• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.260-261
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• 2005

The heterolayered thick/thin structure consisting of $Pb(Zr_{0.52}Ti_{0.48})O_3$ and $BaTiO_3(BT)$ were fabricated by a sol-gel process. PZT powders, prepared by the sol-gel method, were mixed with an organic vehicle and the PZT thick films were fabricated by the screen printing techniques on alumina substrate with Pt electrodes. The microstructural and dielectric characteristics of the stacked heterolayered PZT/BT/PZT films were investigated by varying the number of coating $BaTiO_3$ layers. The existence of a $BaTiO_3$ layer between the PZT thick films of the tri-layer $Pb(Zr_xTi_{1-x})O_3/BaTiO_3/Pb(Zr_xTi_{1-x})O_3$thick/thin/thick film can greatly improve the leakage current properties of the PZT thick films. The average thickness of a PZT(5248)/$BaTiO_3$ heterolayered thick/thin film was 25$\mu$m. The relative dielectric constant and dielectric loss of the PZT(5248)/$BaTiO_3$-3 heterolayered thin film coated three times were 1087 and 1.00% at 1[MHz].

• Journal of the Korean institute of surface engineering
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• v.31 no.6
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• pp.334-344
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• 1998

Yew coating pmccss t.o form a surface layer ol CrN phasc on mild steel (A81 1020!, AlSI Hi3, 1Cr-0.5Mo steel (ASTM A213 and Nickrl-base superalloy (Inconel 718) was developed. Surlaces of various alloys t,n.ateii by chromizing for the formation ol Cr diffusion layer was subsequently trcaled by plasma nitriding in order t.o form the hard CrS coating layer on the surfaces. This duplex plasma surface tri-atments of chromizing and plasma nitriding have induced a lormation of a duplex-lrcated surfacr hyer of approximat~ls 70-80 $\mu\textrm{m}$thickncss with a iargcly improved microiiardnrss up to approxiniateW 1500Hv(50gf). The main cause for the lage improvment in the surface hardncss is altribilted to [.he fact that CrN and $Fe_xN$ phases are created successfully by ccliromizins and plasma nilriding treatment. High tenipera1,urc wear resislance of the duplex-treated mild steel and HI3 steels at $600^{\circ}C$ was examined. Comparing the duplex-treated specimens with the specimens treated only by chromizing, the rcsults shovmi that, thc wear volume of the duplex-treated mild skcl and 1113 stcel aSt.er a wear test, at $600^{\circ}C$ were reduced hy a Iactor of 8 and 3, respectively. Characteristics of the CrS phase by duplrx treatment were compared with $CrN_x$,/TEX> film by ion plating and the wear behaviors of CrN film lormed by two different nroccsses arc nea.riy identical.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.394-394
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• 2009

Water solubility of conjugated polymers may offer many applications. Potential applications of water-soluble conjugated polymers include the polymer light-emitting diode and new materials for nano and micro hollow-capsules, and bio- or chemo-sensors. We synthesized neutral polyfluorenes containing bromo-alkyl groups by the palladium catalyzed Suzuki coupling reaction. Bromo-alkyl side groups in neutral polyfluorenes were quaternized by tri-methyl amine solution. The electrochemical and optical properties of water-soluble conjugated polymers are discussed. This novel synthesized water-soluble conjugated polymers were used as a interfacial dipole layer between active layer and metal cathode in polymer solar cell for enhancement of open-circuit voltage (Voc), which is one of the most critical factors in determining device characteristics. We also investigated the device performance of polymer solar cell with different metal cathode such as Al, Ag, Au and Cu. In polymer solar cell, novel cationic water-soluble conjugated polymers were inserted between active layer and high-work function cathode (Al, Ag, Au and Cu).

• Journal of the Korean Ceramic Society
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• v.43 no.11 s.294
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• pp.715-723
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• 2006

Perovskite oxide materials are very important for the electronics industry, because they exhibit promising properties. With an interest in the obvious applications, significant effort has been invested in the growth of highly crystalline epitaxial perovskite oxide thin films in our laboratory. And the desired structure of films was formed to achieve excellent properties. $Y_1Ba_2Cu_3O_{7-x}$ (YBCO) superconducting thin films were simultaneously deposited on both sides of 3 inch wafer by inverted cylindrical sputtering. Values of microwave surface resistance R$_2$ (75 K, 145 GHz, 0 T) smaller than 100 m$\Omega$ were reached over the whole area of YBCO thin films by pre-seeded a self-template layer. For implementation of voltage tunable high-quality varactor, A tri-layer structured SrTiO$_3$ (STO) thin films with different tetragonal distortion degree was prepared in order to simultaneously achieve a large relative capacitance change and a small dielectric loss. Highly a-axis textured $Ba_{0.65}Sr_{0.35}TiO_3$ (BST65/35) thin films was grown on Pt/Ti/SiO$_2$/Si substrate for monolithic bolometers by introducing $Ba_{0.65}Sr_{0.35}RuO_3$ (BSR65/35) thin films as buffer layer. With the buffer layer, the leakage current density of BST65/35 thin films were greatly reduced, and the pyroelectric coefficient of $7.6\times10_{-7}$ C $cm^{-2}$ $K^{-1}$ was achieved at 6 V/$\mu$m bias and room temperature.

