• 한국전기전자재료학회논문지
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• 제20권2호
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• pp.124-129
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• 2007

Dielectric and piezoelectric properties of $0.57Pb(Sc_{1/2}Nb_{1/2})O_{3}-0.43PbTiO_{3}$, which is the morphotropic phase boundary composition for the PSN-PT system, were investigated as a function of $Fe_{2}O_{3},\;Nb_{2}O_{5}\;and\;MnO_{2}$ addition 0 wt% to 0.9 wt%. The maximum dielectric constant of ${\varepsilon}_{33}/{\varepsilon}_{o}=2054$ and the minimum dielectric loss of $tan{\delta}=0.37\;%$ at room temperature were obtained at 0.1 wt% of $Fe_{2}O_{3}$ and 0.5 wt% of $MnO_{2}$ addition, respectively. With addition of 0.5 wt% $Nb_{2}O_{5}$ and $0.5\;wt%\;MnO_{2}$, the electromechanical coupling factor $k_{p}$ and mecanical quality factor $Q_{m}$ were significantly increased, respectively. The maximum electromechanical coupling factor $k_{p}=61.5\;%$ was obtained by addition of $Nb_{2}O_{5}$ and high mechanical quality factor $Q_{m}=919$ was obtained by addition of $MnO_{2}$. The $Q_{m}(=919)$ value is 3.3 times larger than that of non-doped 0.57PSN-0.43PT ceramics.

• 한국자기학회지
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• 제9권3호
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• pp.149-153
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• 1999

SiO2-CaO-V2O5 3원계 첨가물을 함유한 Mn-Zn 페라이트 저손실의 주파수 및 온도 의존성에 대해 조사하고 주된 자기손실기구에 대해 고찰하였다. 연쇄고온합성법에 의해 MnO:ZnO:FeO=36:11:53mol% 조성의 페라이트를 제조하였다. 자기손실의 주파수 의존 결과로부터 저주파에서는 자기이력손실이 고주파에서는 와전류손실이 지배적임을 제시하였고, 고저항 첨가제에 의해 비저항이증가할수록 자기이력손실이 감소하였다. 순수 Mn-Zn 페라이트의 경우 자기 손실은 온도 증가에 따라 증가하였으나, 입계저항제가 첨가된 시편의 경우 와전류손실의 감소로 약 4$0^{\circ}C$에 서 자기손실의 최소치가 나타났다.

• 한국전기전자재료학회논문지
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• 제27권6호
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• pp.361-366
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• 2014

$MnO_2$-doped $0.985[Li_{0.04}(Na_{0.545}K_{0.46})_{0.96}(Nb_{0.81}Ta_{0.15}Sb_{0.04})]O_3+0.015KNbO_3(0.985LNKNTS+0.015KNbO_3)$ lead-free ceramics were fabricated by conventional solid state method to develop excellent dielectric and piezoelectric properties. The result of X-ray diffraction patterns obviously indicated that all of the specimen has pure perovskite structure without secondary phase. In addition, orthorhombic phase and coexistance region of orthorhombic-tetragonal phase (MPB) were observed with amount of $MnO_2$. The optimal values of ${\rho}$=4.70 $g/cm^3$, $d_{33}=238$ pC/N, $k_P=0.46$, $Q_m=121$, ${\varepsilon}_r=849$, and $T_C=225^{\circ}C$ were obtained at 0.01 mol% $MnO_2$ doped $0.985LNKNTS+0.015KNbO_3$ ceramics sintered at $990^{\circ}C$ for 5 h, respectively. Hence, it was indicated that the suitable amount of $MnO_2$ could improve the electrical properties of $0.985[Li_{0.04}(Na_{0.545}K_{0.46})_{0.96}(Nb_{0.81}Ta_{0.15}Sb_{0.04})]O_3+0.015KNbO_3$ ceramics.

• 한국재료학회지
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• 제2권1호
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• pp.12-18
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• 1992

등온용량과도분광법(Isothermal Capacitance Transient spectroscopy)을 이용하여 ZnO 바리스터의 포획준위를 결정하였다. 여기서 등온용량과도분광기는 YHP 4192A 임피던스 Analyzer와 데이터해석을 위한 개인용 컴퓨터로 구성된다. 이 실험에서 우리는 $ZnO-Bi_2O_3$에 MnO 및 CoO를 첨가한계에서 $-40^{\circ}C~60^{\circ}C$ 온도범위에서 0.28, 0.48, 0.50, 0.94eV 등의 입계포획준위가 존재함을 볼 수 있었다. 또한, $ZnO-Bi_2O_3$계는 CoO를 첨가하면 hole에 의한 emission특성을 나타내고, MnO를 첨가하면 전자에 의한 emission특성을 나타냄을 알 수 있었다. 그리고 비 직선저항계수 $\alpha$는 도너농도의 감소에 직접적으로 비례하였으나, 포획준위의 밀도와는 별다른 비례관계를 발견할 수 없었다. 결론적으로 $ZnO-Bi_2O_3-MnO$계에 CoO를 첨가함에 따라 $\alpha$값이 증가하는 한편, 포획준위밀도는 CoO의 첨가로 감소함을 알 수 있었다.

