• 한국세라믹학회지
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• 제49권1호
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• pp.100-104
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• 2012

Barium zincoborate (BZB) glass was added to $Ba_{0.5}Sr_{0.5}TiO_3$, and sintered at $875^{\circ}C$ for 2 h in air. When the BZB glass was added in quantities ranging from 15 to 20 wt%, the relative bulk density ranged from 93.1% to 94.2%, while the density decreased to roughly 81% thereafter up to 30 wt% glass addition. Quantitative XRD analysis showed that the $Ba_{0.5}Sr_{0.5}TiO_3$ filler was significantly dissolved into the BZB glass. However, no secondary phase was identified by XRD up to 30 wt% glass addition. The dielectric constant was about 130 to 140 at 1MHz up to 20 wt% BZB glass addition, while it decreased to about 60 thereafter, which may be ascribed to decreased density, partial dissolution of the $Ba_{0.5}Sr_{0.5}TiO_3$, and associated changes in the glass composition. The dielectric loss of the 20 wt% glass added specimen was 0.008.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.104-104
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• 2003

RF magnetron sputtering 법을 이용하여 LaA1O$_3$, SrTiO$_3$, MgO 단결정 기판 위에 BaTiO$_3$ 박막을 에피텍셜하게 증착하여 박막의 특성과 마이크로 웨이브에서의 유전특성을 평가하였다. 각 기판위에 증착한 박막의 격자상수와 FWHM을 조사하였고, pole figure로 에피텍셜 성장을 관찰하였다. 각 시편에 상부 전극으로 interdigital 타입의 전극을 photolithography 하여 캐패시턴스와 tan $\delta$을 조사하였다. 각 기판의 변화에 따른 격자상수 변화와 유전 특성의 변화를 고찰하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.251-254
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• 1998

The ($0.8BaTiO_3-0.1SrTiO_3-0.1MgTiO_3$)+$0.006Nb_2O_5$ ceramics were fabricated by conventional ceramic process. The dielectric property of specimen was investigated that the specimen was sintering temperature at 1,300C for 3hours and then annealed at $1,100^{\circ}C$ for 3hours in a atmosphere (air) to be painted on the surface with CuO paste. The results of the temperature and frequency are varied, the dielectric constant and loss tangent are unsuitable for BL capacitor. The dielectric constants were varied to be negative temperature coefficient(2.000-3,000) in the temperature range between -10 and $140^{\circ}C$, the dissipation factors (tan $\delta$) were some high(0.1-0.3). It was not grain insulation, in cause of the some difficult to be annealed temperature with CuO paste and fired atmosphere. But, we have some different annealing temperature and fired atmosphere, it will be suitable BL(Boundary Layer)capacitor.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.565-568
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• 2004

An alkoxide-based sol-gel method was used to fabricate $Ba_{0.6}Sr_{0.4}TiO_3$ thin films doped by Bi from 5 to 20 mol% on a Pt/Ti/SiO2/Si substrate. The structural and dielectric properties of BST thin films were investigated as a function of Bi dopant concentration. The dielectric properties of the Bi doped BST films were strongly dependent on the Bi contents. The dielectric constant and dielectric loss of the films decreased with increasing Bi content. However, the leakage current density of the 10 mol% Bi doped $Ba_{0.6}Sr_{0.4}TiO_3$ thin film showed the lowest value of 5.13 10-7 at 5 V. The figure of merit (FOM) reached a maximum value of 32.42 at a 10 mol% Bi doped $Ba_{0.6}Sr_{0.4}TiO_3$ thin films. The dielectric constant, loss factor, and tunability of the 10 mol% Bi doped $BBa_{0.6}Sr_{0.4}TiO_3$ thin films were 333,0.0095, and 31.1%, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.60-60
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• 2008

We manufactured Liquid Crystal Polymer (LCP) and (1-x)$BaTiO_3-xSrTiO_3$(BST) ceramic composites and investigated dielectric properties to use as embedded capacitor in printed circuit boards and replace LTCC substrates. The dielectric properties of these composites are varied with volume fraction of BST and ratios of BT/ST. Dielectric constants are in the range of 3~28. In addition, we could get low TCC and High Q value that could not achieve in other ceramic-polymer composites. Especially, in composite with x=0.4 and 50vol% BST, the dieletric constant and Q-value are 27 and 300, respectively. And more TCC is -116~145ppm/$^{\circ}C$ in the temperature range of -55~$125^{\circ}C$. We think that this composites can be used high-Q substrate material like LTCC and embedded temperature compensation capacitor in printed circuit boards.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.123-126
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• 2001

The $0.98MgTiO_3-0.02BaTiO_3$ ceramics were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature and composition ratio by XRD, SEM and EDS. According to the X-ray diffraction patterns of the $0.98MgTiO_3-0.02BaTiO_3$ ceramics, the hexagonal $BaMg_6Ti_6O_{19}$ and ilmenite $MgTiO_3$ structures were coexisted. The dielectric constant$({\varepsilin}_r)$ and quality factor$(Q{\times}f_r)$ were decreased with increasing the sintering temperature in the range of $1275^{\circ}C{\sim}1350^{\circ}C$. In the case of the $0.98MgTiO_3-0.02BaTiO_3$ ceramics sintered at $1275^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 20.27, 76,845, $-46.6ppm/^{\circ}C$, respectively.

