• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.747-749
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• 1992

In this study, $0.45Pb(Fe_{1/2}Nb_{1/2})O_3-(0.55-x)Pb(Fe_{2/3}W_{1/3})O_3-xPb(Mg_{1/3}Nb_{2/3})O_3(x=0.20, 0.25, 0.30)$ (x=0.20, 0.25, 0.30) ceramics were fabricated by the mixed oxide method. The sintering temperature and time were 950-990[$^{\circ}C$], 2[hr], respectively. The dielectric and structural properties with the composition and sintering temperature were investigated for the application as multilayer ceramic capacitors. To improve the dielectric loss, specimens doped with $MnO_2$, (0$\sim$2.0 [mol%] ) were fabricated and their dielectric properties were studied. With increasing the amount of $MnO_2$, dielectric constant was decreased and transition temperature was increased. Dielectric constant and dielectric loss of the 0.45PFN-0.30PFW-0.25PMN+$MnO_2$(1.0[mol.%]specimen(970[$^{\circ}C$]) had a good properties of 11,227, 1.3[%].

• Transactions on Electrical and Electronic Materials
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• v.5 no.3
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• pp.109-112
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• 2004

In this study, in order to develop the low temperature sintering ceramics for ultrasonic vibrator, Pb(Sb$\_$$\frac{1}{2}$/Nb$\_$$\frac{1}{2}$/) O$_3$-Pb(Ni$\_$1/3/Nb$\_$2/3/)O$_3$-Pb(Zr$\_$0.48/Ti$\_$0.52/)O$_3$ ceramics were manufactured as a function of the amount of CuO addition, and their dielectric and piezoelectric characteristics were investigated. With increasing CuO addition, the grain size and density increased up to 0.3 wt% CuO addition. Taking into consideration electromechanical coupling factor(k$\_$p/) of 0.53, mechanical quality factor(Q$\_$m/) of 423, dielectric constant($\varepsilon$$\_$r/) of 1,759 and piezoelectric constant(d$\_$33/) of 362pC/N, it could be concluded that 0.5 wt% CuO added composition ceramic sintered at 920$^{\circ}C$ was suitable for ultrasonic vibrator application.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.686-689
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• 2002

The application of the ultrasonic nozzle has been extended because it is possible atomization of liquid material. In this study, the characteristics of the ultrasonic nozzle and ceramic oscillator were investigated. The oscillator for the ultrasonic nozzle were made piezoelectric ceramic of $Pb[(Sb_{1/2}Nb_{1/2})_{0.035}-(Mn_{1/3}Nb_{2/3})_{0.065}-(Zr_{0.49}Ti_{0.51})_{0.90}]O_3$. The electromechanical coupling factor$(k_p)$ and mechanical quality factor$(Q_m)$ showed the values of 0.555, 1,214 respectively when the Zr/Ti ratio was 49/51. Moreover, this oscillator will have the temperature stability because it's curie temperature is $322[^{\circ}C]$. The driving current of ultrasonic nozzle showed the value of 80[mA] when the driving time was 10[min.]. Also, The surface temperature of ceramic oscillator showed $80[^{\circ}C]$ at driving time 10[min.] We knew that the ultrasonic nozzle had stabile driving above 10[min.].

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.1
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• pp.27-32
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• 2001

The 0.9PMN-0.1PT powders was prepared by the sol-gel process, and the effect amounts of ${Mg(OC_{2}H_{5})}_2$ and ${Pb(CH_{3}COO)}_2.3H_{2}O$ as starting materials was studied. As a result the percent of perovskite phase of the calcined powders increased with increased calcination temperatures. Maximum of perovskite phase was at $850^{\circ}C$ for 4 hrs. 0.9PMN-0.1PT powder by addition of 5 wt% excess ${Mg(OC_{2}H_{5})}_2$ crystallized to perovskite phase with a ${\fallingdotseq}100%$ yield.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.417-420
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• 2006

The composition and structure of dendrite phase within $Zr_{76.11}Ti_{4.20}Cu_{4.51}Ni_{3.16}Be_{1.49}Nb_{10.53}$ bulk metallic glass (BMG) were confirmed by using an EPMA, XRD and TEM, respectively. The chief elements of dendrite phase were Zr-Ti-Nb and had a BCC structure. The thermal properties of this BMG have been then subsequently investigated by using a differential scanning calorimeter (DSC). The glass transition and crystallization onset temperatures were determined as $339.7^{\circ}C$ and $375.8^{\circ}C$ for this alloy, respectively. Mechanical properties have also been examined by conducting a series of uniaxial compression tests at various temperatures within supercooled liquid region under the strain rates between $10^{-4}/s$ and $3{\times}10^{-2}/s$. The deformation behavior of BMG composite within supercooled liquid region is similar to one of Vit-1 exhibiting amorphous single phase alloy. The flow stresses of BMG composite, however, are entirely higher than those of Vit-1 because dendrite phases are interfere with moving of atoms.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.218-218
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• 2008

