• Electrical & Electronic Materials
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• v.10 no.7
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• pp.674-681
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• 1997

Ternary compound ceramics, (1-y-x) BaTiO$_3$-y SrTiO$_3$-x MgTiO$_3$(0.00 x 0.20), were fabricated by the conventional ceramic process. The structural and dielectric properties of specimens were investigated while varying the composition and sintering temperature(1,200~1,45$0^{\circ}C$) in order to obtain the optimum condition of capacitor. As is well known, Curie temperature(T$_{c}$) of high dielectric-based ceramic(BaTiO$_3$) was shifted and temperature of capacitance was decreased in according to increase of solid solution with (Sr, Mg)TiO$_3$. As a result, a suitable condition of compound rate for capacitor was obtained such as the BSM-11(0.8BaTiO$_3$-0.1SrTiO$_3$-0.1MgTiO$_3$), and sintering temperature was sintered at 1,25$0^{\circ}C$ for two hours. In this case, dielectric constant<1,300, dielectric loss(tan$\delta$)<0.03, and the variation rate of capacitance had less than 3% in the range -10~7$0^{\circ}C$.>.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.45-48
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• 1998

A BaTiO$_3$ was annexed to SrTiO$_3$, (x)BaTiO$_3$-(1-x)SrTiO$_3$ (0.7$\leq$X$\leq$1) ceramics with stable dielectric and electrical properties in high voltage were manufactured. Structural, dielectric and electrical properties were surveyed with the contents of SrTiO$_3$. The open porosity and sintering density were excellent in 0.9BaTiO$_3$-0.1SrTiO$_3$, the grain size of 0.9BaTiO$_3$-0.1SrTiO$_3$ was maximum at 12.40[${\mu}{\textrm}{m}$]. Increasing SrTiO$_3$ mol ratio, the curie temperature was shifted low temperature and the supreme permittivity was increased. In line with increasing of supplied voltage, permitivity was decreased slightly.

• Membrane Journal
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• v.22 no.1
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• pp.8-15
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• 2012

Tubular $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ membranes with $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$ porous coating layer were prepared by extrusion and dip coating technique. XRD and SEM result showed the tubular membrane possessed the perovskite structure and porouscoating layer (thickness= about $2{\mu}m$) in surface. The oxygen permeation test was measured at condition of ambient air (feed side) and vacuum (permeate side) in the temperature range from 750 to $950^{\circ}C$. The oxygen permeation flux of $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ tubular membrane with $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$ porous coating layer reached maximum $3.2mL/min{\cdot}cm^2$ at $950^{\circ}C$ and was higher than non-coated $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ tubular membrane. Long-term stability test result indicated that the oxygen permeation flux was quite stable during the 11 day.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.525-530
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• 2011

We investigated the electrical properties the starting material and sintering condition on the laminated PTC thermistor for micro circuit protection. The influences of $BaTiO_3$ powder with the 0.3 and 0.45 ${\mu}m$ size and the electrical characteristics (Ba,Sr)$TiO_3$ sintered at 1350~1400$^{\circ}C$ for 2 h in a reducing atmosphere (1% $H_2/N_2$). The sintered (Ba,Sr)$TiO_3$ was increased pore and the grain size was decreased according to increasing Sr additions. In relative permittivity, the phase transition temperature of (Ba,Sr)$TiO_3$ was decreased for 2.5$^{\circ}C$ according to increasing 0.01 mole Sr additions, and the phase transition dose not appeared about 0.3 mole Sr addition. The (Ba,Sr)$TiO_3$ was show the low resistance from 0.01 mole to 0.05 mole by Sr addition, regardless of sintering temperature. The (Ba,Sr)$TiO_3$ was show $10^2$ jump order at 0.1 and 0.2 mole Sr addition, and PTCR of the sintered $(Ba_{0.7}Sr_{0.3})TiO_3$ does not appeared about 0.3 mole Sr addition, regardless of the sintering temperature and starting material size.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.73-76
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• 2001

We deposited epitaxial $Ba_{0.6}Sr_{0.4}TiO_{3}(BST)$ films having thickness of 400 nm on MgO(001) substrates, where a 10 nm thick $Ba_{1-x}Sr_{x}TiO_{3}$ (x = 0.1 - 0.7) interlayer was inserted between BST and MgO to manipulate the stress of the BST films. Since the main difference of those epitaxial BST films was the lattice constant of the interlayers, we were very successful in controlling the stress of the BST films. BST films under small tensile stress showed larger dielectric constant than that without stress as well as those under compressive stress. Stress relaxation was investigated using epitaxial BST films with various thicknesses grown on different interlayers. For BST films grown on $Ba_{0.7}Sr_{0.3}TiO_{3}$ interlayers, the critical thickness was about 600 nm. On the other hand, the critical thickness of single-layer BST film was less than 100 nm.