• 한국세라믹학회지
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• 제31권6호
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• pp.587-594
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• 1994

(Ba, Sr)TiO3-based PTCR ceramics were sintered and cooled down with various cooling conditions in the air. AES was applied to investigate the composition change in the grain boundary and bulk area of oxidatively cooled samples. Ba component was deficit in grain boundary region, while oxygen was abundant than bulk region. The discrete changes of oxygen binding energies were confirmed in the grain boundary region of the heavily oxidized samples. It was supposed that the large binding energy shift resulted from the oxidation of the segregated Mn in grain boundary region and this idea was supported by the DV-X$\alpha$ molecular energy simulation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
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• pp.103-106
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• 2002

The applicability of models based on fractal morphology to characterize $(Ba\;Sr)TiO_{3}$ thin film surfaces was investigated. The fractal morphology of coated barium strontium titan oxide thin film surfaces was described using fractal dimension from scanning electro microscopy image. The $(Ba\;Sr)TiO_{3}$ coating were deposited on silicon wafers using $(Ba\;Sr)TiO_{3}$ solution and spin coater. BST solution was composited by mol ratio, and then spin-coated from 3 times to 5 times coating on $Pt/SiO_{2}/Si$ substrate. Qualitative thin film analysis was performed with scanning electro microscopy (SEM), and surfaces parameters such as average grain diameter, roughness exponent and fractal dimension were determined.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권8호
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• pp.392-398
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• 2006

The properties of tunable dielectric materials on RF frequency band are important high tunability and low loss for RF variable devices, variable capacitor, phased array antenna and other components application. Various composite of BST(barium strontium titanate) ratio combined with other non-electrical active oxide ceramics have been formulated for such uses. We present the tunable properties and Curie temperature on BST thick films. The grain growth of the weight ratio of $BaTiO_3$ increased. This can be explained by the substitute $Sr^{2+}$ ion for $Ba^{2+}$ ion in the $BaTiO_3$ system. The Curie temperature was shifted to lower temperature with increasing $SrTiO_3$in the $BaTiO_3-SrTiO_3$ system, because of decreasing the lattice constant. Also, the dielectric constant, tunability and K-factor of $(Ba_xSr_{1-x})TiO_3$ at over the Curie temperature decreased, at over the $60^{\circ}C$ fixation, maximum dielectric constant at Curie temperature and hence sharper phase transformation occurred at Curie temperature. The result were interpreted as a process of internal stress relaxation resulting form the increase of $90^{\circ}$ domains induced the BST. As a result, It is concluded that over the Curie temperature, frequency response and DC field effect for the tunable properties of BST thick film are suppressed by the transition broadening. For the application of tunable devices, that the curie temperature was investigated to be increased.

• 청정기술
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• 제23권1호
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• pp.95-103
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• 2017

본 연구는 비 $TiO_2$ 계 광촉매 중 가장 널리 알려져 있는 $ATiO_3$ (A = Ca, Sr, Ba) perovskite를 sol-gel 법을 이용해 합성하였고, 골격치환이 용이한 점을 이용해 A site에 Ni을 첨가한 입자를 합성하였다. 합성한 $ATiO_3$와 Ni-$ATiO_3$ 입자의 불리화학적 특성은 X-선 회절분석(XRD), 자외선-가시선 분광광도계(UV-visible spectroscopy), 주사전자현미경 (SEM), 에너지분산형 분광분석법(EDS), 질소 등온 흡 탈착실험, X선 광전자분광법(XPS)을 이용해 확인하였다. 수소제조는 메탄올을 광분해하여 얻었으며, $ATiO_3$ 보다 Ni-$ATiO_3$ 촉매에서 높은 수소발생량을 나타내었다. 특히 Ni-$SrTiO_3$ 촉매를 사용하였을 때 24시간 반응 후 $273.84mmolg^{-1}$의 수소가 발생하였다. 또한 Ni-$SrTiO_3$ 촉매는 물(0.1 M KOH)을 분해하였을 때에도 높은 수소 제조 성능을 나타냈으며, 24시간 반응 후 $961.51mmolg^{-1}$의 수소가 발생한 것을 확인하였다.