• 한국세라믹학회지
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• 제27권6호
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• pp.713-720
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• 1990

The effects of substituting Zn+2 for Ni+2 ion on dielectric and piezoelectric prooperties of Pb(Zn1/3Nb2/3)O3-Pb(Ni1/3Nb2/3)O3-PZT ceramics were investigated. With increasing Zn2+ contents the tetragonality was appreciably enhanced and the grain size decreased. Both Curie temperature and thermal stability were increased with increase in Zn2+ contents since the Zn+2 partial substition for Ni+2 could form solid solution in almost range of the composition investigated. Piezoelectric prooperties showed the maximum($\varepsilon$ T/$\varepsilon$0=5014, kp=0.56, d31=250$\times$10-12m/V) in 4.5Pb(Zn1//3Nb2/3)O3-40.5Pb(Ni1/3Nb2/3)O3-55PZT composition sintered at 125$0^{\circ}C$ and then decreased again due to the phase boundary movement for tetragonal phase of the solid solution of Zn2+ amount.

• 한국전기전자재료학회논문지
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• 제24권7호
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• pp.559-562
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• 2011

In this study, the effect of $Nb_2O_5$ and sintering time on the positive temperature of coefficient of resistivity (PTCR) behavior of lead free $Ba_{0.99}(Bi_{0.5}Na_{0.5})_{0.01}TiO_3$ (BBNT) ceramics were investigated in order to fabricate a PTC thermistor with high $T_c$ temperature more than $140^{\circ}C$. In particular, BBNT ceramic doped with 0.1mol% $Nb_2O_5$ and sintered at $1350^{\circ}C$ for 4 h has significantly increased Curie temperature ($T_c$) of about $200^{\circ}C$, showed good PTCR behavior of room-temperature resistivity ($\rho_{rt}$) of $40{\Omega}{\cdot}cm$, a high $\rho_{max}/\rho_{min}$ ratio of $43.78{\times}10^3$ and a large resistivity temperature factor (${\alpha}$) of 16.1%/$^{\circ}C$. With increasing addition of $Nb_2O_5$ content, the $\rho_{rt}$ decreased to a minimum value of $40\;{\Omega}cm$ at 0.1mol% $Nb_2O_5$ and the $\rho_{rt}$ increased for x value over 0.1 mol%.

• 한국세라믹학회지
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• 제34권9호
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• pp.921-926
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• 1997

Two NbCx-C1-x/Y2O3/Ti sputter-coated Al2O3 substrates (L 5.5 cm$\times$W 0.5 cm) were diffusion bonded together using hot press method at 95$0^{\circ}C$ for 3 hours under 1 MPa of applied pressure. 4 points bending tests were used to evaluate the mechanical performance of these precracked laminate beams. Two types of mechanical responses were observed: crack penetration through the interface for x=0.75, 1 and crack deflection into an interface for x=0.25, 0.5. The Al2O3/NbCx-C1-x/Y2O3/Ti system suggested here has been proves to be effective for the thermokinetical stability and tailorability of the interfaces of Al2O3/Ti composites at 95$0^{\circ}C$.

• 한국세라믹학회지
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• 제30권9호
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• pp.723-730
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• 1993

The mechanism of formation of perovskite phase and the dielectric properties of PZMN[Pb(Zn, Mg)1/3Nb2/3O3] ceramics were examined using two different types of the columbite precursors, (Mg, Zn)Nb2O6 (MZN) and MgNb2O6＋ZnNb2O6 (MN＋ZN). The formatin of perovskite phase in PbO＋MN＋ZN system is characterized by an initial rapid formation of Mg-rich perovskite phase, followed by a sluggish formation of Zn-rich perovskite phase. On the other hand, thepyrochlore/perovskite transformation in the PbO＋MZN system proceeded uniformly with a spatial homogeneity. The degree of diffuseness of the rhombohedral/cubic phase transitionis higher in the PbO＋MN＋ZN system than in the PbO＋MZN specimen, indicating a broadened compositional distributjion of the B-site catons (Nb+5, Zn+2, Mg+2) in the PbO＋MN＋ZN system.

