• Electrical & Electronic Materials
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• v.9 no.6
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• pp.542-550
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• 1996

ZnO-based ceramic varistors containing NiO range 0.5 mol% to 4.0 mol% were fabricated by standard ceramic techniques. The influence of NiO on the microstructure and electrical behavior of ZnO varistor was investigated. As the content of NiO additive increases, average grain size decreased from 16.5.mu.m to 13.2.mu.m, and the amount of NiO existing in the grain interior and grain boundary region was approximately equal. NiO acted as an acceptor which decreases donor concentration due to the increase of Zn vacancy in the grain, and as a driver which migrates Zn interstitial in the depletion region toward the interface of grain boundary, which resulted in the decrease of interface state density. As a result, increasing the content of NiO additive, barrier height, nonlinear exponent, and varistor voltage decreased, and leakage current increased. Wholly, the physical and electrical properties of the ZnO varistor can be said to be affected by the NiO additive.

• Journal of the Korean Magnetics Society
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• v.16 no.4
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• pp.201-205
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• 2006

The electromagnetic properties and microstructure of the basic composition of $(Ni_{0.2}Cu_{0.2}ZnO_{0.2})_{1.02}(Fe_{2}O_{3})_{0.98}$ were invested, changing the amount of the additives $Bi_2O_3$ and $ZrO_2$ and sintering temperature. The spinel structure of specimen was confirmed by the analysis of XRD patterns. Grain size and its density are increased by increasing the additive and the sintering temperature.However, the permeability increased with decreasing additive. It was also found that $Bi_2O_3$ had more effect on the increase of grain size and permeability rather than $ZrO_2$.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1119-1123
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• 2002

Nanostructured spinel NiZn ferrites were prepared by the sol-gel method from metal nitrate raw materials. Analyses by X-ray diffraction and scanning electron microscopy showed the average particle size of NiZn ferrite was under 50 nm. The single phase of NiZn ferrites was obtained by firing at 250${\circ}C$, resulting in nanoparticles exhibiting normal ferrimagnetic behavior. The nanostructured $Ni_{1-X}Zn_XFe_2O_4$ (x=0.0∼1.0) were found to have the cubic spinel structure of which the lattice constants ${\alpha}_2$ increases linearly from 8.339 to 8.427 ${\AA}$ with increasing Zn content x, following Vegard's law, approximately. The saturation magnetization $M_s$ was 48 emu/g for x=0.4 and decreased to 8.0 emu/g for higher Zn contents suggesting the typical ferrimagnetism in mixed spinel ferrites. Pure NiZn ferrite phase substituted by Cu was observed before using the additive but hematite phase was partially appeared at $Ni_{0.2}Zn_{0.2}Cu_{0.6}Fe_2O_4$. On the other hand, the hematite phase in this NiZn Cu ferrite was disappeared after using the additive of acethyl aceton with small amount. The saturation magnetization Ms of $Ni_{0.2}Zn_{0.8-y}Cu_yFe_2O_4$(y=0.2∼0.6) as measured was about 51 emu/g at 77K and 19 emu/g at room temperature, respectively.

• Journal of the Korean Magnetics Society
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• v.8 no.2
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• pp.62-66
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• 1998

We have studied on the magnetic properties of the specimen with additives Bi$_2$O$_3$and$V_2O_5$ that sintered at 900 $^{\circ}C$ for 4 hours for sybthesizing optimal Ni-Zn-Cu ferrite. Curie temperature rises from 240 $^{\circ}C$ to 270 $^{\circ}C$ as Ni contents increase. Magentic maximum induction$(B_m)$ increases from 2650 G to 3300 G, 3500 G in the specimens with $V_2O_5$ and Bi$_2$O$_3$resectively. On the contrary coercive force $(H_c)$ lowers to 2.05 Oe~1.05 Oe. Permeability all increase in the specimen with additives. In the specimen with additive Bi$_2$O$_3$, we have obtained the low relative loss factor of $6.3{\times}10^{-5}~7.84{\times}10^{-5}$ in the range of 1MHz due to increase of resistivity in grain boundary. In the specimen with additive $V_2O_5$ in spite of increase permeability relative loss factor increase of due to decrease of Q-value.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1789-1791
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• 1999