• Journal of the Korean Society for Heat Treatment
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• v.30 no.1
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• pp.13-16
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• 2017

$SnO_2$ single layer films and 2 nm thick Ni thin film intermediated $AZO/Ni/SnO_2$ trilayer films were deposited on glass substrate at room temperatures by RF and DC magnetron sputtering and then the optical and electrical properties of the films were investigated to enhance opto-electrical performance of $SnO_2$ single layer films. As deposited $SnO_2$ films show the optical transmittance of 81.8% in the visible wavelength region and a resistivity of $1.2{\times}10^{-2}{\Omega}cm$, while $AZO/Ni/SnO_2$ films show a lower resistivity of $5.8{\times}10^{-3}{\Omega}cm$ and an optical transmittance of 77.1% in this study. Since $AZO/Ni/SnO_2$ films show the higher figure of merit than that of the $SnO_2$ single layer films, it is supposed that the $AZO/Ni/SnO_2$ films can assure high opto-electrical performance for use as a transparent conducting oxide in various display applications.

• Korean Journal of Materials Research
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• v.3 no.4
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• pp.372-380
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• 1993

In order to improve the oxidative resistance of carbon/carbon composites, aluminium-isopropoxide and aluminium-tri-sec-butoxide sol were coated on the surface of 2D--carbon/carbon composiles and the effects uf coating were investigated. The effects of oxidative resistance were dominant in the case of catalyst/alkoxide mole ratio, 0.07, and $H_2O$/alkoxide mole ratio, 100. Through the dynamic TGA analysis with the heating rate of 20%/min, oxidative initiation tempera~ ture was enhanced about $80^{\circ}C$. The oxidative resistance effects of alkoxide sol were improved according to the times of coating. Also the 20% weight loss time of coated samples by TGA analysis was 20% better than that of un~ coated samples. The thickness of 1^{st} coated layer was about 3${\mu}$m and that of $2^{nd}$ and $3^{nd}$ coated layers was about respectively 4~5${\mu}$m and the weight loss were increased with the increasing of thermal shock test times.

• Journal of Information Display
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• v.12 no.4
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• pp.219-222
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• 2011

Iridium-(III)-bis[(4,6-di-fluorophenyl)-pyridinate-N,$C^2$' ]picolinate-based blue phosphorescent organic light-emitting diodes with different electron transport materials were fabricated. Each electron transport material had different electron mobilities and triplet energies. The device with 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene had the highest external quantum efficiency (20.1%) and luminous current efficiency (33.1 cd/A) due to its high electron mobility and triplet energy. The operational stability of each device was also compared with that of the others. The device with 2,2',2"(1,3,5-benzenetriyl)tris-(1-phenyl-1H-benzimidazole) was found to have a longer lifetime than the other devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.114-114
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• 2011

Graphene is the hottest topic in condensed-matter physics due to its unusual electronic structures such as Dirac cones and massless linear dispersions. Graphene can be epitaxially grown on various metal surfaces with chemical vapor deposition (CVD) processes. Such epitaxial graphene shows modified electronic structures caused by substrates. In the method for removal of the effect of substrate, there are bi, tri-layer graphene, gold intercalation, and oxygen intercalation. Here, We will present the changes of geometric and electronic structure of graphene grown on Ru(0001) by oxygen intercalation between graphene and Ru(0001). Using Scanning tunneling microscopy (STM) and spectroscopy (STS), we observed the aspect that the band gap features near the fermi level of graphene on Ru(0001) system is shifted and narrow. Based on the observed results, two effects by intercalated oxygen were considered.

• Journal of the Korean Ceramic Society
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• v.30 no.8
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• pp.678-684
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• 1993

Alumina composite membranes were prepared by chemical vapor deposition and evaporation-oxidation process. For CVD process, deposition was carried out using aluminum-tri-isopropoxide at 35$0^{\circ}C$, 2 torr by heterogeneous reaction, and for evaporation-oxidation process, alumina composite membranes were prepared by evaporation of aluminum and dry oxidation at 80$0^{\circ}C$. As deposition time increases, water flux and N2 gas permeability of the composite membranes prepared by both processes were reduced. Applying gas permeation model, permeability and cracking possibility of top layer were evaluated.

• Journal of Powder Materials
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• v.11 no.3
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• pp.224-232
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• 2004

Ni-diamond composite powders with nickel layer of round-top type on the surface of synthetic diamond (140/170 mesh) were prepared by the electroless plating method (EN) with semi-batch reactor. The effects of nickel concentration, feeding rates of reductant, temperature, reaction time and stirring speeds on the weight percentage and morphology of deposited Ni, mean particle size and specific surface area of the composite powders were investigated by Atomic Adsortion Spectrometer, SEM-EDX, PSA and BET. It was found that nucleated Ni-P islands, acted as catalytic sites for further deposition and grown into these relatively thick layers with nodule-type on the surface of diamond by a lateral growth mechanism. The weight percentage of Ni in the composite powder increased with reaction time, feeding rate of reductant and temperature, but decreased with stirring speed. The weight percentage of Ni in Ni-diamond composite powder was 55% at 150 min., 200 rpm and 7$0^{\circ}C$ .