• 한국세라믹학회지
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• 제36권10호
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• pp.1108-1114
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• 1999

Microstructure and electrical properties of ZnO-doped (0-5 mol%) 0.05 Pb(Mn1/3Sb2/3)O3-0.95 PZT ceramics were investigated. Sintering temperature was decreased to 100$0^{\circ}C$ due to eutetic reaction between PbO and ZnO. Grain-size increased up to adding 1mol% ZnO and then decreased. Compositions of grain and grain-boundary were investigated by WDS. Lattice parameter was decreased with ZnO addition. Density increased with ZnO addition and reached to the maximum of 7.84(g/cm2) at 2 mol% ZnO. The effect of ZnO on electrical properties of PMS-PZT was investigated. At 3mol% ZnO addition electromechanical coupling factor(kp) was about 50% and relative dielectric constant($\varepsilon$33/$\varepsilon$0) was 997 Mechanical quality factor(Qm) decreased with ZnO addition. Lattice parameters and tetragonality(c/a) were measured to investigate relationship between the electric properties and substitution of Zn2+. At 3 mol% ZnO tetragonality was maximiged at c/a=1.0035 Curie temperature (Tc) decreased slightly with ZnO addition.

• 한국세라믹학회지
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• 제32권1호
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• pp.106-112
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• 1995

In order to examine the effect of CuO and Al2O3 addition on the electrical conductivity of ZnO, both Al2O3 (0, 1, 2, 5, 10at.%) and CuO (1, 5at.%) were added to ZnO. Al2O3 addition (~2at.% Al) increased the total electrical conductivity of ZnO which was already decreased by CuO doping effect Above solid solubility of Al (~2at.%), ZnAl2O4 formed and the total electrical conductivity decreased due to the decrease of sintered density. Impedance measurements were used to know the reason and degree of contribution of three resistive elements, ZnO grain, ZnO/CuO, and ZnO/ZnO grain boundaries, to the total electrical conductivity changed.

• 전기학회논문지
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• 제59권11호
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• pp.2021-2025
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• 2010

Electrical and structural properties were investigated on the effects of ZnO and the lead-free NKN-LST ceramics with the addition of ZnO were fabricated by a conventional mixed oxide method. A gradual change in the crystal and microstructure was observed with the increase of ZnO addition. For the NKN-LST-ZnO ceramics sintered at $1050^{\circ}C$, bulk density increased with the addition of ZnO and showed maximum value at addition 2.0mol% of ZnO. Curie temperature of the NKN-LST-ZnO ceramics slightly decreased with adding ZnO. The dielectric constant, piezoelectric constant ($d_{33}$) and electromechanical coupling factor ($k_p$) increased at the small amount of ZnO addition, which might be due to the increase in density. The high piezoelectric properties = 153 pC/N, electromechanical coupling factor = 0.484 and dielectric constant = 2883 were obtained for the NKN-LST+0.5ZnO ceramics sintered at $1050^{\circ}C$ for 2h.

• 한국전기전자재료학회논문지
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• 제13권10호
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• pp.834-839
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• 2000

The structural properties that SEM photograph of ZnO varistors surface studied by fractal mathematics program were investigated to verify the relations of electrical characteristics. The SEM photograph of ZnO varistors surface were changed by binary code and the grain shape of that were analyzed by fractal dimension. The void of ZnO varistors surface was found by fractal program. The relation between grain density and electrical properties depend on fractal dimension. The grain size in ZnO varistors surface was decreased by increasing of Sb$_2$O$_3$ addition. The spinel structure was formed by Sb$_2$O$_3$addition and it was depressed the ZnO grain formation. The grain size of ZnO by Sb$_2$O$_3$addition were from 5 to 10[${\mu}{\textrm}{m}$]. Among of ZnO varistors, fractal dimension of ZnO4 was very high as a 1.764. The density of grain boundary in ZnO2 and ZnO3 varistors surface was 15[%] by formed spinal structure. The breakdown electric field of ZnO2 that fractal dimension has 1.752 was very high to be 8.5[kV/cm]. When the fractal dimensin was high, the grain shape of ZnO varistors was complex and the serial layers of ZnO grain was increased.

• 한국세라믹학회지
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• 제31권11호
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• pp.1396-1400
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• 1994

Electrical properties in the ZnO-Bi2O3-CoO-Zn7Sb2O12 system were investigated with Zn7Sb2O12 content (0.1~2 mol%). The increase of the Zn7Sb2O12 content inhibited the grain growth of ZnO, which showed a narrow grain size distribution of ZnO. The breakdown voltage (Vb) increased markedly with 1 mol% Zn7Sb2O12 addition due to the grain growth control behaviour of the Zn7Sb2O12 . The nonlinear I-V characteristic was significantly influenced by the Zn7Sb2O12 content (or Bi2O3/Zn7Sb2O12 ratio). Addition of 0.5 mol% Zn7Sb2O12 showed the highest nonlinear coefficient ($\alpha$) of 43. The leakage current in prebreakdown region was decreased with increasing Zn7Sb2O12 content.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권7호
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• pp.347-351
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• 2004

