• 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).

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1330-1332
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• 1997

In this paper, PNN-PZN-PZT ceramics were fabricated with various mole ratio of the PZT[$Pb(Zr_{1/2}Tid_{1/2})O_3$]. PNN [$Pb(Ni_{1/3}Nb_{2/3})O_3$] and PZN[$Pb(Ni_{1/3}Nb_{2/3})O_3$ powders prepared by double calcination and PZT powders prepared by molten-salt synthesis method. The formation rate of perovskite phase in PNN-PZN-PZT ceramics could be obtained about 92% at PZT 0.3 mole ratio. The relative permittivity of specimen with PZT 0.3 mole ratio was shown 5,320 and appeared the relaxor ferroelectric feature. The maximum piezoelectric coefficient $d_{31}$ to be used for evaluation the displacement of piezoceramics in PNN-PZN-PZT ceramics was $324{\times}10^{-12}$(C/V) at the vicinity of morphotropic phase boundary and was larger than that of solid PZT ceramics($120{\times}10^{-12}C/V$).

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1416-1418
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• 1994

Expressions for the displacement of a bimorph, one end fixed and the other free, has been introduced when sinusoidal inputs were applied to the ceramic plates on a thin metal plate. Maximum displacements at the free end and strains at the position of strain gage attached were measured when various wave forms, voltages, and frequencies were applied to the bimorph whose length is 6.6[cm], width 2.5[cm], and thickness 0.0365[cm]. Under the constant voltage ( $70[V_{peak}]$ ), the strains and the displacements at the free end were larger than the case of the sinusoidal input when the square wave was applied and were smaller when triangular wave. It was shown that the displacements at the free end and the strains of the gage position were increased as the applied voltage in the range of $30-90[V_{peak}]$ and effective length were increased. And it was also found that the resonant frequency of a bimorph was decreased as its effective length was increased, and that the displacements and the strains were maximum at the resonant frequency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.11
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• pp.790-800
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• 2013

The optimal structure of 1-3 piezocomposites has been determined by controlling polymer properties, ceramic volume fraction, thickness of composite and aspect ratio of the composite to maximize the TVR (transmitting voltage response), RVS (receiving voltage sensitivity) and FBW (fractional bandwidth) of underwater acoustic transducers. Influence of the design variables on the transducer performance was analyzed with equivalent circuits and the finite element method. When the piezocomposite is vibrating in a pure thickness mode, inter-pillar resonant modes are likely to occur between lattice-structured piezoceramic pillars and polymer matrix, which significantly deteriorate the performance of the piezocomposite. In this work, a new method to design the structure of the 1~3 type piezocomposite was proposed to maximize the TVR, RVS and FBW while preventing the occurrence of the inter-pillar modes. Genetic algorithm was used in the optimal design.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.220-223
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• 2001

Pb가 10% 과잉되고 Zr : Ti = 52 : 48 조성을 갖는 PZT sol이 Pt(3500Å)/Ti(400Å)/SiO₂(3000Å)Si(525㎛)기판 위에 스핀 코팅법으로 반복 코팅된 후, 450℃에서 10분, 650℃에서 2분간 반복 열처리되었다. 이와 같이 다양한 두께로 적층된 박막은 각 시편에 대해 최종적으로 650℃ 30분 동안 어닐링 처리되었다. 제조된 PZT 박막의 두께는 4100Å에서 1.75㎛사이의 4종이었다. 이어서 스퍼터링법으로 Pt전극이 PZT 막 위에 증착되었다. 제조된 PZT 박막의 결정 구조 조사를 위해 XRD, 그리고 미세 구조 및 전기적 특성을 알아보기 위해 FESEM과 P-E 이력 곡선이 각각 관찰되었다. 4100Å에서 1.75㎛까지 두께 증가에 따른 장비상의 포화 이력 한계로 잔류 분극(Pr)값이 25μC/㎠에서 다소 감소되었다. 측정된 X선 회절 결과에서 최초 4회 코팅시 perovskite 결정 구조로 성장한 결정립은 (111)배향이 우세하었으나, 두께가 증가됨에 따라 (111)/(110)값이 감소되었으며, 이를 통해 두께 증가에 따른 (111)배향성이 다소 감소됨을 알 수 있었다. 이상의 결과로부터 제조된 PZT 박막은 큰 힘과 높은 내전압 특성을 갖는 마이크로 압전 액츄에이터에 적용될 수 있을 것으로 생각되었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.56-59
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• 1997

