• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.35-43
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• 1999

Microstructures and dielectric properties of (Sr$\_$1-x/Ca$\_$x/) TiO$_3$-0.006Nb$_2$O$\_$5/ (0.05$\leq$x$\leq$0.2) boundary layer ceramics were investigated. The samples fired in a reducing atmosphere(N$_2$) were painted on the surface with CuO paste for the subsequent grain boundary diffusion, and then annealed at 1100$^{\circ}C$ for 2 hrs. The metal oxide of CuO infiltrated by thermal diffusion from surface of sample presents continuously in not grain but only grain boundary, and makes up thin boundary phase. The SEM photo, and EDAX revealed that CuO was penetrated rapidly into the bulk along the grain boundaries during the annealing. The average grain sizes is continuously increased as the content of substitutional Ca is increased from 5[mol%] to 15[mol%], but the average grain size of the sample with content of 20[mol%] Ca is slightly decreased. In the samples with content of 10∼15[mol%] Ca, excellent dielectric properties were obtained as follows; dielectric constant <25000, dielectric loss <0.3[%], and capacitance change rate as a function of temperature <${\pm}$10[%], respectively. All samples in this study exhibited dielectric relaxation with frequency as a functior of the temperature.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1384-1386
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• 2001

In this paper, the structural and electrical properties of the $Sr_{1-x}Ca_xTiO_3$($0{\leq}x{\leq}0.2$)-based grain boundary layer ceramics were investigated by X-ray, SEM and V-I system. Increasing content of Ca, the average gram size and the lattice constant were decreased. The relative density of all specimens was > 96%. The 2nd phase formed by thermal diffusing from the surface lead to a very excellent electrical properties, that is, ${\varepsilon}_r$ > 50000, tan${\delta}$ < 0.05, $\Delta$C < ${\pm}$ 10%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.697-700
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• 2001

In this paper, the structural and electrical properties of the Sr$_{1-x}$ Ca$_{x}$TiO$_3$ (0$\leq$x$\leq$0.2) (0$\leq$r$\leq$0.2)-based grain boundary layer ceramics were investigated by X-ray, SEM and V-I system. Increasing the Ca content, the average grain size and the lattice constant were decreased. The relative density of all specimens was >96%. The 2nd phase formed by thermal diffusing from the surface lead to a very excellent electrical properties, that is, $\varepsilon$$_{r}$>50000, tan$\delta$<0.05, $\Delta$C< $\pm$ 10%.\pm$ 10%.%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.72-75
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• 2001

In this paper, the $Sr_{1-x}Ca_{x}TiO_{3}(0{\leq}x{\leq}0.2)$ 2)-based grain boundary layer ceramics were fabricated to measured dielectric properties and voltage-current properties. The sintering temperature and time were $1420\sim1520^{\circ}C$, 4hours, in $N_{2}$ gas, respectively. The structural and the dielectric properties were investigated by SEM, X-ray, HP4194A and K6517. The 2nd phase formed by thermal diffusion from the surface lead to a very high apparent dielectric constant, $\varepsilon_r$ > 50000. X-ray diffraction patterns exhibited cubic structure for all specimens. Increasing content of Ca, the peak intensity were decreased.ﱇﶖ⨀ਆᘍ܀㘱㔮㠹㬅K䍄乍

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.42-45
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• 2001

$(Ba_{0.6}Sr_{0.4}Ca_{x})TiO_{3}+yZrO_{2}$ wt% (x=0.10, 0.15, 0.20, y=0.5~3.0) specimens were fabricated by the mixed-oxide method and then the structural and dielectric properties as a function of the composition ratio and $ZrO_2$ contents were studied. All BSCT specimens showed dense and homogeneous structure without the presence of the seconds phase. The Curie temperature and the dielectric constant at room temperature decreased with increasing the Ca/Ba composition ratio and $ZrO_2$ content. The BSCT(50/40/10) specimens showed the excellent tunability property. And the tunability were increased with increasing the contents of $ZrO_2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.42-45
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• 2001

