• Journal of the Korean Ceramic Society
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• v.25 no.5
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• pp.561-569
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• 1988

Mixtures of very small amounts of additive, carbon and silica(about 0.46${\mu}{\textrm}{m}$) which synthesized by the hydrolysis of ethyl silicate, the molar ratio of SiO2/C was fixed to 1/10, was nitrided at 145$0^{\circ}C$. It was considered that the optimum amount of additive to promote the nitridation reaction was below 2.0wt%. By the addition of additive, the nitridation reaction was promoted and formation of $\beta$-Si3N4 was promoted at 145$0^{\circ}C$ for 1hour, but, the nitridation reaction was decreased and the ratio of $\alpha$/$\beta$ of Si3N4, was increased at 145$0^{\circ}C$ for 5 hours. The crystal phase was $\alpha$ phase and the nitridation reaction was promoted and the particle size of silicon nitride was become smaller by the addition of $\alpha$-Si3N4, but silicon nitride of whisker-like form was produced by the addition of transition elements. There was a difference in the lattice constants of $\alpha$-Si3N4, but no difference in its of $\beta$-Si3N4 according to kinds of added substance and reaction time.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.405-409
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• 2003

The effect of substitution of Gd ions for Ca ions in the B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$(C $a_{1-x}$ G $d_{x}$)$_{2.03}$ C $u_{3.06}$ $O_{ 10+{\delta}}$/ (x=0.0~0.06) was investigated by measuring x-ray diffraction patterns, lattice constants, do resistivity and Hall effect. We found the solubility limit of Gd in the 110 K phase to be x < 0.015. Within the solubility limit, the c-axis seemed to decrease with increasing x. In the region of the 110 K single phase, the critical temperature $T_{c}$ gradually decreased with an increasing the Gd concentration x, corresponding to a small change of the carrier concentration.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.61-64
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• 2008

$Pr_{0.3}Sr_{0.7}Co_{0.3}Fe_{0.7}O_{3-\delta}$ (PSCF3737) was prepared and characterized as a cathode material for intermediate temperature-operating solid oxide fuel cell (IT-SOFC). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and electrical property measurement were carried out to study cathode performance of the material. XPS and EXAFS results proved that oxygen vacancy concentration was decreased and lattice constants of the perovskite structure material were increased by doping Fe up to 70 mol% at B-site of the crystal structure, which also extended the distance between oxygen and neighbor atoms. Thermal expansion coefficient (TEC) of PSCF3737 is smaller than that of $Pr_{0.3}Sr_{0.7}CoO_{3-\delta}$(PSC37) due to lower oxygen vacancy concentration. PSCF3737 showed better cathode performance than PSC37. It might be due good adhesion by a smaller difference of TEC between $Gd_{0.1}Ce_{0.9}O_2$ (CGO91) and electrode. Composite material PSCF3737-CGO91 showed better compatibility of TEC than PSCF3737. However, PSCF3737-CGO91 did not represent higher electrochemical property than PSCF3737 due to decreased reaction sites by CGO91.

• Korean Journal of Materials Research
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• v.13 no.1
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• pp.48-52
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• 2003

The substituted yttrium iron garnet systems $Y_{ 3-x}$/Gd$_{x}$X$0.2_{0.2}$ $Fe_{4.8}$ $O _{12}$ (x = 0.2, 0.4, 0.6) have been investigated by means of X-ray diffraction, Mossbauer spectroscopy and SQUID. The X-ray diffraction patterns at room temperature confirm the samples to have a single phase of the garnet structure over the whole composition range. The lattice constants of all the samples linearly change with increasing x due to the size of substituted ions in the dodecahedral sites. $Y_{3-x}$ $Gd_{x}$ X$Fe_{4.8}$ $In_{0.2}$ $O_{12}$ system which $Y_{3-x}$ ions are substituted with Gd$^{ 3＋}$ ions, the Mossbauer spectrum consists of three Zeeman sextets at room temperature, one due to the $Fe^{3＋}$ ions on the octahedral(a-) sites and the others due to the $Fe^{3＋}$ ions on the tetrahedral(d-, d'-) sites, respectively. From the hysteresis loop measured by means of SQUID over the whole composition range, the saturation magnetization $M_{s}$ and magnetic moments $\mu_{ B}$ per unit cell have been obtained. The increment of Gd-ion content causes $M_{s}$ and $\mu_{B}$ decrease while the increment of In-ion content does not.

• Journal of the Korean Ceramic Society
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• v.33 no.4
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• pp.405-410
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• 1996

The partial substitution of LiTaO3 with Al2O3 caused the variation of dielectric properties and a lower melting temperature yielding an easier growth of single crystal. The lattice constants and Raman band broadening were measured for the LiTaO3 solid solution in which the cations of Li+ and Ta5+ were partially substituted by Al3+ cation. The LiTaO3 type limit phases were obtained. ; Li1.15Al0.45Ta0.7O3 for cationic excess Li1.15Al0.45Ta0.7O3 for stoichiometry Li0.85Al0.05TaO3 for cationic deficit. The second phase was formed beyond the solubility limit. The limit phase (Li0.85Al0.05TaO3) in the region of cationic deficit showed the lowest Cuire temperature of 61$0^{\circ}C$ and melting point of 152$0^{\circ}C$ compared to the solid solutions in other regions (TMp=1$650^{\circ}C$, Tc=69$0^{\circ}C$ for LiTaO3)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.12
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• pp.949-955
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• 2010