최근 미관을 위하여 소형 네온관 등이 사용되고 있다. 따라서 네온관 등 구동에 사용되는 인버터는 안정기 역할을 하면서 소형화와 경량화가 중요한 요소이다. 본 연구는 압전 특성이 우수한 PZT계 세라믹스 조성인 $(Pb_{0.94}Sr_{0.06})[(Ni_{1/2}W_{1/2})_{0.02}(Mn_{1/3}Nb_{2/3})_{0.07}(Zr_{0.51}Ti_{0.49})_{0.91}]O_3$에 특성 향상을 위해 PbO, $Fe_2O_3$, $CeO_2$, Xwt% $Nb_2O_5$ 조성별로 첨가하였으며 그에 따른 유전, 압전 특성을 조사하고 또한 Rosen type의 압전 트랜스포머를 제작하여 각 조성별 변환효율을 측정하였다. 실험방법은 일반적인 세라믹스 제조공정으로 파우더 혼합 후 24시간 ball milling하고 $850^{\circ}C$ 에서 2시간 하소 후 $1230^{\circ}C$에서 2시간 소결하였다. 또한 최종 소결 시편을 이용하여 Rosen type의 압전 트랜스포머를 제작하였다. 상 분석을 위해 XRD를 이용하여 perovskite구조를 확인하고 미세구조확인을 위해 SEM으로 관찰하였다. 압전 특성을 평가하기 위해 압전 $d_{33}$ Meter를 사용하였으며, Impedence analyzer HP 4194A를 이용하여 전기적 특성을 측정하였다.

• Transactions on Electrical and Electronic Materials
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• v.18 no.6
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• pp.334-337
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• 2017

In this paper, to develop the ceramics with high $d_{33}$ and high $Q_m$ for ultrasonic transducer applications, $0.10Pb(Ni_{1/3}Nb_{2/3})O_3-0.07Pb(Mn_{1/3}Nb_{2/3})O_3-0.83Pb(Zr_{0.5}Ti_{0.5})_{0.83}O_3$ (PNN-PMN-PZT) ceramics were sintered at $940^{\circ}C$ using $CuO-Li_2CO_3-Bi_2O_3$ (CLBO) as a sintering aid by a traditional solid-state technique. The influence of zinc oxide additive on the physical properties of the prepared ceramics were systematically investigated. The R-T (rhombohedral-tetragonal) phase coexistence was found in the ceramics without zinc oxide additive and with increasing amounts of ZnO additive, the specimens showed a tetragonal phase. The formation of a liquid phase between ZnO and $Bi_2O_3$ contributed significantly to the grain growth of specimens. For the 0.1 wt% ZnO ceramics, the optimal physical properties of $d_{33}=370pC/N$, ${\varepsilon}_r=1,344$, $k_p=0.621$, and $Q_m=1,523$ were obtained.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.9
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• pp.611-615
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• 1999

Piezoelectric properties of PMN-PZT ceramics with $CeO_2$ impurity were investigated. Mechanical quality factor, $Q_m$ of 1792, 1285 and the electromechanical coupling coefficient, $k_p$ of 0.52, 0.54 were obtained from the specimen with 0.25 and 0.5 mole % $CeO_2$ respectively. Curie temperature was decreased with the addition of $CeO_2$ while the electric coercive field was proportional to the amount of impurity. Based on the system ceramics with 0.5 mole % cerium oxide, a Rosen type piezoelectric transformer was fabricated and tested. Voltage step-up ratios of 230 and 13 were obtained from the transformer at no load and $100 k\Omega$ resistance, respectively. Experimental results showed a potential of the transformer for the practical use coupled with the expected strength increase by the grain size refinement.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.494-496
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• 2000

The properties of piezoelectric and dielectric for 0.05Pb$(Mn_{0.4}W_{0.2}Nb_{0.4})O_3$ - $0.95PbZr_{x}Ti_{1-x}O_{3}$ compositions have been investigated. In the composition of 0.05Pb$(Mn_{0.4}W_{0.2}Nb_{0.4})O_3$-$0.95PbZr_{0.51}Ti_{0.49}O_{3}$, the values of $k_p$ and ${\varepsilon_{33}}^T/{\varepsilon}_0$ are maximized, but $Q_m$ was minimized ($k_p$=56.5[%], $Q_m$=1130, $d_{33}$=258[pC/N], ${\varepsilon_{33}}^T/{\varepsilon}_0$=1170). The grain size was suppressed and the uniformity of gram was improved at the $1100[^{\circ}C]$. Dielectric constant increase at the Ti rich, but decrease at the Zr rich after poling. Because the dielectric constant after poling is determined by compromising effects between dipole switching and electostriction inducing stress(dielectric constant increasing factor) and dipole rotation to the poling direction (dielectric constant decreasing factor).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.1
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• pp.33-38
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• 2003

Highly homogeneous PZT powder was prepared by a partial oxalate method using chemicals of (Z $r_{0.53}$ $Ti_{0.47}$) $O_2$, Pb(N $o_3$)$_2$and (COOH)$_2$ㆍ2$H_2O$. N $b_2$ $O_{5}$ addition effect on microstructure and electrical properties of PZT ceramics was investigated. When the precursors were calcined at 71$0^{\circ}C$, a single perovskite phase was obtained. After sintering at 110$0^{\circ}C$, X-ray diffraction Patterns showed coexistence of rhombohedral and tetragonal phases regardless of the N $b_2$ $O_{5}$ content. As the content of N $b_2$ $O_{5}$ increased, grain size decreased but sintered density increased. The electromechanical coupling factor of kp and the piezoelectric constant of $d_{31}$ increased linearly with the content of N $b_2$ $O_{5}$, and those values reached 0.7 and -200, respectively, when 1.2 mol% of N $b_2$ $O_{5}$ is added. is added.ded.