(Ba$_{0.6-x}$Sr$_{0.4}$Ca$_{x}$)TiO$_3$+yZrO$_2$wt% (x=1.10, 0.15, 0.20, y=0.5~3.0) specimens were fabricated by the mixed and ZrO$_2$ contents were studied. All BSCT specimens contents were studied. All BSCT specimens showed dense and homogeneous structure without the presence of the seconds phase. The Curie temperature and the dielectric constant at room temperature decreased with increasing the Ca/Ba composition ratio and ZrO$_2$ content. The BSCT(50/40/10) specimens showed the excellent tunability property. And the tunability were increased with increasing the contents of ZrO$_2$./TEX>.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.248-251
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• 1999

The microwave dielectric properties of The Dielectric Properties of $Ba_{1-x}$A$_{x}$(Mg$_{1}$3/Nb$_{2}$3/)O$_3$ (A = Sr, Ca, x = 0, 0.2 ,0.4 ,0.6, 0.8, 1.0) were investigated. In composition of $Ba_{1-x}$A$_{x}$(Mg$_{1}$3/Nb$_{2}$3/)O, densities are decreased with increasing x values. Grain sizes are decreased with Sr content and Increased with Ca content. The hexagonally ordered superstructure was observed in $Ba_{1-x}$Sr$_{x}$(Mg$_{1}$3/Nb$_{2}$3/)O$_3$(BSMN) systems, the intensity of superlattice increased with x value. In $Ba_{1-x}$Cr$_{x}$(Mg$_{1}$3/Nb$_{2}$3/)O$_3$(BSMN) systems, the additional diffraction patterns were shown. The highest value of $\varepsilon$$_{r}$ was shown in x=0.2 of BCMN systems and the value was 41.9. The highest Q$\times$f was shown in x=0.2 of BSMN systems and the value was 68,000. $\tau$$_{f}$ were shown 0 ppm/$^{\circ}C$ near x=0.8.TEX> near x=0.8.0.8.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.406-409
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• 2001

In this paper, the microstructure and the dielectric properties of the Sr$_{1-x}$ Ca$_{x}$TiO$_3$(0$\leq$$\chi$$\leq$0.2) -based grain boundary layer ceramics were investigated. The specimens were sintered from 142$0^{\circ}C$ to 152$0^{\circ}C$ for 4hr. in $N_2$ gas. The 2nd phase formed by thermal diffusing from the surface lead to a very high apparent dielectric constant, $\varepsilon$$_{r}$>50000. The structural properties of the specimens were studied by X-ray diffraction and SEM, EDX. All specimens exhibited cubic structure. Increasing content of Ca, the peak intensity were decreased.ed.d.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.4
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• pp.422-425
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• 1988

Pot experiment was conducted to determine the influence of liming on the uptake of $Sr^{90}$ by rice plant. The effect of lime application on the yield of rice plant has approved small slight increase of yield at the level of 150kg/10a only. Liming depressed the nutrient uptake of Mg, K, N and $P_2O_5$ except Ca by the rice plant. The $Sr^{90}$ content of rice plant diminished with increased lime application until to 300kg/10a. At the low pH and exchangeable Ca content of the soil, $Sr^{90}$ uptake of rice plant was high.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.24-29
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• 2002

In this paper, the microstructure and the dielectric properties of Sr$\_$1-x/CaxTiO$_3$(0$\leq$x$\leq$0.2)-based grain boundary layer ceramics were investigated. The sintering temperature and time were 1420∼152 0$\^{C}$ and 4 hours in N$_2$ gas, respectively. The average grain size and the lattice constant were decreased with increasing content of Ca, but the average grain size was increased with increase of sintering temperature. The second phase foamed by the thermal diffusion of CuO from the surface leads to verb high apparent dielectric constant, $\xi$$\_$r/>50000 and low dielectric loss, tan$\delta$<0.05. X-ray diffraction patterns of Sr$\_$1-x/CaxTiO$_3$ exhibited cubic structure, and the peaks shifted upward and the peak intensity were decreased with x. This is due to the lattice contraction as Sr is replaced by Ca with a smaller ionic radius. The specimens treated thermal diffusion for 2hrs in 1150$\^{C}$ exhibited nonlinear current-voltage characteristic, and its nonlinear coefficient(a) was overt 7.