SAW filters of transversal type were fabricated on some piezoelectric substrates of the LN 128$^{\circ}$ Y-X, LN 64$^{\circ}$Y-X, Quartz ST-cut wafers through the simulation in which the number o: IDT and window function were changed for the required frequency, and the mask making. Their IDT spacing and width were 3 ${\mu}{\textrm}{m}$, chip size was 4.462 $\times$ 2.086 mm$^2$, and they had double electrode transversal type IDTs. In addition to pure Al electrode devices, Ti thin films having the different thicknesses was introduced between the Al electrode and the substrate for improving the power resistance strength. They had 11-12 dB insertion losses similar to those of pure Al electrode SAW filters in case of LN 128$^{\circ}$ Y-X, LN 64$^{\circ}$ Y-X, meaning that Ti thin film was not detrimental to the insertion loss and general frequency properties. The filters had the center frequencies 162MHz for LN 128$^{\circ}$ Y-X, 186MHz for 64$^{\circ}$ Y-X, and 131MHz for Quartz ST-cut substrates.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.257-257
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• 2007

압전 액츄에이터의 효율적 작동을 위해서는 변위량이 크고 이력이 없으며 응답이 빠르고 온도특성이 좋아야 하는 등의 여러 조건들을 만족시켜야 한다. 따라서 본 실험은 압전 효율은 높이고 압전 손실은 낮추기 위하여 Pb$[(Mn_{1/3}Sb_{2/3})_{0.04}\;Zr_x\;Ti_y]O_3$, 세라믹스를 선정하였으며 Zr/Ti의 변화(x=0.47~0.5, y=0.46~0.49)에 따른 각각의 압전 특성 및 강유전 특성을 조사하였다. 일반적인 산화물 합성법을 이용하여 압전 분말을 제조하였고 EMAS standard(6001)에 근거하여 시편을 제조하였다. XRD 관찰결과 모든 조성에서 perovskite구조의 단일상만을 나타내는 소결체를 얻을 수 있었으며 FE-SEM 관찰결과 $1250^{\circ}C$의 소결시편이 $2-3{\mu}m$의 grain size를 갖는 치밀한 미세구조를 나타내었다. 가장 우수한 압전특성을 나타내는 조성은 Zr/Ti의 비가 0.485/0.475 조성이었으며 그때의 전기기계 결합계수(Kp) 값은 62.5%였고, 기계적 품질계수(Qm) 값은 1004였다.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.193-195
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• 1994

In this study, the structural, dielectric and piezoelectrical properties of $xPb(Mg_{1/2}W_{1/2})O_3-(1-x)[0.41Pb(Ni_{1/3}Nb_{2/3})O_3-0.36PbTiO_3-0.23P Zr)_3]$ (x=0, 0.01, 0.02, 0.03, 0.04, 0.05) system ceramics were investigated. The dielectric constant ${\varepsilon_{33}}^{\tau}$ at loon temperature increased up to 3mol% PMW and decreased with further PMW content. The specimen with 1mol% $Pb(Mg_{1/2}W_{1/2})O_3$, which has the ${\varepsilon_{33}}^{\tau}=5509$, kp=59[%] and $d_{33}=758{\times}10^{-12}[C/N]$, exhibits good characteristics.

• Electrical & Electronic Materials
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• v.10 no.2
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• pp.126-133
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• 1997

In order to apply for the gas sensing layer and the piezoelectric thin film devices, we studied the effects of magnetron sputtering conditions and annealing temperature on the electrical and structual characteristics of the ZnO thin film. The optimal deposition conditions, in order to obtain a c axis of the ZnO (002) phase thin film which is perpendicular to SiO$_{2}$/Si substrate, were like these ; substrate temperature 150.deg. C, chamber pressure 2 mtorr, R.F. power 300 watts, gas flow ratio 0.4[O$_{2}$(Ar + $O_{2}$)]. When the ZnO thin film was annealed in 600.deg. C, $O_{2}$ gas ambient for 1 hr, the resistivity was 2.6 x 10$^{2}$.ohm.cm and the grain size of ZnO thin film was less than 1 .mu.m. So the ZnO thin film acquired from above conditions can apply for the gas sensing layer which require a c axis perpendicular to the substrate surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.374-375
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• 2006

This paper describes anodic bonding characteristics of MCA to Si-wafer using evaporated Pyrex #7740 glass thin-films for MEMS applications. Pyrex #7740 glass thin-films with the same properties were deposited on MCA under optimum RF sputter conditions (Ar 100 %, input power $1\;W/cm^2$). After annealing at $450^{\circ}C$ for 1 hr, the anodic bonding of MCA to Si-wafer was successfully performed at 600 V, $400^{\circ}C$ in $110^{-6}$ Torr vacuum condition. Then, the MCA/Si bonded interface and fabricated Si diaphragm deflection characteristics were analyzed through the actuation and simulation test. It is possible to control with accurate deflection of Si diaphragm according to its geometries and its maximum non-linearity being 0.05-0.08 %FS. Moreover, any damages or separation of MCNSi bonded interfaces did not occur during actuation test. Therefore, it is expected that anodic bonding technology of MCNSi-wafers could be usefully applied for the fabrication process of high-performance piezoelectric MEMS devices.