In consideration of piezoelectric characteristic and Temperature stability, 3-element system dopped with NiO, $Cr_2O_3$ well-known as Hardner and Stabilizer whose primary element is PZT was eximanated its structure, piezoelectric characteristics, dopping with Nio, $Cr_2O_3$. We think that piezoelectric Characteristic is developed, remenent polarization and $E_c$ can developed in specimens by dopping with NiO, $Cr_2O_3$ additive. also, electromechanical quality factor largely showed tendency of decrement. According to dopping NiO, $Cr_2O_3$ more.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.323-323
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• 2010

PNN-PZT계 세라믹스를 $Pb(Ni_{1/3}Nb_{2/3})_{0.4}(Zr_{0.48}Ti_{0.52})_{0.6}O_3$ 조성으로 설계하고, 이에 낮은 융점의 NiO를 1wt% 첨가하여 저온소결 특성을 평가하였다. 일반적인 세라믹 분말 소결법을 이용하여 시편을 제작하였으며, 이때의 소결온도는 $850{\sim}105^{\circ}C$ 범위에서 변화시켰다. 소결체의 압전 및 유전적 특성을 평가를 하고. SEM 및 XRD를 이용한 미세구조 및 상 분석도 수행하였다. 이러한 실험 결과, PNN-PZT 세라믹은 NiO의 첨가로 $1000^{\circ}C$ 정도에서도 저온소결이 가능한 것을 확인하였다.

• Journal of the Korean Magnetics Society
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• v.13 no.3
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• pp.121-126
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• 2003

The electromagnetic properties and microstructures of the basic composition of (N $i_{0.2}$C $u_{0.2}$Z $n_{0.6}$)$_{1.085}$(F $e_2$ $O_3$)$_{0.915}$ were invested by changing of the additive Sn $O_2$, CaO amounts and ferrite processes. There is no variation of grain size by changing additive amount. It can reduce the total loss when (N $i_{0.2}$C $u_{0.2}$Z $n_{0.6}$)$_{1.085}$(F $e_2$ $O_3$)$_{0.915}$ composition sintered at 1150 $^{\circ}C$ better than 130$0^{\circ}C$. Additive CaO confirmed of useful addition for the reduce total loss, because it increasing sintering density. Decreasing total loss were observed by adding both Sn $O_2$ 0.06 wt％ and CaO 0.4 wt％.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.59-62
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• 1996

The effect of NiO addition on the microstructure and microwave dielectric properties of (Zr$_{0.8}$Sn$_{0.2}$)TiO$_4$(ZST) was investigated. With the NiO addition, a dense ZST body of density higher than 95% has been achieved in the sintering temperature range of 1400 to 150$0^{\circ}C$. Energy dispersive X-ray spectrometry (EDS) analysis of sintered specimen shows the presence of second phase at grain boundaries, which is considered to be NiTiO$_3$. Dielectric constant of the specimen is found to increase linearly with density. Q-values and TC$_{f}$decrease with increasing NiO content. The variation of dielectric properties with NiO content is discussed in term of the second phase. The ZST ceramics with small amount of additive gave $\varepsilon$$_{r}$=38, Q=7000 at 7 GHz and TC$_{f}$=-0.5 ppm/$^{\circ}C$, comparable with the values obtained by previous investigation.stigation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.347-350
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• 1995

In this paper, we fabricated fuel shortage detecting sensor, utilizing NTC thermistor concerned with Mn-Ni-Co system. We would be obtained B constant value of 1930∼2080 and resistivity 387∼430(ohm-cm) additive Bi$_2$O$_3$0∼0.5 wt% to Mn$_3$O$_4$:9wt%, Co$_3$O$_4$:61wt%, NiO:28wt% under 1150∼1250$^{\circ}C$ of sintering temperature. In sensor, we obtained characteristics, which we want, in resistance range 850∼l150$\Omega$, B constant 2000${\pm}$5%. we can see 15 multiplied differences between gasoline and heat dissipation coefficient of air condition.

• Journal of the Korean Ceramic Society
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• v.49 no.5
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• pp.423-426
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• 2012

$Al_2O_3$/NiO powder was obtained through hydrolysis-condensation reactions and thermal treatments. An organic additive, triblock copolymer surfactant P123, was added to the starting materials to control the surface area and morphology. The synthesized powder was characterized by X-ray diffractometry (XRD), field-emission scanning electron microscopy (FE-SEM) and a Brunner-Emmett-Teller surface analysis (BET). The heterogeneous catalytic activity of this powder was applied to an epoxidation reaction of styrene and was monitored using a gas chromatograph with mass spectrophotometry (GC/MS).