• 한국세라믹학회지
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• 제30권1호
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• pp.17-24
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• 1993

Sol-gel spin-coating technique was used to produce Nb2O5 thin films on silicon substrates from Nb(OC2H5)5 precursor. The films were heat-treated at temperatures between $600^{\circ}C$ and 100$0^{\circ}C$ in oxygen atmosphere and their crystalline phases, chemical states, and dielectric characteristics were investigated by X-ray diffractometry (XRD), Auger electron spectroscopy (AES), and C-V measurements, respectively. After 1 hour heat-treatment at 80$0^{\circ}C$, T-type Nb2O5 was formed, and its chemical composition was homogeneous with no appreciable SiO2 oxide at interfaces between the films and substrates. The films heat-treated at temperatures between $600^{\circ}C$ and 80$0^{\circ}C$ exhibit dielectric constant of less than 20 while the films heat treated at 100$0^{\circ}C$ show dielectric constant of 28.

• Transactions on Electrical and Electronic Materials
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• 제12권2호
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• pp.72-75
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• 2011

In this study, $(K_{0.5}Na_{0.5})(Nb_{0.97}Sb_{0.03})O_3+0.9$ mol% $K_{5.4}Cu_{1.3}Ta_{10}O_{29}+x$ mol% $K_4CuNb_8O_{23}$ (x = 0, 0.2, 0.6, 0.8) ceramics were prepared by a conventional mixed oxide method. Their microstructure and electric properties were investigated. The secondary phase was made by virtue of $K_4CuNb_8O_{23}$ (KCN) addition in the $(K_{0.5}Na_{0.5})(Nb_{0.97}Sb_{0.03})O_3$ system ceramics. However, the sinterability of the ceramics increased with increasing $K_4CuNb_8O_{23}$ content. At the 0.6 mol% $K_4CuNb_8O_{23}$ added composition ceramics sintered at $1,060^{\circ}C$, kp and $d_{33}$ showed the optimum values of 0.39 and 145 pC/N, respectively, suitable for piezoelectric actuator application.

• 한국결정성장학회지
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• 제5권2호
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• pp.152-164
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• 1995

NaCl과 KCl을 1 : 1 mole비로 한 용융염 합성법으로 $xPb(Fe_{1/2}Nb_{1/2})O_3 - (1 - x)Pb(Mg_{1/3}Nb_{2/3})O_3$(x=0-1.0)을 제조하였으며, 이의 분말 특성 및 유전성을 연구하였다. 용융염 합성법에 의해 제조된 $xPb(Fe_{1/2}Nb_{1/2})O_3 - (1 - x)Pb(Mg_{1/3}Nb_{2/3})O_3$의 분말은 $2 \mu\textrm{m}$ 이하의 평균입도를 갖고 비교적 응집이 적었다. 용융법 합성법으로 제조된 $x0.3Pb(Fe_{1/2}Nb_{1/2})O_3-0.7Pb(Mg_{1/3}Nb_{2/3})O_3$ 세라믹스는 $1000{\times}C$에서 제조가 가능하며, 11,000이상의 유전상수를 갖는다.

• 한국세라믹학회지
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• 제32권6호
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• pp.748-760
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• 1995

Pyroelectric properties, figure of merits, and the other properties of the Pb(Zn1/3Nb2/3)O3-Pb(Fe1/2Nb1/2)O3 system, as expected to have excellent pyroelectric properties in the operating temperature range of pyroelectric type infrared sensor, were investigated. In the Pb(Zn1/3Nb2/3)O3-Pb(Fe1/2Nb1/2)O3 system, suppression of the pyrochlore phase depended on sintering condition, as like sintering temperature, holding time, sintering atmosphere. The specimen, sintered by the same composition atmosphere powder at 105$0^{\circ}C$ for 1.5h, possessed the best physical property. It was found that the piezoelectric parameters were mainly depended on the amount of spontaneous polarization and then the 0.2PZN-0.8PFN showed the best pyro- and piezoelectric properties. In terms of the experimental method, two pyroelectric-testing methods, i.e. static and dynamic methods, had a same tendency. Also the result of pyroelectric testing by the static method indicated that the diffuse phase transitiion resulted in the temperature difference of phase transition between dielectric constant and pyroelectric coefficient.

• 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.

• 한국세라믹학회지
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• 제35권3호
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• pp.294-302
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• 1998

$Pb_{1+x}$($Fe_{0.5}$$Nb_{0.5}$)$O_3$ films have been synthesized on Pt/Ti/$SiO_2$/Si substrates using rfmagnetron sputtering Concentration of Fe and Nb in the deposited films was adjusted to near stoichiometry through the control of target composition, Films deposited with adjusted to near stoichiometry showed better electrical properties such as dielectic and leakage characteristics. Crystallinity and dielectric constant increased with increasing excess PbO upto 9 mol% This study also showed that dielectric constant and leakage current characteristics improved by optimum content of $O_2$ flow during deposition.