• 한국세라믹학회지
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• 제24권1호
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• pp.63-69
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• 1987

Effect of MoO3 additiion on the semiconductive BaTiO3 ceramics doped with 0.2 mole% Nb2O5 and their frequency characteristics have been investigated on the view of intergranular barrier layer model through the observation of changes in their electrical properties. The resistivity increases with the increase of MoO3 addition, but the capacitance, the frequency dependence of capacitance and the effect of positive temperature coefficient of resistivity (PTCR) decrease. It is explained by the possible increase in the thickness of potential barrier due to the formation of insulating layer and thus decrease in the degree of energy band bending. Both the PTCR effect and resistivity decrease with the increase of frequency due to the possible elimination of barrier layer at the grain boundary.

• 대한전기학회논문지
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• 제43권3호
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• pp.528-531
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• 1994

Digitalization in electronic system is required the capacitor which have a large capacitance with small size, low impedance at high frequency, and high reliability. The fabrication and its properties of aluminum solid electrolytic capacitor are investigated. Employing conduction polymer film such as, polypyrrole as solid electroylte, solid type aluminum electrolytic capacitors were made. The surface of insulationg oxide is covered with conducting polymer layer prepared by chemical oxidative polymerization. Thereafter this conducting layer is covered with conducting polymer prepared by electrochemical polymerization. The dielectric properties of these capacitors were also measured and discussed. Regarding on frequency characteristics of the trial made capacitor, impedance and ESR at high frequency is lower than those of the stacked type film capacitor. It is alo confirmed that temperature coefficient of capacitance and dissipation factor of the capacitor are lower than those of film capacitor and liquid type aluminum electrolytic capacitor.

• 한국세라믹학회지
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• 제24권3호
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• pp.270-276
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• 1987

The microstructure and dielectric properties of a SrTiO3-based GBL (Grain Boundary Layer) capacitor were investigated. The 0.6 mol% Nb2O5 doped SrTiO3 was sintered for 3 hr at 1450$^{\circ}C$ in mixed gas(N2/H2) atmosphere. The Nb2O5 promoted the grain growth of the SrTiO3 ceramics was decreased with the amount of Nb2O5. The oxide mixture(PbO, Bi2O3, B2O3) were painted on the reduced specimen and fired at 1000$^{\circ}C$ to 1100$^{\circ}C$ in air. The penetrated oxide mixture into specimen were located in grain boundaries. A SrTiO3-based GBL capacitor had the apparent permittivity of about 3.0${\times}$104, the dielectric loss of 0.01-0.02, and insulating resistance of 108-109$\Omega$.cm. The capacitor had the stable temperature coefficient of capacitance and exhibited dielectric dispersion over 107 Hz. The capacitance-voltage measurements indicated that the grain boundary was composed of the continuous insulating layers.

• 한국전기전자재료학회논문지
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• 제35권5호
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• pp.445-451
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• 2022

Ultrasonic sensor is suitable as a next-generation autonomous driving assist device because its lower price compared to that of other sensors and its sensing stability in the external environment. Although Pb(Zr, Ti)O₃ (PZT)-relaxor ferroelectric system has excellent piezoelectric properties, the change in capacitance is large in the daily operating temperature range due to the low phase transition temperature. Recently, many studies have been conducted to improve the temperature stability of ferroelectric ceramics by controlling the grain size and crystal structure, so it is necessary to study the effect of the grain size on the piezoelectric properties and the temperature stability of PZT-relaxor ferroelectric system. In this study, the piezoelectric properties, phase transition temperature, and temperature coefficient of capacitance (TCC) of 0.9 Pb(Zr_1-xTi_x)O₃-0.1 Pb(Zn_1/3Nb_2/3)O₃ (PZT_x-PZN) ceramics with various grain sizes were investigated. PZT_x-PZN ceramics with larger grain size showed higher piezoelectric properties and temperature stability, and are expected to be suitable for ultrasonic devices in the future.

• Transactions on Electrical and Electronic Materials
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• 제10권3호
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• pp.80-84
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• 2009

The microstructure, voltage-current, capacitance-voltage, and dielectric characteristics of CCT doped Zn/Pr-based varistors were investigated at different sintering temperatures. As the sintering temperature increased, the average grain size increased from 4.3 to 5.1 ${\mu}m$ and the sintered density was saturated at 5.81 g $cm^{-3}$. As the sintering temperature increased, the breakdown field decreased from 7,532 to 5,882 V $cm^{-1}$ and the nonlinear coefficient decreased from 46 to 34. As the sintering temperature increased, the donor density, density of interface states, and barrier height decreased in the range of (9.06-7.24)${\times}10^{17}\;cm^{-3}$, (3.05-2.56)${\times}10^{12}\;cm^{-2}$, and 1.1-0.95 eV, respectively. The dielectric constant exhibited relatively low value in the range of 529.1-610.3, whereas the $tan{\delta}$ exhibited a high value in the range of 0.0910-0.1053.

