• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.1
• /
• pp.151-159
• /
• 1998

Elelctrical properties of $BaTiO_3$ were characterized with addition of $Y_2O_3, CaO,SiO_2$ and Mn to develope the composition of PTC thermistor suitable as a current limiting device for automobile motor system. With the addition of 0.2 mol% $Y_{2}O_3$ to $BaTiO_3$, the minimum resistance of 16.5 ${\Omega}{\cdot}$cm was obtained at room temperature. $(Ba_{0.996}Y_{0.004})TiO_3$ exibited a minimum resistance of 50${\Omega}{\cdot}$cm with addition of 1.6 mol% $SiO_2$. The grain size of $(Ba_{0.996}Y_{0.004})TiO_3$ decreased from 34.95 ${\mu}$m to 13.4 ${\mu}$m and thus breakdown voltage could be improved by changing the composition as $(Ba_{0.996}Y_{0.004}Ca_{0.05}) TiO_3$ with substition of 5 mol% Ca into Basites. When 0.04 mol% Mn was added, the optimum PTCR properties could be obtained : the resistivity at room temperature and ${\rho}_{max}/{\rho}_{min}$ were 30~40${\Omega}{\cdot}$cm and $1.5{\times}10^5$ respectively.

• Journal of the Korean Ceramic Society
• /
• v.32 no.5
• /
• pp.567-574
• /
• 1995

The effect of MnO2 addition to 0.1mol% Sb2O3-doped BaTiO3 ceramics on microstructure and PTCR characteristics was studied. The PTCR characteristics was observed when 0.01 and 0.02 wt% MnO2 were added and sintered at 132$0^{\circ}C$ for 1 hour. The characteristics can be explained by the changes in the number and size of the abnormal grain growth due to the liquid phase during sintering. when the amount of MnO2 addition was 0.03 wt%, the sample showed NTCR characteristics with room-temperature resistivity over 109 Ωm regardless of the sintering temperature. This behavior can be described by the microstructure change due to the abnormal grain growth and charge compensation effect by MnO2 added. The room-temperature resistivity was increased as the amount of MnO2 was increased. And the specific resistivity ratio (pmax/pmin) showed maximum at 0.02wt% MnO2.

• Journal of the Korean Ceramic Society
• /
• v.24 no.6
• /
• pp.537-542
• /
• 1987

The microstructure and electrical properties of Pb[(Sb1/2 Nb1/2)0.08 Zr0.49 Ti0.48]O3 with MnO2 addition have been investigated in this work. The amount of MnO2 addition was 0, 0.4, 0.8, 1.2, 2.0 wt%, respectively. The soild solution range of MnO2 that assumed in this composition according to thevariations of micro-structure and electrical properties was 0.4-0.8 wt%.

• 한국전기화학회:학술대회논문집
• /
• 2002.07a
• /
• pp.117-122
• /
• 2002

고체산화물 연료전지의 구성요소인 양극(공기극)을 GNP와 Pechini 법을 이용하여 $(La{1-x}Sr_x)MnO_3$ 양극을 합성하여 합성한 분말의 특성과 단위전지로 사용하기 위한 조건에서의 특성을 측정하였다. GNP로 합성한 분말의 경우 직접 $(LaSr)MnO_3$ 단일 결정상을 얻을 수 있었으나, Pechini 법으로 합성한 분말의 경우는 비정질이었다. 또한 각각의 방법으로 합성한 분말의 입자형태는 구형이었고 1차상 입자크기는 GNP가 40nm, Pechini, 법으로 합성한 경우 20nm 정도의 크기를 갖고 있었다. GNP로 합성한 분말의 입자크기와 비표면적의 경우 glycine의 첨가량이 증가함에 따라 입자크기는 감소하였으나 최적 glycine 첨가량은 2.0mole 였고, 이 때 평균2차상의 입자크기는 $13.24{\mu}m$로 agglomeration 되어있었다. 최적 cathode조성은 GNP법으로 합성한 $(La_{0.9}Sr_{0.1}MnO_3$로서 가능하였고, 이 조성에서의 열팽창계수는 $9.89\times10^{-6}/^{\circ}C$이고, 전기전도도($1200^{\circ}C$에서 2시간소결)는 110 S/cm을 나타내었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.959-962
• /
• 2001

In this study, the piezoelectric and dielectric properties and Temperature stability of resonant frequency with MnO$_2$doped 0.36Pb(Sc$_{1}$2/Nb$_{1}$2/)O$_3$- 0.25Pb(Ni$_{1}$3/Nb$_{2}$3/)O$_3$-0.39PbTiO$_3$(hereafter PSNNT) were investigated. The tetagonality of crystal structure was developed with increasing MnO$_2$additive content. With increasing MnO$_2$additive content, the electromechanical coupling factor and quality factor were increased. Electromechanical coupling k$_{p}$ and quality factor Q$_{m}$ at MnO$_2$doped with 2.0mol% were showed highest value of 55.6% and 252. In the case of specimen for MnO$_2$doped with 2mol%, temperature dependance of resonant frequency had a good properties.ies.