• 한국재료학회지
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• 제11권1호
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• pp.44-47
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• 2001

Ni 전극을 사용하는 $BaTiO_3$계 내환원성 X7R 조성에서 $Er_2$$O_3$ 첨가가 유전특성에 미치는 영향에 대하여 환원성 분위기에서 연구하였다. $MnO_2-MgO$가 첨가된 내환원조성에서 첨가량이 조절된 $Er_2O_3$의 복합첨가로 유전율의 온도안정성이 향상되어 X7R 규격을 만족시켰으며 2,970 이상의 상온 유전상수와 1.0% 이하의 유전손실율이 관찰되었다. $Er_2O_3$가 3.0 mol% 이상으로 과량 첨가되었을 경우 유전체의 온도특성은 향상되었으나 상온 유전상수가 현저히 감소하였다. 다른 첨가조성(1.5 mol% $Er_2O_3$2.0 mol% MgO)이 고정될 때 TCC곡선은 $MnO_2$첨가량이 증가함에 따라 시계방향으로 회전하였으며, 온도안정성을 향상시켰다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1537-1539
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• 1997

In this study, the dielectric properties of $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$ Ceramics have been investigated as a addition of the amount of $MnO_2(0{\leq}x{\leq}0.9wt%)$. The Temperature-dependant dielectric characteristics of 0.9PMN-0.1PT relaxor ferroelectric system were improved by enhencing the extent of the diffuse phase transition(DPT). The maximum dielectric permittivity decreased by substitution $MnO_2$ and the dielectric loss decreased with increasing $MnO_2$ substitution amount. It is expected decreasing in inner heat energy for temperature with increasing $MnO_2$ substitution.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 춘계학술대회 논문집
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• pp.133-137
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• 1994

Infrared radiator of Cordierite system were manufactured using Cordierite(2Mgo$.$2Al$_2$O$_3$$.$5SiO$_2$) and Clay 30wt% as main materials and addition of MnO$_2$ from 0. 1 to 2 5wt% of Dry pressing and slip casting The effects of MnO$_2$ additives on the thermal properties of infrared radiator of Cordierite system. The more the thermal expansion could be lowered the more the amount (wt%) of additives MnO$_2$is increased in the below 4.5$\mu\textrm{m}$. The high efficiency Infrared radiator of Cordierite system using dry pressing method when the amount of additives MnO$_2$is 2.0 wt%

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.474-477
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• 2001

The properties of LiMnO$_2$ was studied as a cathode active material for lithium polymer batteries. LiMnO$_2$ cathode active materials were synthesized by the reaction of LiOH . $H_2O$ and Mn$_2$O$_3$at various temperature under argon atmosphere. For lithium polymer battery applications, the LiMnO$_2$cell was characterized electrochemically by charge-discharge experiments and a.c. impedance spectroscopy. And the relationship between the characteristics of powders and electrochemical properties was studied in this research. A maximum discharge capacity of 160-170 mAh/g for ο-LiMnO$_2$ cell was achieved. Used that SP270 as electric active material in LiMnO$_2$, it is excellent than property of electric active material used Acetylene black or KS6 at charge/discharge capacity.

• 한국세라믹학회지
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• 제19권4호
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• pp.293-299
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• 1982

The effects of $MnO_2$ and $Cr_2O_3$ on the Piezoelectrictric properties of Pb(Mg1/2W1/2)0.3 Ti0.4 Zr0.3O3 Ceramics. Electromechanical properties in the system in connection with the sintering temperature and the effects of $MnO_2$ and $Cr_2O_3$ addition. The dielectric constant of the ceramics decreased with the additions of $MnO_2$ while the additions of $Cr_2O_3$ increased the value. The Planar coupling factor (Kp) of the ceramics with 0.2wt% $MnO_2$ and with 0.2wt% $Cr_2O_3$ gave the highest value of 0.52 and 0.513 as sintered at 106$0^{\circ}C$, 108$0^{\circ}C$, respectively. The value of mechanical Q-factor were in parallel with the fired density of the ceramics. The optical micrography of the sintered bodies showed that the additions of $MnO_2$ promoted the grain growth, while the additions of $Cr_2O_3$ retarded the grain growth.

• 한국전기전자재료학회논문지
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• 제29권9호
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• pp.539-545
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• 2016

Alumina added with Mn3O4 up to 7.5 cat% of Mn was prepared by conventional ceramic processing, and the sintering behavior and the optical properties of which were studied as functions of Mn content. Densification and grain growth of alumina were enhanced by Mn addition up to 0.75 cat% but was leveled off at higher concentrations. XRD revealed that $Al_2MnO_4$(galaxite) was formed as a second phase in the specimens with more than 0.75 cat% of Mn. Thus it is believed that either the solid solution effect of Mn or the Zener effect of $Al_2MnO_4$ becomes predominant in the sintering of Mn-added $Al_2O_3$ according to the additive concentration. UV-VIS reflectivity(SCI) spectra of Mn-added $Al_2O_3$ consisted of smooth bottoms in 300~550 nm wavelength range and plateaus at wavelengths longer than 650 nm. The reflectivity spectrum continuously moved downward, and the specimen color became darker and thicker with increasing Mn content. The CIELAB color change with respect to standard white was also dependent on the amount of Mn added: ${\Delta}L^*$(D65) negatively increased and ${\Delta}E_{ab}^*$(D65) positively increased with increasing Mn content, probably due to Mn substitution to Al and/or the mixing effect of black $Al_2MnO_4$ as a second phase.