• Journal of the Korean Ceramic Society
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• v.23 no.1
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• pp.27-32
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• 1986

This study is aimed at synthsizing high dielectric material (Ba, Sr)$TiO_3$ through direct wet process. Pure and ultra fine particle of (Ba, Sr)$TiO_3$ Powder was synthesized from $BaCl_2$ $SrCl_2$ and TiCl4 aqeous solution at KOH Solution in the $N_2$ gas atmosphere. $BaCl_2$ $SrCl_2$ and TiCl4 were Mixed with the mole ratio of 1:9, 3:7:10, 5:5:10, 7:3:10, 9:1:10 and sythesized at 4$0^{\circ}C$~9$0^{\circ}C$ for 10min~15hrs. The particle size particle shape crystallinity and synthesis condition of (Ba, Sr)$TiO_3$ powder with the variation of temperature and reaction time in the aqueous solution studied by the exprimental instruments of DTA. TGA, X-ray diffratometer SEM.

• Journal of the Korean Ceramic Society
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• v.36 no.7
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• pp.767-772
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• 1999

The effect of B2O3 addition on the sintering behavior dielectric and ferroelectric properties of Ba0.7Sr0.3TiO3 ceramics were investigated. The sample with 0.5wt% B2O3 was sintered under 115$0^{\circ}C$. The dielectric and ferroelectric properties of BST with 0.5wt% B2O3 was as good as BST without B2O3 sintered at 135$0^{\circ}C$ and its dielectric loss was even better When B2O3 was added over 1.0wt% the overdoped B2O3 remained in the specimens and formed a second phase which degraded the sintering behaivor dielectric properties of BST.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.795-797
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• 1998

A $BaTiO_3$, ferroelectric material, was mixed $SrTiO_3$, $(x)BaTiO_3-(1-x)SrTiO_3$($0.7{\leq}x{\leq}1$) ceramic capacitor with stable electrical properties in high voltage was fabricated. And microstructure, electrical property were investigated with $SrTiO_3$ mol ratio. The shrinkage, open porosity, sintering density were predominated at $9BaTiO_3-0.1SrTiO_3$. Increasing $SrTiO_3$ mol ratio, curie temperature was shifted at low temperature and maximum permittivity was increased. Also, $0.9BaTiO_3-0.1SrTiO_3$ was showed stable dielectric properties at $25{\sim}80[^{\circ}C]$. V-I properties of specimen were observed in the temperature range of $21{\sim}143[^{\circ}C]$, were divided into three regions. The region I below 10[kV/cm] was shown Ohmic conduction, the region II from 10 to 30[kV/cm] was explained by the Poole-Frenkel emission theory and the region III above 30[kV/cm] was analysed by the tunneling effect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.286-286
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• 2007

Li이 첨가된 0.7(Ba,Sr)$TiO_3$-0.3MgO 후막 interdigital 커패시터를 연구하였다. Li이 첨가된 0.7(Ba,Sr)$TiO_3$-0.3MgO의 후막을 $Al_2O_3$ 기판 위에 형성하기 위하여 스크린 프린팅 방법을 이용하였다. $BaSrTiO_3$의 세라믹 물질은 높은 유전율(1MHz에서 500이상)과 낮은 유전 손실(1MHz에서 0.01)값을 가지고 있는 반면, $1350^{\circ}C$의 높은 온도에서 소결되는 단점이 있다. 따라서 본 연구에서는 $BaSrTiO_3$ 세라믹 물질의 유전특성을 향상시키고 $1350^{\circ}C$의 높은 소결온도를 낮추기 위해서, MgO(30wt%)와 Li(3wt%)을 $BaSrTiO_3$에 첨가하였다. 그리고 10um의 후막을 $Al_2O_3$ 기판 위에 스크린 프린팅 방법을 통해 형성한 후, 50um finger gap의 interdigital 커패시터를 Ag 전극을 이용하여 제작하였다. 샘플을 제작하기 전에, Frequency와 유전율의 상관관계를 알아보기 위해 3D simulator를 통해 시뮬레이션 하였고, 주파수와 온도별 유전 특성, 구조와 전암-전류에 대한 특성을 본 연구의 결과를 통해 토의 할 것이다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.180-181
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• 2009

$(Ba_{0.6},Sr_{0.3}Ca_{0.1})TiO_3$ powders, which were prepared by sol-gel method using a solution of Ba-acetate, Sr-acetate and Ca-acetate and Ti iso-propoxide, $(Ba_{0.6},Sr_{0.3}Ca_{0.1})TiO_3$ array thick films doped with 0.1 mol% $MnCO_3$ and $Yb_2O_3$ (0.1~0.7 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 thickness of all (Ba,Sr,Ca)$TiO_3$ thick films was approximately 60mm. The Curie temperature of doped with 0.1 mol% $Yb_2O_3$ specimen was $45^{\circ}C$, and the dielectric constant and at this temperature was 1062.