• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.383-383
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• 2011

We fabricated thermal annealing-free polymer solar cells (PSC) by processing with additive and applied to flexible substrates. The 1, 8-Diiodooctane of 3 vol% blended with active solution resulted in enhancement of $J_{SC}$ due to increase of light absorption and hole mobility as improving the crystallinity of P3HT. In addition, the $V_{OC}$ of PSCs with additive was improved by inserting $TiO_2$ layer without any treatment. The $TiO_2$ layer prevented the direct contact between active layer and Al electrode and reduced the charge recombination near Active/Al interface. It was confirmed by calculation of J0 and photo-voltage transient measurement. The power conversion efficiencies of annealing-free PSCs using additive for ITO glass and flexible (ITO PEN) substrate were obtained 3.03% and 2.45%, respectively.

• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.777-783
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• 1994

Oxidation behavior of hot-pressed silicon nitride ceramics with various sintering additives has been investigated. The weight gain of each specimens has shown in the range of 0.11 mg/$\textrm{cm}^2$ ~3.4 mg/$\textrm{cm}^2$ at 140$0^{\circ}C$ for 192 h and eleven compositions have shown good oxidation resistance with the weight gain below 0.5 mg/$\textrm{cm}^2$. The oxidation rate has been shown to obey the parabolic rate law and the oxidized surface has consisted of $\alpha$-cristobalite and M2Si2O7 or MSiO3 (M=rare earth or transition metals) phase. The oxidation rate of each specimens has related to the eutectic temperature between additive oxide and SiO2, and ionic radius of additive oxides, respectively. From the above results, it could be concluded that the oxidation behavior of hot pressed silicon nitride is dominated by the high temperature properties of grain boundary glassy phase and the high temperature properties of grain boundary glassy phase are affected by the ionic radius of additive oxides.

• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.331-335
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• 1999

Mechanical propeties of $Y_2O_3$-containing tetragonal $ZrO_2$ polycrystals(Y-TZP) were investigated. Several additives were used to modify the hardness fracture toughness of Y-TZP. The effects of these individual additives were discussed and their interactions were also analyzed. Each additive, such as CoO, $Fe2O3, MnO_2$ was found to deteriorate the mechanical propeties of Y-TZP when it was used singly. But the fracture toughness of Y-TZP was singnificantly improved when these additives and $Al_2O_3$ were added in combination at a certain ratio.

• Journal of the Korean Ceramic Society
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• v.42 no.1
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• pp.16-21
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• 2005

The effect of additive composition, using AlN and $Er_{2}O_{3}$ as sintering additives, on the mechanical properties of liquid-phase-sintered, and subsequently annealed SiC ceramics was investigated. The microstructures developed were quantitatively analyzed by image analysis. The average thickness of SiC grains increased with increasing the $Er_{2}O_{3}/(AlN + Er_{2}O_{3})$ ratio in the additives whereas the aspect ratio decreased with increasing the ratio. The mechanical properties versus $Er_{2}O_{3}/(AlN + Er_{2}O_{3})$ ratio curve had a maximum; i.e., there was a small composition range at which optimum mechanical properties were realized. The best results were obtained when the ratio ranged from 0.4 to 0.6. The flexural strength and fracture toughness of the SiC ceramics were $550\~650\;MPa$ and $5.5\~6.5$ MPa${\cdot}m^{1/2}$, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.5
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• pp.378-383
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• 1998

Microstructure and additive effect of Lead Zirconate-Titanate(PZT) ceramics prepared by molten salt synthesis method with additives $Nb_2O_5, Fe_2O_3$ and MnO were investigated.The grain PZT ceramics ws decreased with the increase $Nb^{5+} or Fe^{3+}$ while increased with the increase $Mn^{2+}$ addition. The relative resistivity of PZT ceramics was increased with the increase $Mn^{5+}$ addition, while decreased with the increase $Mn^{2+}$ addition. And the dielectric and the piezoelectric constant of PZT ceramics showed 2,100 and 342pC/N at $Mn^{5+}$ addition of 0.75 mol%, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.959-962
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• 2001