• Journal of the Korean Ceramic Society
• /
• v.29 no.1
• /
• pp.60-64
• /
• 1992

In the ceramics of PFN-PFW system modified with MnO2 dielectric properties and the relation of its microstructure have been investigated. The amount of MnO2 variations was 0, 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3 mol%, respectively. In the result of the microstructure and electrical properties, the solid solution range of MnO2 was 0.15 mol%.

• Resources Recycling
• /
• v.11 no.5
• /
• pp.30-33
• /
• 2002

Recently in the progress of electronic equipment, power transformer was considered an important part. To make power transformer with miniaturization, lightening, low Power, we need a high efficiency core material. In this paper, we added $V_2$$O_{5}$ and $CaCo_3$ to Mn-Zn Ferrite to make a high efficiency, low loss core material. The compositions are MnO : ZnO : $Fe_2$$O_3$=37 : 11 : 52 mol%. They were sintered at 1250 for Three hours. Initial permeability was measured at 0.1 MHz. At 200 mT, Power loss was measured by temperature changing at 25 KHz, 50 KHz, 100 KHz. When we added $V_2$$O_{5}$ and $CaCo_3$, 0.08 wt%, 0.05 wt% respectively, we get 415 ㎾/㎥ at 200 mT, 100 KHz, $60^{\circ}C$. We can reduce eddy current loss as a main loss of high frequency by addition of a little mount of $V_2$$O_{5}$ $CaCo_3$. So we can decrease the power transformer's power loss.

• Journal of the Korean Electrochemical Society
• /
• v.14 no.3
• /
• pp.131-137
• /
• 2011

A simple and rapid electrochemical method for the quantitative analysis of $Mn^{2+}$ ion is demonstrated with a view to examine the $Mn^{2+}$ dissolution behavior of $LiMn_2O_4$. The method described herein is based on the oxidation reaction of $Mn^{2+}$ to $Mn^{4+}(MnO_2)$ in aqueous buffer solution. Under the optimum condition (pH 8.9 0.04 M $NH_3-NH_4Cl$ buffer solution and glassy carbon working electrode), the linear range of $5{\mu}M-100{\mu}M$ (0.275-5.5 ppm) [$Mn^{2+}$] is obtained for the Linear sweep voltammetry(LSV) and $0.2{\mu}M-10{\mu}M$ (0.011-0.55 ppm) [$Mn^{2+}$] for the differential pulse voltammetry (DPV), respectively. It is also noted that the oxidation reaction of $Mn^{2+}$ ion is reduced with increasing amount of the electrolyte ($LiPF_6$, EC, EMC) added to the measuring solution, which is found to be mainly due to $LiPF_6$ and EC rather than EMC.

• Journal of the Korean Magnetics Society
• /
• v.5 no.3
• /
• pp.197-202
• /
• 1995

고주파용 전원의 필요성이 대두되면서 고주파에서 낮은 자기손실을 가진 재료의 개발이 요구되고 있다. Mn-Zn 페라이트의 자기손실은 전기비저항의 증거나 소결시 미세구조의 제어로 줄일 수 있다. 본 연구에서는 연쇄고온합성법(Self-propagation High- temperature Synthesis)에 의해 제조된 $_Mn_{0.72}$Z $n_{0.22}$)$_{0.94}$ (F $e_{2}$ $O_{3}$)$_{1.06}$ 조성의 Mn-Zn페라이트에서 첨가물이 미세구조와 자기적 성질에 미치는 영향에 대해 조사하였다. $SiO_{2}$와 Ca $Co_{3}$의 복합첨가에 의해 미세구조의 미세화와 아울러 낮은 자기손실 특성을 얻을 수 있었다. 그러나 첨가 물의 과다 첨가시에는 비정상입자성장 조직이 나타났으며 자기적 성질이 현저히 저하 하였다. 전기비저항, 자기손실의 주파수 의존 결과에 근거하여 주된 자기손실기구 및 이에 미치는 첨가물 효과에 대해 논하였다.

• Electrical & Electronic Materials
• /
• v.10 no.1
• /
• pp.33-38
• /
• 1997

The green emitting phosphors of the Field Emission Display(FED), Al codoped ZnGa$_{2}$O$_{4}$:Mn, were synthesized and sintered at high temperature. From X-ray diffraction measurements, it was confirmed that poly crystalline ZnGa$_{2}$O$_{4}$ and ZnAI$_{2}$O$_{4}$ solid solution coexist in Al codoped ZnGa$_{2}$O$_{4}$:Mn. Photoluminescence spectra of Al codoped ZnGa$_{2}$O$_{4}$:Mn show that the main peak position is shifted from 504 nm to 513 nm with the increase of Al concentration. The brightness was improved with the amount of Al dopant. It showed the maximum value at the doping level of 0.03 mole and then, it degraded rapidly. These results are due to the superposition of emission from . ZnGa$_{2}$O$_{4}$:Mn and ZnAI$_{2}$O$_{4}$:Mn.