• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.90-94
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• 2016

In this work, [$Pb(Mg_{1/2}W_{1/2})_{0.03}(Ni_{1/3}Nb_{2/3})_x(Zr_{0.5}Ti_{0.5})_{0.97-x}O_3-BiFeO_3$] (x=0.02 to 0.12) composition ceramics were fabricated by the conventional soild state reaction method and their microstructure and piezoelectric properties were investigated according to PNN substitution. The addition of small amount of $BiFeO_3$, $Li_2CO_3$, and $CaCO_3$ were used in order to decrease the sintering temperature of the ceramics. The XRD (x-ray diffraction patterns) of all ceramics exhibited a perovskite structure. The sinterability of PMW-PNN-PZT-BF ceramics was remarkably improved using liquid phase sintering of $CaCO_3$, $Li_2CO_3$. However, it was identified from of the X-ray diffraction patterns that the secondary phase formed in grain boundaries decreased the piezoelectric properties. According to the substitution of PNN, the crystal structure of ceramics is transformed gradually from a tetragonal to rhombohedral phase. The x=0.10 mol PNN-substituted PMW-PNN-PZT-BF ceramics sintered at $920^{\circ}C$ showed the optimum values of piezoelectric constant($d_{33}$), piezoelectric figure of merit($d_{33{\cdot}}g_{33}$), planar piezoelectric coupling coefficient($k_p$) and density : $d_{33}=566$ [pC/N], $g_{33}=29.28[10^{-3}mV/N]$, $d_{33{\cdot}}g_{33}=16.57[pm^2/N]$, $k_p=0.61$, density=7.82 [$g/cm^3$], suitable for duplex ultrasonic sensor application.

• Structural Engineering and Mechanics
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• v.73 no.3
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• pp.259-269
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• 2020

In this paper, bending-stretching analysis of thick functionally graded piezoelectric rectangular plates is studied using the higher-order shear and normal deformable plate theory. On the basis of this theory, Legendre polynomials are used for approximating the components of displacement field. Also, the effects of both normal and shear deformations are encountered in the theory. The governing equations are derived using the principle of virtual work and variational approach. It is assumed that plate is made of piezoelectric materials with functionally graded distribution of material properties. Hence, exponential function is used to modify mechanical and electrical properties through the thickness of the plate. Finally, the effect of material properties, electrical boundary conditions and dimensions are investigated on the static response of plate. Also, it is shown that results of the presented model are close to the three dimensional elasticity solutions.

• Journal of the Korean Ceramic Society
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• v.34 no.5
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• pp.461-466
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• 1997

Dielectric and piezoelectric properties of (Pb1-1.5xLnx)(Ti0.98Mn0.02)O3 ceramics with x=0~0.2 have been investigated. Pb(Ti0.98Mn0.02)O3 showed poor sinterability and cracking on cooling, but the substitution of Nd3+ ions into Pb2+ sites resulted in dense microstructures without cracking through reducing crystallographic anisotropy. The Nd3+ substitution, however, deteriorated the temperature stability of the piezoelectric properties because of lowering the Curie point. Electromechanical anisotropy(Kt/Kp) indicated a maximum value of 10 when x=0.1. This result might be attributed to the counteracting effects that with increasing x, the lattice anisotropy decreases while the poling becomes easier due to the increase in O2- vacancy concentration. Thickness-shear mode resonators with (Pb0.85Nd0.1)(Ti0.98Mn0.02)O3 composition showed good resonant characteristics around 4.5 MHz.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.465-468
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• 2004

The performance of the piezoelectric patches as vibration control elements depends on the shunting electronics which are designed to dissipate vibration energy through a resistive element. In this study, tuning of the shunting circuits is performed based on the wave propagation characteristics. Optimization of the electronic component is performed depending on the dynamic and geometric properties which include boundary conditions and position of the shunted piezoelectric patch relative to the structure. The developed tuning methods showed superior capabilities in minimizing structural vibration and noise radiation compared to other tuning methods. The tuned circuits are relatively insensitive to changes in modal properties and boundary conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.104-108
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• 2013

