• Journal of the Korean Society for Heat Treatment
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• v.27 no.1
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• pp.23-26
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• 2014

Ga doped ZnO (GZO) single layer and GZO/ZnO bi-layered films were deposited on glass substrates by radio frequency magnetron sputtering and then the influence of film thickness on the structural, electrical, and optical properties of the films was considered. Thicknesses of the GZO/ZnO films was varied as GZO 100 nm, GZO 85 nm/ZnO 15 nm and GZO 70 nm/ZnO 30 nm, respectively. The observed result means that optical transmittance and electrical resistivity of the films were influenced with film thickness and GZO 85 nm/ZnO 15 nm bilayered films show the higher figure of merit than that of the films prepared other films in this study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.126-129
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• 2003

The electrical properties of a ZnO-based multilayered chip varistor (abbreviated as MLV) were studied as functions of firing condition and the degree of lamination. The fundamental varistor characteristics such as nonlinear coefficient and breakdown voltage were independent of the degree of lamination. As the number of the laminated ceramic sheets increased, however, not only the energy handling capability but also the capacitance and the leakage current which are relevant to delayed response to the voltage surge and the pre-breakdown energy loss, respectively, increased. With the increase of firing temperature between $950^{\circ}C$ and $1150^{\circ}C$, both the capacitance and the leakage current of the MLV increased due mainly to the grain growth of ZnO and the volatilization of $BiO_2O_3$. High performance MLVs with clear electrode pattern were obtained at the firing temperature range of $l000{\sim}1050^{\circ}C$ in this experiment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.100-100
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• 2009

ZnO 바리스터는 정전기 및 순간적인 surge로부터 전자기기 및 전자회로 등을 보호하기 위해 개발된 전자 세라믹스 소재이다. 최근 전자기기 등의 고속통신 추세에 따라 ZnO 바리스터는 높은 비선형 특성과 함께 보다 낮은 유전율 및 유전손실 특성이 특별히 요구되고 있다. 따라서 본 연구에서는 현재 양산되고 있는 Bi-계와 Pr-계 ZnO 바리스터가 아닌 새로운 조성계를 이용하여 Y 첨가량(0.1~3.0 at%)에 따른 ZnO 바리스터의 전기적 특성과 유전 특성을 살펴보았다. 시편은 일반적인 세라믹 공정에 따라 제조하여 $1200^{\circ}C$에서 3 시간 공기 중에서 소결하였으며, 소결 및 전기적 특성과 유전 특성(밀도, 미세구조, I-V 특성, 유전율, 유전손실, ZnO grain 비저항)은 FE-SEM, Keithley237, Agilent 4294a 및 Agilent 4991a 장비를 사용하여 Y 함량에 따른 ZnO 바리스터의 특성 변화를 고찰하였다. 그 결과, Y이 2.0 at% 첨가한 계의 바리스터 특성이 가장 우수하였다. 보다 구체적으로 살펴보면 다음과 같다. Y 함량이 증가함에 따라 상대밀도는 94~96%로 증가하였으며, 평균입경은 증가하였다. 또한 유전율은 580~215 (at 1 MHz)로 Y 함량이 증가할수록 낮아졌다. 이를 통하여 새로운 바리스터 조성계에서 Y의 첨가 효과에 대하여 논하였다.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1460-1462
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• 2001

초고속 전력선 통신을 위한 고주파수 대역에서 안정적인 자기적 특성을 갖는 Ni-Zn ferrite를 개발하기 위해서 투자율은 낮지만 주파수 특성이 우수한 $Ni_{0.8}Zn_{0.2}Fe_2O_4$를 기본조성으로 입자를 성장시키는 $Bi_2O_3$를 0.7, 비저항을 증가 시키는 CaO를 0.3, 그리고 입자를 균일하게 하는 $V_2O_5$를 0.1 wt% 첨가하여 미세구조를 제어하고, 다시 고주파 특성을 향상시킬 것으로 기대되는 $Co_3O_4$를 0, 0.3, 0.5, 0.7 wt%로 변화시켜 자기적 특성을 조사하였다. $Co_3O_4$가 밀도 및 미세구조에는 영향을 미치지 않았으나 0.3, 0.5 wt% 첨가시 첨가하지 않은 조성보다 투자율은 감소하였으나 사용 한계 주파수로 여겨지는 공명주파수가 각각 19.905, 19.205 MHz로 크게 증가하였다. 그리고 전체 전력 손실도 $Co_3O_4$를 첨가했을 때 감소하였으나 첨가량에는 큰 변화가 없었다. 와전류 손실이 전체 전력손실에 지배적인 영향을 미치고 있다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.200-207
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• 2011

Abstract: The effect of lead free glass frit compositions on the properties of thick film conductor and resistor pastes were investigated. Two types lead free frits, HBF-A(without $Bi_2O_3$) and HBF-B(with $Bi_2O_3$) were made from $SiO_2$, $B_2O_3$, $Al_2O_3$, CaO, MgO, $Na_2O$, $K_2O$, ZnO, MnO, $ZrO_2$, $Bi_2O_3$. And Ag based conductor pastes and $RuO_2$ based resistor paste were prepared by mixed with these frits and functional phase(Ag and $RuO_2$), and organic vehicle. The properties of thick film conductor and resistor sintered at $850^{\circ}C$ were studied after printing on $Al_2O_3$ substrate. The morphology of the sintered films surface were SEM and EDS were carried out to analysis the chemical composition on resistor surface and state of Ru atom in frit matrix.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.30-36
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• 2002

