obtained: (1) Flow behavior was affected by initial strain size; with decreasing initial grain size, the level of a stress peak in the true stress-true strain curve decreased, the steady state region was enlarged and elongation increased. (2) On the basis of TEM observation of rapidly quenched specimens, it was confirmed that dynamic recrystallization certainly occurred on deformation of fine-grained ($3.3{\mu}m$) and intermediate-grained ($5.0{\mu}m$) specimens at an initial strain rate of $3.1{\times}10^{-5}s^{-1}$ and at 973 K. (3) There were some dislocation-free grains among the new recrystallized grains. The obtained results suggest that both dynamic recrystallization and grain boundary sliding are operative during high temperature deformation.

• Current Optics and Photonics
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• v.2 no.1
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• pp.79-84
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• 2018

We present a novel and simple method to enable spatially selective $ZnAl_2O_4$ nanocrystal formation on the surface of $B_2O_3$-$Al_2O_3$-ZnO-CaO-$K_2O$ glass by employing localized laser heating. Optimized precipitation of glass-ceramics containing nanocrystals doped with $Eu^{3+}$ and $Yb^{3+}$ ions was performed by controlling $CO_2$ laser power and scan speed. Micro-x-ray diffraction and transmission electron microscopy revealed the mean size and morphology of nanocrystals, and energy dispersive x-ray spectroscopy showed the lateral distribution of elements in the imaged area. Laser power and scan speed controled annealing temperature for crystalization in the range of 1.4-1.8 W and 0.01-0.3 mm/s, and changed the size of nanocrystals and distribution of dopant ions. We also report more than 20 times enhanced downshift visible emission under ultraviolet excitation, and 3 times increased upconversion emission from $Eu^{3+}$ ions assisted by efficient sensitizer $Yb^{3+}$ ions in nanocrystals under 980 nm excitation. The confocal microscope revealed the depth profile of $Eu^{3+}$ ions by showing their emission intensity variation.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.657-662
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• 2014

We demonstrate a simulation of a parallel hybrid fiber amplifier in the C+L-band with a gain controlling technique. A variable optical coupler is used to control the input signal power for both EDFA and RFA branches. The gain spectra of the C+L-band are flattened by optimizing the coupling ratio of the input signal power. In order to enhance the pump conversion efficiency, the EDFA branch was pumped by the residual Raman pump power. A gain bandwidth of 60 nm from 1530 nm to 1590 nm is obtained with large input signal power less than -5 dBm. The gain variation is about 1.06 dB at a small input signal power of -30 dBm, and it is reduced to 0.77 dB at the large input signal power of -5 dBm. The experimental results show close agreement with the simulation results.

• Korean Journal of Materials Research
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• v.21 no.8
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• pp.450-455
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• 2011

[ $Al_2TiO_5$ ]has a high refractive index and good solubility of the chromophore in the $Al_2TiO_5$ lattice, which allows this structure to be a good candidate for the development of new ceramic pigments. However, pure $Al_2TiO_5$ is well known to decompose on firing at $900{\sim}1100^{\circ}C$. However, this process can be inhibited by the incorporation of certain metal cations into its crystalline lattice. In this study, the synthesis of gray ceramic pigment was performed by doping cobalt on the $Al_2TiO_5$ crystal structure. The $Al_2TiO_5$ was synthesized using $Al_2O_3$ and $TiO_2$, and doped with $Co_3O_4$ as a chromophore material. In order to prevent the thermal decomposition during the cooling procedure, MgO was added to samples by 0.05 mole, 0.1 mole, and 0.15 mole as a stabilizer. The samples were fired at $1500^{\circ}C$ for 2 hours and cooled naturally. The crystal structure, solubility limit, and color of the synthesized pigment were analyzed using XRD, Raman spectroscopy, UV, and UV-vis. $Al_2O_3$ was available for the formation of $CoAl_2O_4$, which should also be considered in order to explain the small amount of this phase detected in the sample with the higher $Co^{2+}$ content (${\geq}$ 0.03 mole). It was found that the solubility limit of $Co^{2+}$ in the $Al_2TiO_5$ crystal was 0.02 mole% through an analysis of Raman spectroscopy. Through the addition of a pigment with 0.02 mole% of $Co^{2+}$ to lime-barium glaze, stabilized gray color pigments with 66.54, -2.35, and 4.68 as CIE-$L^*a^*b^*$ were synthesized.