• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.234-237
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• 2000

In this paper, the structural, dielectric and piezoelectric properties of the Pb[(S $b_{1}$2/N $b_{1}$2/)$_{0.035}$- $_Mn_{1}$3/N $b_{2}$3/)$_{0.065}$-(Z $r_{0.49}$, $Ti_{0.51}$)$_{0.90}$] $O_3$ ceramics were investigated with respect to the variation of the milling time. Grain size was decreased as the increase of milling time. As the milling time is increased, the particle size of the powder was decreased. Dielectric constant and electromechanical coupling factor (Qm)were slowly increased with the increase of milling time. The highest value of Qm was 1,497 at milling time 8 hour. Temperature coefficient of resonant frequency(TC $F_{r}$) was moved to positive side with the increase of milling time.e.e.e.e.e.e.

• 대한전기학회논문지
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• 제44권4호
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• pp.479-482
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• 1995

In this study, to improve sintering condition, anisotropic properties ( $k_{t}$/ $k_{p}$) of electromechanical coupling coefficient and piezoelectric constant $d_{h}$ and $g_{h}$, Mn $O_{2}$ impurity was added to the (P $b_{0.76}$C $a_{0.24}$)[( $Co_{1}$2/ $W_{1}$2/)$_{0.04}$ $Ti_{0.96}$] $O_{3}$ ceramics for application to hydrophone devices. Electromechanical coupling coefficients of the specimen with 1.5 [mol%] Mn $O_{2}$ sintered at 1150.deg. C were $k_{t}$=49% and $k_{p}$ = O, which exibited the highest value in piezoelectric anisotropic properties (kt/kp). Without relations with sintering temperature, the highest value of hydrostatic piezoelectric constant $d_{h}$ & $g_{h}$ were shown at the specimen with 1.5 [mol%] Mn $O_{2}$. Accordingly, the best addition amount of Mn $O_{2}$ was 1.5 [mol%] and proper sintering temperature was 1150.deg. C. Hydrostatic piezoelectric constant values of $d_{h}$=64.52[10$^{-12}$ C/N], $g_{h}$=35.92[10$^{-3}$ Vm/N] in the above condition were effectiely extended for hydrophone applications.pplications.ons.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2172-2179
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• 2002

In this paper, we examine the dynamic electromechanical behavior of an edge crack in a piezoelectric ceramic layer bonded between two elastic layers under the combined anti-plane mechanical shear and in-plane electric transient loadings. We adopted both the permeable and impermeable crack boundary conditions. Fourier transforms are used to reduce the problem to the solution of two pairs of dual integral equations, which are then expressed to a Fredholm integral equation of the second kind. Numerical values on the dynamic energy release rate are presented to show the dependences upon the geometry, material combination, electromechanical coupling coefficient and electric field.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.1117-1120
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• 1999

In this paper, we design the H$\infty$ optimal controller satisfying robust stability and performance in spite of the plant uncertainty for an electro-mechanical actuator system and analyze the controller in frequency domain. H$\infty$ optimal controller K was designed using iteration algorithm suggested by DOYLE. Using the controller in an electro-mechanical actuator system, the joint with very small coupling rigidity coefficient was used to vary the control parameter. The plant unstructured uncertainty was assumed to be a multiplicative type.

• 한국전기전자재료학회논문지
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• 제13권8호
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• pp.675-680
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• 2000

In this study the temperature coefficient of resonant frequency(TC $F_{r}$) dielectric and piezoelectric properties of Pb[(S $b_{1}$2//N $b_{1}$2/)$_{0.065}$)-(Z $r_{x}$, $Ti_{1-x}$ )$_{0.90}$] $O_3$ceramics were investigated with Zr/Ti ratio. The compositions near the morphotropic phase boundary (MPB) appeared when Zr/Ti ratio was 49.5/50.5 The dielectric constant and electromechanical coupling factor( $k_{p}$) also showed the highest values of 1,257, 0.653 respectively when the Zr/Ti ratio was 49.5/50.5 Moreover the mechanical quality factor( $Q_{m}$) showed th lowest value of 713 when the Zr/Ti ratio. The temperature coefficient of resonant frequency(TC $F_{r}$) abruptly change at the morphotropic phase boundary(MPB) which existed between the rhombohedral phase with highly negative TC $F_{r}$ of -106ppm/$^{\circ}C$ and the tetragonal phase with highly positive TC $F_{r}$ of +64pp $m^{\circ}C$ as Zr/Ti ratio varied from 50/50 to 49.5/50.5.50.5..50.5.