• 한국전기전자재료학회논문지
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• 제21권5호
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• pp.440-446
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• 2008

To manufacture the MLCC with X7R for high voltage stability, $BaTiO_3-MgO-MnO_2-Y_2O_3$ with $(Ba_{0.4}Ca_{0.6})SiO_3$ glass frit was formulated. Based on this composition, the addition of $Er_2O_3$ showed that TCC(Temperature Coefficient Capacitance) at $85^{\circ}C$ was improved from 5 % to ${\sim}0\;%$, but the dielectric constant and IR (Insulation Resistance) were decreased. The glass frit improved the dielectric constant and IR, so the appropriate contents of $Er_2O_3$ and glass frit were 0.6 mol% and 1 wt%, respectively. It showed that the dielectric constant and RC constant were 2,550 and 2,000 (${\Omega}F$), respectively in the sintering condition at $1250^{\circ}C$ in PO2 $10^{-7}$ Mpa. The MLCC with $3.2{\times}1.6$ (mm) size and $1\;{\mu}F$ was also suited for X7R with the above composition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1516-1519
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• 1996

In this paper, a study on the electrical properties of ternary compound ceramics $[(1-y-x)BaTiO_{3}-ySrTiO_{3}-xMgTiO_3]$ fabricated 7 samples with each mol[%] by using the mixed oxide method. In this case, the sintering temperature were at $1,250[^{\circ}C]$ for 2[hr]. Also made ceramic capacitors from 7 samples, temperature coefficient of the capacitance and the variation of relative dielectric constants and loss with fixed frequency (1KHZ) were studied. In some ceramic capacitors, has shown very good properties of the dielectric constants and loss. In case of BSM-11 ceramic capacitor, is sure to the commercial capacitor which shows steady properties.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 추계학술대회 논문집
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• pp.8-11
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• 1988

(1-x-y)Pb($Zn_{1/3}Nb_{2/3})0_3-BaTiO_3PbTiO_3(0.05{\leq}x{\leq}0.20, 0.05{\leq}y{\leq}0.15$) ternary compound ceramics were fabricated by the mixed oxide method. The dielectric properties with temperature and frequency of the specimens were investigated. Relative dielectric constants of the specimens were increased with $BaTiO_3$ contents. Increasing the $BaTiO_3$contents, the variation in the relative dielectric constant with frequency, the temperature coefficient of capacitance (TCC) and the dielectric loss were decreased.

• 한국결정성장학회지
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• 제19권2호
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• pp.102-105
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• 2009

$BaTiO_3$ 입자 크기가 MLCCs의 절연 특성 및 MLCCs 특성 열화에 미치는 영향을 알아보기 위해 서로 다른 입자를 사용하여 제작한 MLCCs의 가속열화시험을 $150^{\circ}C$, 75 V조건에서 실시하였다. 실험에 사용된 MLCCs는 각각 $0.525{\mu}m$, $0.555{\mu}m$, $0.580{\mu}m$의 입자 크기를 가지는 $BaTiO_3$와 Ni계 전극을 사용하여 상용화된 공정을 통해 제조되었다. 제조된 MLCCs에 대해 정상 유무 확인을 위해 X5R조건 하에서 TCC(Temperature Coefficient of Capacitance) 측정을 통해 유전 변화율에 대해 알아보았다. 세 가지 입자 크기에 따른 절연저항의 거동을 알아보기 위해 BDV(Breakdown Voltage)를 실시하였고, 가속열화시험 후 입자의 크기에 따른 MLCCs 열화의 정도와 원인을 알아보기 위해 XPS(If-ray photoelectron spectroscopy)를 통해 고장분석을 하였다. $BaTiO_3$의 입자 크기가 작을수록 절연파괴저항 및 절연저항 열화에 우수한 특성을 나타내었고, XPS 분석 결과 확인된 NiO peak과 $BaTiO_3$ peak 감소를 통해 MLCCs 열화원인이 유전체의 산소 환원과 환원된 산소와 전극간 반응임을 알 수 있었다.

• 한국전기전자재료학회논문지
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• 제29권7호
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• pp.404-407
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• 2016

In this study, to develop low temperature sintering capacitor composition ceramics with the good dielectric properties, $(Ba_{0.86}Ca_{0.14})(Ti_{0.85}Zr_{0.12}Sn_{0.03})O_3$ (BCTZ) ceramics were prepared by the conventional solid-state reaction method. The effects of $B_2O_3$ addition on the dielectric properties and microstructure was investigated. The XRD patterns demonstrated that all the specimens showed Perovskite phase, and secondary phases are indicated in the measurement range of XRD. And also, temperature coefficient of capacitance(TCC) of all the specimen sintered at $1,180^{\circ}C$ showed +3~-56% except for x=0.006. For all the specimens, observed one peak was tetragonal cubic difuse phase transition temperature(Tc), which is located in the vicinity of room temperature.