In this paper, the $0.95(Na_{0.5}K_{0.5})_{0.04}[(Nb_{0.8}Ta_{0.20})_{0.994}Co_{0.015}]O_3$(abbreviated as NKNT) + $0.05KNbO_3$ lead-free piezoelectric ceramics were synthesized by the conventional mixed oxide method route with normal sintering. And also, the effects of calcination temperature on the microstructure, dielectric properties, and piezoelectric properties were investigated. A polymorphic phase transition(PPT) between orthorhombic and tetragonal phases was observed in specimens calcined at $810^{\circ}C{\sim}850^{\circ}C$. The ceramics calcined at $830^{\circ}C$ showed excellent piezoelectric properties: $d_{33}$= 179 pC/N, $k_p$= 0.384, $Q_m$= 79.73). These results indicate that the ceramic is a promising candidate material for lead-free piezoelectric ceramics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.271-271
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• 2006

The structural, dielectric and piezoelectric properties of $[Bi_{1-x}(Na_{0.7-x}K_{0.2}Li_{0.1})]_{0.5}BaxTiO_3$ (BNKLBxT) ceramics were studied for the compositional range, x = 0-0.08. The samples were prepared by conventional sintering technique. The result of X-ray diffraction (XRD) suggest that $Ba^{2+}$ diffuse into the $[Bi(Na_{0.7}K_{0.2}Li_{0.1})]_{0.5}TiO_3$ (BNKLT) lattices to form a solid solution with a single phase perovskite structure. The ceramic show excellent piezoelectric and ferroelectric properties, and optimum properties measured are as follows: piezoelectric constant $d_{33}=230pC/N$, planar electromechanical coupling factor $k_p\;=\;40.3%$, remanent polarization $P_r\;=\;30\;{\mu}C/cm^2$, and coercive field $E_c\; =\;2.5\;kV/mm$, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.5
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• pp.471-479
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• 2022

Recently, piezoelectric devices, such as ultrasonic surgery, ultrasonic atomizer, and ultrasonic speaker, are analyzed and designed by finite element simulation methods. However, the discrepancy between the design and the experiment results of the device typically occurs due to the inaccuracy of the piezoelectric material properties. To improve the simulation accuracy, the material properties of the PZT ceramics were better refined using parameter estimation method. The material parameters are elastic stiffness c^E_ij and piezoelectric constant e_ij of PZT ceramics. The impedance curve characteristics for the LTE mode of PZT ceramics were calculated. The mismatch between the simulation and the experimental data were compared and minimized by a least square method. Finally, the simulated impedance data were compared with the experimental data for the various vibration modes of PZT ceramics and the optimized material properties of PZT ceramics were verified. To further verify the accuracy, this method was also applied to piezoelectric PMN-PT single crystals.

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1582-1589
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• 2004

The dynamic response of an eccentric Griffith crack in functionally graded piezoelectric ceramic strip under anti-plane shear impact loading is ana lysed using integral transform method. Laplace transform and Fourier transform are used to reduce the problem to two pairs of dual integral equations, which are then expressed to Fredholm integral equations of the second kind. We assume that the properties of the functionally graded piezoelectric material vary continuously along the thickness. The impermeable crack boundary condition is adopted. Numerical values on the dynamic stress intensity factors are presented for the functionally graded piezoelectric material to show the dependence of the gradient of material properties and electric loadings.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.1
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• pp.12-19
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• 2001

In this study, the physical properties of the piezoelectric sounder with metal-piezoelectric ceramics were analyzed. The dielectric and piezoeletric properties of 0.5wt% MnO$_2$ and NiO doped 0.1Pb(Mg$\_$1/3/Nb$\_$2/3/)O$_3$-0.45PbTiO$_3$-0.45PbZrO$_3$ ceramics were investigated aiming at acoustic transducer applications. The acoustic characteristics of a thin circular disc-type with metal-piezoceramics have been investigated. Also, the acoustic characteristics for the geometrical form of case were investigated. The piezoelectric sounder with 200kHz resonant frequency and 20kHz bandwidth was designed by considering the sharp directivity and the sound pressure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.217-218
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• 2006

In this study, In order to develop the low temperature sintering multilayer piezoelectric actuator, PMN-PNN-PZT system ceramics were manufactured with the sintering temperature, and their microstructure and piezoelectric properties were investigated. At the composition ceramics sintered at $900^{\circ}C$, dielectric constant(${\varepsilone}_r$), electromechanical coupling factor($k_p$), piezoelectric constant($d_{33}$) and mechanical quality factor(Qm) showed the optimal value of 1095, 0.60, 363 and 1055, respectively, for multilayer piezoelectric actuator application.