The $ZnNb_2O_{6}$ ceramics with CuO(1, 3, 5wt%) were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of $950^{\circ}C$∼$1075^{\circ}C$ for 3hr in air The structural properties and the microwave dielectric properties of $ZnNb_2O_{6}$ ceramics were investigated with sintering temperature and the addition of CuO. Increasing the addition of CuO, the peak of second phase($Cu_3Nb_2O_{8}$) was increased. The grain size of the $ZnNb_2O_{6}$ ceramics with CuO was increased with CuO addition at same temperature. The dielectric constant of $ZnNb_2O_{6}$ ceramics with CuO was increased with sintering temperature and CuO addition. While the quality factor of the $ZnNb_2O_{6}$ ceramics with lwt% CuO depended on sinterability, the quality factor of $ZnNb_2O_{6}$ with 3wt% and 5wt% CuO depended on second Phase due to the CuO addition. The optimum dielectric Properties of $\varepsilon$$_{r}$ = 21.73 Q${\times}$f = 19,276 were obtained from the condition of 3wt% CuO addition and sintering temperature of $1025^{\circ}C$(3hr).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.193-195
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• 2005

[ $0.96[Bi_{0.5}(Na_{0.84}K_{0.16})_{0.5}TiO_3]+0.04SrTiO_3+0.3wt%Nb_2O_5+0.2wt%La_2O_3+xwt%ZnO$ ], were studied in order to develope the superior piezoelectric properties of Lead-free piezoelectric ceramics. With increasing amount of ZnO addition, density showed the maximum value of 5.79(g/$cm^3$) at 0wt% ZnO addition, and electromechanical coupling factor($k_p$) and dielectric constant decreased, and mechanical quality factor($Q_m$) increased and showed the maximum value of 280 at 0.4wt% ZnO addition.

• 한국결정성장학회지
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• 제24권2호
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• pp.70-76
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• 2014

아연결정유약에 Anatase 형 $TiO_2$에 의해 생성되는 $Zn_2TiO_4$가 효과적인 결정 생성제로 나타났다. 이에 저온에서 생성되는 $Zn_2TiO_4$를 인위적으로 합성하여 유약의 미치는 효과를 규명하였다. 첨가 $Zn_2TiO_4$는 저온에서 생성되는 결정으로 아연결정 W의 핵으로 작용하는 것으로 밝혀졌다. 합성된 $Zn_2TiO_4$를 유약에 5 wt% 첨가하면 유약 내에 결정생성이 증가하며 안정적으로 유지된다. 특히, $Zn_2TiO_4$ 합성 시 발색제로 CoO, NiO, CuO를 각각 고용시켜 유약에 첨가하면 발색제의 고용효과가 커져 Willemite 결정의 다양한 발색에 큰 효과를 얻을 수 있다.

• 한국세라믹학회지
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• 제28권6호
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• pp.471-477
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• 1991

Effects of ZnO, PbO and SiO2 on the grain growth and magnetic properties of Sr-ferrite were investigated. (1) Addition of ZnO to Sr-ferrite increased remanence, but decreased coercivity and maximum energy product. (2) Addition of PbO up to 0.5 wt% increased (B$.$H)max of Sr-ferrite, but addition more than 0.5 wt% decreased (B$.$H)mzx (3) SiO2 addition to the 0.5 wt% PbO doped Sr-ferrite decreased remanence and increased coercivity. The coercivity increase in due to the grain refinement effect of SiO2. But addition of SiO2 more than 0.5 wt% invoked a decrease of coercivity and (B$.$H)max of Sr-ferrite due to abnormal grain growth. Sr-ferrite magnet having maximum energy product of 3.7MGOe was fabricated by using the roasting product of Pyrrhotite.

• 한국세라믹학회지
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• 제29권2호
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• pp.101-106
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• 1992

Sintering behavior, distribution of dopant oxides and electrical properties in the ZnO-Bi2O3-CoO-Sb2O3 and ZnO-Bi2O3-CoO-Sb2O3-Cr2O3 systems were studied. The linear shrinkage of ZnO varistors from 850 to 950$^{\circ}C$ was related to the decomposition reaction (py\longrightarrowsp+Bi2O3) of the pyrochlore phase. In the distribution of the dopant oxides (CoO, Sb2O3, Cr2O3), Co distribute uniformly throughout the sample, the distribution of Sb coincided with small particles (spinel phase, Zn7Sb2O12), and Cr distributed very consistently with Sb. The increase in breakdown voltage, due to the addition of Cr2O3, was not only attributed to the decrease in the ZnO grain size but also to the solution of Cr2O3 in the spinel phase. The leakage current (80% V60 ${\mu}\textrm{A}$) was increased by the addition of Cr2O3.