The effects of the sintering additives such as B $i_2$ $O_3$ and $V_2$ $O_{5}$ on the microwave dielectric and sintering properties of ZnTi $O_3$ system were investigated. Highly dense samples were obtained for ZnTi $O_3$ at the sintering temperature range of 870~90$0^{\circ}C$ with B $i_2$ $O_3$ and $V_2$ $O_{5}$ additions of <1 wt.%, respectively. The microwave dielectric properties of ZnTi $O_3$ with 0.6 wt.% B $i_2$ $O_3$ and 0.5 wt.% $V_2$ $O_{5}$ were as follows: Qx $f_{o}$ = 48,400 GHz, $\varepsilon$$_{r}$= 22, and $\tau$$_{f}$ = -43 ppm/$^{\circ}C$. In order to improve temperature coefficient of resonant frequency, Ti $O_2$ was added to the abode system. The optimum amount of Ti $O_2$was 15 mol.% when sintered at 87$0^{\circ}C$, at which Ive could obtain following results: Qx $f_{O}$ = 44,700GHz, $\varepsilon$$_{r}$ = 26, and $\tau$$_{f}$ = 0 PPm/$^{\circ}C$.>.EX>.>.>.EX>.>.>.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.203-204
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• 2006

Nano-Varistors fabricated with ZnO 30nm and 80nm powders were studied about the electrical characteristics with AC accelerated degradation in this paper Especially, ZnO nano-powder varistors were sintered m air at $1050^{\circ}C$ and analyzed the phenomenons of before and after AC degradation test. The stress conditions of AC degradation test were $1.0V_{1mA}$ $115{\pm}2^{\circ}C$ for 24h. 80nm-varistor was exhibited better performance than 30nm-varistor m the electrical stabilities. And then 80nm-varistor resulted m the degradation characteristics that the variation rate of operating voltage, nonlinear coefficient and leakage current was -0 3%, -0 4% and -3 3%, respectively.

• Proceedings of the KIEE Conference
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• 2008.05a
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• pp.199-200
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• 2008

ZnO을 주원료로 하고 첨가제로 $Bi_2O_3$, $Sb_2O_3$, $Nd_2O_3$, CoO, $Cr_2O_3$, $MnO_2$, NiO를 고정한 후 $Y_2O_3$ 첨가량에 바리스터의 전기적 특성을 검토하였다. $Y_2O_3$ 첨가량이 증가할 수록 바리스터 전압이 직선적으로 증가함을 확인할 수 있으며 결정립계에 존재하는 스핀넬상에 $Y_2O_3$가 이차상으로 존재함을 확인 할 수 있었다. $Y_2O_3$ 첨가에 따라 ZnO 결정입자 성장을 방해하여 바리스터 전압을 증가시키는 반면 결정립의 크기를 불균일하게 하여 유전율을 감소시키고 유전손실은 증가함을 확인하였다. 본 연구 결과 $Y_2O_3$ 첨가로 바리스터 전압은 350 V/mm이상을 얻을 수 있으며 누설전류를 $1{\mu}A$이하로 하는 조성을 얻을 수 있었으며 소형 바리스터 제작이 가능함을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.275-279
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• 1998

The influence of $WO_3$ (0.5-4.0mol%) on the microstructural and electrical properties of ZnO varistors was investigated. The major part of a tungsten segregated to the nodal point. SEM, EDAX, and XRD analysis revealed that three phase, such as W-rich phase, Bi-rich phase, and spinel phase, coexist at the nodal point. The average grain size increased in the range of 15.5-29.9pm with increasing $WO_3$ content. This may be probably attributed to liquid phase formed by $WO_3$, $WO_3$ acted as promotion additive of grain growth. As $WO_3$ content increase, the varistor voltage greatly decreased in the range 186.82-35.87V/mm due to the increase of grain growth. The barrier height decreased in the range 1.93-0.42eV with increasing $WO_3$content.

• Journal of the Korean Ceramic Society
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• v.39 no.5
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• pp.438-445
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• 2002

In this study, the glass frit of $PbO-TiO-2-SiO_2-BaO-ZnO-Al_2O-3-CaO-B_2O_3-Bi_2O_3-MgO$ system was manufactured. The glass was melted at $1,400{\circ}C$, quenched and attrition-milled. The glass frit powder was pressed and fired for 2h at the range of $750~1,000{\circ}C$. The crystallization of glass frit began at about $750{\circ}$ and at low temperature, the main crystal phases were hexagonal celsian($BaAl_2Si_2O_8$) and alumina. As the firing temperature increased, the crystal phases of monoclinic celsian, zinc aluminate, zinc silicate, calcium titanium silicate and titania appeared. And the increase of firing temperature led to transformation of hexagonal celsian to monoclinic. The only glass frit containing 15wt% PbO had the crystal phase of solid solution of $PbTiO_3-CaTiO_3$. At the frequency of 1 MHz, the dielectric constant of glass frit crystallized was in the range of 11~16 and the dielectric loss less than 0.020. But the glass frit containing 15wt% PbO had the dielectric constant of 17~26 and loss of 0.010~0.015 because of crystal phase of solid solution of $PbTiO_3-CaTiO_3$.