In this study, the piezoelectric and dielectric properties and Temperature stability of resonant frequency with MnO$_2$doped 0.36Pb(Sc$_{1}$2/Nb$_{1}$2/)O$_3$- 0.25Pb(Ni$_{1}$3/Nb$_{2}$3/)O$_3$-0.39PbTiO$_3$(hereafter PSNNT) were investigated. The tetagonality of crystal structure was developed with increasing MnO$_2$additive content. With increasing MnO$_2$additive content, the electromechanical coupling factor and quality factor were increased. Electromechanical coupling k$_{p}$ and quality factor Q$_{m}$ at MnO$_2$doped with 2.0mol% were showed highest value of 55.6% and 252. In the case of specimen for MnO$_2$doped with 2mol%, temperature dependance of resonant frequency had a good properties.ies.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.9
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• pp.726-730
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• 2001

Temperature stabilities of dielectric constraints and resonant frequencies of the substrates are very important in piezoelectric ceramics oscillators and filters. In this study, it was investigated temperature stability of the length-extensional vibration mode of Pb(Zr$\_$y/Ti$\_$1-y/)O$_3$+x[wt%]Cr$_2$O$_3$ ceramics. The mode can be utilized in fabricating ultra-small 455 kHz IF devices. Addition of Cr$_2$O$_3$ in morphotrophic phase PZT decreased the variations of dielectric constant, electro-mechanical coupling factor k$\_$31/ and resonant frequency by thermal shock. As additive weight of Cr$_2$O$_3$increased, the temperature coefficient of resonant frequency changed from positive number to negative one. And the composition tith temperature coefficient of resonant frequency was shifted to the one with increased Cr$_2$O$_3$ additive weigh by thermal aging.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.110-113
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• 2016

(YNdSm)-Ba-Cu-O system high Tc composite superconductors were directionally grown by zone melting process, having large temperature gradient, in air atmosphere. Cylindrical green rods of $(YNdSm)_{1.8}Ba_{2.4}Cu_{3.4}O_x$ [(YNS)1.8]composite oxides by CIP (cold isostatic pressing) method using rubber mold were fabricated. The microstructure and superconducting properties were investigated by XRD, TEM and SQUID magnetometer. The size of nonsuperconducting $(YNdSm)_2BaCuO_5$ inclusions of the melt-textured (YNS)1.8 sample with $CeO_2$ additive were remarkably reduced and uniformly distributed within the superconducting (YNS)1.8 matrix. (YNS)1.8 samples, with / without $CeO_2$ additive, showed an onset $T_c{\geq}90K$ and sharp superconducting transition. The critical current density $J_c$ value of the (YNdSm)1.8 superconductor with $CeO_2$ additive were 840 A, $1.2{\times}104A/cm^2$ in 77 K, 0 Tesla by direct current transport method.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.368-372
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• 2011

Aluminum nitride (AlN) has excellent thermal conductivity, whereas it has some disadvantage such as low sinterability. In this study, the effects of sintering additive content and sintering condition on thermal conductivity of pressureless sintered AlN ceramics were examined on the variables of 1~3 wt% sintering additive ($Y_2O_3$) content at $1900^{\circ}C$ in $N_2$ atmosphere with holding time of 2~10 h. All AlN specimens showed higher thermal conductivity as the $Y_2O_3$ content and holding time increase. The formation of secondary phases (yttrium aluminates) by reaction of $Y_2O_3$ and $Al_2O_3$ from AlN surface promoted the thermal conductivity of AlN specimens, because the secondary phases could reduce the oxygen contents in AlN lattice. Also, thermal conductivity was increased by long sintering time because of the uniform distribution and the elimination of the secondary phases at the grain boundary by the evaporation effect during long holding time. A carbothermal reduction reaction was also affected on the thermal conductivity. The thermal conductivity of AlN specimens sintered at $1900^{\circ}C$ for 10 h showed 130~200W/mK according to the content of sintering additive.

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.05a
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• pp.41-41
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• 2002