• 대한전자공학회논문지
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• 제11권6호
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• pp.1-15
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• 1974

본 연구는 탄성파 지연선에 이용되는 탄성표면파중에서 SH표면파 모우드에 대하여 이론적 해석을 하였으며 그 결과 전기-기계적 결합계수가 크며 또한 여전 매질내 깊이 방향으로 아주 작은 감쇠률을 갖고 표면을 따라 전파됨을 알았단. 예로서 PZT-4인 경우 에너지의 80%가 감쇠되는 깊이는 190파장이 된다. 또한 탄성표면파 지연선을 하나의 계단자강으로서 취급하여 삽입손실를 구하였으며 특히 SH표면파 모우드와 같이 전기-기계론 결합계수가 큰 경우는 인터디지탈 트랜스듀셔의 전극폭과 윤극간 간격 사이의 비에 따라 중심 주파수가 현저히 달라진다. 그리고 탄성파 지연선의 온도계수를 벌크파인 종파, 횡파에 대하여 구하였으며 LiTaO2 Z축방향 전파의 횡파는 지연시간의 온도계수가 5.4X10-6/℃로 아주 작아짐을 알았다. 또한 LiNbO3의 130°, 64° 로테이트 Y캇트, X전파의 탄성표면파의 온도계수가 이론치와 잘 일치함을 실험적으로 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.421-424
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• 2004

In this study, in order to develop low temperature sintering ceramics for ultrasonic vibrator, PNW-PMN-PZT system ceramics were manufactured with the amount of $CaCO_3$ addition and their piezoelectric, dielectric and microstructural characteristics were investigated. $CaCO_3$ addition to PNW-PMN-PZT basic composition was proved to be capable of sintering the ceramics at temperature below $1000^{\circ}C$ due to the effect of $Li_2CO_3-CaCO_3$ liquid phase. However, with increasing the amount of $CaCO_3$ addition, the second phase was appeared. As the results, electromechanical coupling coefficient (kp) and dielectric constant $(\epsilon_r)$ decreased. Taking into consideration electromechanical coupling coefficient (kp) of 0.49, mechanical quality factor (Qm) of 1396, dielectric constant $(\epsilon_r)$ of 1300 and density of $7.78[g/cm^2]$, it was concluded that the 0.25wt% $CaCO_3$ addition composition ceramics sintered at $920^{\circ}C$ was suitable for ultrasonic vibrator application.

• E2M - 전기 전자와 첨단 소재
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• 제10권1호
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• pp.20-25
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• 1997

In this study, piezoelectric actuator samples were fabricated using 0.375PMN-0.37OPT-0.255PZ system ceramics with Barium substitution and the strain properties of them were investigated. Dielectric constant of the specimens increased with the increase of Ba content up to 5mol% and decreased with futher addition of Ba. The largest piezoelectric coefficient and electromechanical coupling coefficient were observed at the sintering temperature of 1250'C and Barium content of 5mol%. The characteristics of strain hysteresis was found largely with varing the sintering temperature on the single round type, and the strain is proportional to piezoelectric coefficient.

• 한국세라믹학회지
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• 제40권4호
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• pp.393-397
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• 2003

To investigate the effect of AIN c-axis orientation on the resonance performance of film bulk acoustic wave resonators, solidly mounted resonators with crybtallographically different AIN piezoelectric films were prepared by changing only the bottom electrode surface conditions. As increasing the degree of c-axis texturing, the effective electromechanical coupling coefficient ($\kappa$$\_$eff/)$^2$ in resonators increased gradually. The least 4 degree of full width at half maximum in an AIN(002) rocking curve, which corresponds to $\kappa$$^2$$\_$eff/ of above 5%, was measured to be necessary for band pass filter applications in wireless communication system. The longitudinal acoustic wave velocity of AIN films varied with the degree of c-axis texturing. The velocity of highly c-axis textured AIN film was extracted to be about 10200 n/s by mathematical analysis using Matlab.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1723-1725
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• 1999

This paper is the study for piezoelectric properties of PMN-PT-PZ composition for high power piezoelectric device. It needs the properties such as high mechanical quality factor(Qm), high electromechanical coupling coefficient(kp) and high dielectric strain constant$(d_31)$, and the stable electromechanical properties under high vibration level. For acquiring this results, the value of x is changed in 0.1Pb$(Mn_{1/3}Nb_{2/3})O_3$+(0.9-x)$PbZrO_3+xPbTiO_3$ composition to find MPB(morphotropic phase boundary), and the piezoelectric constants is measured by resonance-antiresonance frequency method, based on IRE Standard. Also, it is measured as a function of the amount of additive, $Nb_2O_5$. When the composition is applied to high power device, the electromechanical properties is measured by laser vibrometer to confirm the reliablity under high vibration level. From these results, PMN-PT-PZ composition is shown excellent properties and capacity of application to high power device.