Nd and Ti co-doped bismuth ferrite $(Bi_{1-x}Nd_x)(Fe_{1-y}Ti_y)O_3$ (x, y = 0, 0.05, 0.1, 0.2) ceramics and thin films were synthesized through the conventional mixed-oxide process and pulsed laser deposition (PLD), respectively. Nd and Ti co-doping effect was examined with emphasis on how these impurities affect phase formation behavior as there could be the improvement in leakage current problems often associated with multiferroic $BiFeO_3$ (BFO) thin films. The lattice constants of BFO ceramics decreased with Nd doping concentration up to 10mol%, while they further decreased with Nd and Ti co-doping to about 20%. BFO thin films obtained by the PLD process revealed random polycrystalline structure. Similar to bulk BFO ceramic, Nd and Ti co-doping effectively suppressed the formation of unwanted secondary phase and thus stabilized the perovskite phase in BFO thin films.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1239-1243
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• 1997

A phase analysis in the solid solution of (1-x) PbFe1/2Nb1/2O3-xPbCo1/2W1/2O3 is conducted by dielectric properties, heat capacity and E-P hysteresis at x=0.1 interval. Lattice constants and superlattice intensity are analyzed by the x-ray diffraction, and the temperature - composition phase diagram is determined. The system is found to form a solid solution of perovskite structure throughout the entire composition range, but the nature of phase transitions changes from ferroelectric-paraelectric for $0{\leq}x{\leq}0.5$ to antiferroelectric-paraelectric for $0.6{\leq}x{\leq}1.0$. The transitions of ferroelectric-paraelectric and antiferroelectric-paraelectric for $0.2{\leq}x{\leq}0.5$ and for $0.6{\leq}x{\leq}0.8$, respectively, are diffuse, while those of the ferroelectric-paraelectric and the antiferroelectric-paraelectric for $0.0{\leq}x{\leq}0.1$ and $0.9{\leq}x{\leq}1.0$, respectively are sharp.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.567-567
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• 2013

Surface plasmon resonance is the enhancement of electromagnetic wave caused by oscillation on the metal and dielectric interfaces. Surface plasmons with nanohole arrays provides an enhancedresonance for the specific wavelengths of interests. Asymmetric array of nanoscale structures can enable orientation dependent shift of resonance wavelengths when combined with the control of polarization for incident visible light, thus providing color tunability. Appropriate lattice constants along the direction of polarization in rectangular nanohole arrays can determine the resonance condition generating red (R), green (G), and blue (B) colors and potentially be applied to display applications. In ourprevious report, we have optimized the ion beam nanomachining conditions to fabricate the nanostructures on the metal film. We apply the fabrication conditions to make nanoscale hole arrays using 100 nm thick gold layer on the glass substrate with the optimal design of periodicities along x, y, and diagonal directions of a=440 nm, b=520 nm, c=682 nm, and the hole diameter of d=200 nm. Using the reflective light in dark field mode of optical microscope, we can observe different colors. When the polarizer is paralleled along a, b, or c direction, the represented color is changed to R, G, and B, respectively. We further map the color using i1 to correlate the conditions of the nanohole arrays with their characteristic color.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.171-172
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• 2008

$(Ba_{0.57}Sr_{0.33}Ca_{0.10})TiO_3$ (BSCT) thick films doped with 0.1 mol% $MnCO_3$ and $Yb_2O_3$ ($0.1{\sim}0.7$ mol%) were fabricated by the screen printing method on the alumina substrate. And the structural and electrical properties as a function of $Yb_2O_3$ amount were investigated. The lattice constants of the BSCT thick film doped with 0.1 mol% is 0.3955 nm. The specimen doped with 0.7 mol% $Yb_2O_3$ showed dense and uniform grains with diameters of about 6.3 mm. The thickness of all BSCT thick films was approximately 60 mm. The Curie temperature of the BSCT specimen doped with 0.1 mol% $Yb_2O_3$ was $18^{\circ}C$, and the dielectric constantand dielectric loss at this temperature was 4637 and 4.2%, respectively. The BSCT specimen doped with 0.1 mol% $Yb_2O_3$ showed the maximum value of $349{\times}10^{-9}C/cm^2K$ at Curie temperature. The figure of merit $F_D$ for specific detectivity of the specimens doped with 0.1 mol% $Yb_2O_3$ showed the highest value of $10.9{\times}10^{-9}Ccm/J$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.3
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• pp.96-101
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• 2001

In this study, diluted magnetic $Zn_{1-x}Mn_{x}Te$ epilayers were grown on GaAs(100) substrates by hot-wall epitaxy, and their characteristics were systematically examined. The maximum Mn composition of the $Zn_{1-x}Mn_{x}Te$ epilayers was 0.97. The crystallographic orientation was toward <100> and the structure of the $Zn_{1-x}Mn_{x}Te$ epilayers was the zincblende structure, identical to those of the GaAs substrate. With increasing the substrate temperature (350~$400^{\circ}C$), Mn composition increased (0.02~0.23) and he quality of the epilayer became worse. The lattice constants increased linearly with increasing Mn composition, but the band gap energy increased nonlinearly with increasing x.