• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.869-872
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• 2007

In this study, in order to develop low temperature sintering ultrasonic nozzle, single-layer and multilayer ring-type piezoelectric actuators were manufactured using PMN-PNN-PZT ceramics, And then the electrical properties were investigated. A ring-type piezoelectric actuator was modeled by ATILA program using finite element method(FEM). The piezoelectric actuator dimension was $\Phi26.5$ (outer diameter), $\Phi12$ (inner diameter), 3.5 mm (thickness). By FEM analysis, resonant and anti-resonant frequencies were appeared as 56.7 kHz and 61.5 kHz. The displacement increased with the increases of the number of layer. Based on the result, ring-type multilayer piezoelectric actuators were manufactured at low co-firing temperature of $940^{\circ}C$. The resonant resistance decreased with the increases of the number of layer. And also, the capacitance increased with the increases of the number of layer. The mechanical quality factor (Qm) decreased with the increases of the number of layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.13-22
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• 1999

Both the resonance and ultrasonic techniques are standard methods far characterizing the physical properties of piezoelectric materials. However, we found that each technique can only offer a few reliable measurements while the rest often have errors or impossible to implement because of the sample requirements. This paper show that one can use the combination of both techniques to achieve much better accuracy and be able to get the complete set of elastic, dielectric and piezoelectric coefficients using fewer samples. Using an ultrasonic spectroscopy we have also measure the dispersion of the ultrasonic velocity and the attenuation up to 65 MHz. Pb(Zr,Ti)O$_3$[PZT] ceramics were used as examples fur both studies.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.9
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• pp.495-501
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• 2000

This paper presents a method to minimize the initial deflection of a multi-layer piezoelectric microactuator without loosing its piezoelectric deflection performance required for light modulating micromirror devices. The multi-layer piezoelectric actuator composed of PZT silicon nitride and platinum layers deflects or buckles due to the gradient of residual stress. Based on the structural analysis results and relationship between process conditions and mechanical properties we have modified the fabrication process and the thickness of thin film layers to reduce the initial residual stress deflection without decreasing its piezoelectric deflection performance. The modified designs fabricated by surface-micromachining process achieved the 77% reduction of the initial deflection compared with that of the conventional method based on the measured micromechanical material properties is applicable to the design refinement of multi-layer MEMS devices and micromechanical structures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.250-250
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• 2007

In this paper, multilayer piezoelectric transformer for high power is presented. This piezoelectric transformer, with a multilayered construction in the thickness direction, was fabricated at the sintering temperature of $1055^{\circ}C$. The electrical properties of multilayer piezoelectric transformer as a function of Internal electrode structure, with same size, were investigated. Also, the multilayer piezoelectric transformer with different layer number of 5, 10, 15 layers, were investigated.

• Korean Journal of Materials Research
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• v.22 no.1
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• pp.35-41
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• 2012

Presently, the most promising family of lead-free piezoelectric ceramics is based on $K_{0.5}Na_{0.5}NbO_3$(KNN). Lithium, silver and antimony co-doped KNN ceramics show high piezoelectric properties at room temperature, but often suffer from abnormal grain growth. In the present work, the $(Ba_{0.85}Ca_{0.15})(Ti_{0.88}Zr_{0.12})O_3$ component, which has relaxor ferroelectric characteristics, was doped to suppress the abnormal grain growth. To investigate this effect, Lead-Free $0.95(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}NbO_3-(0.05-x)AgSbO_3-x(Ba_{0.85}Ca_{0.15})(Ti_{0.88}Zr_{0.12})O_3$[KNLN-AS-xBCTZ] piezoelectric ceramics were synthesized by ball mill and nanosized-milling processes in lead-Free $0.95(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}NbO_3-(0.05-x)AgSbO_3$ in order to suppress the abnormal grain growth. The nanosized milling process of calcined powders enhanced the sintering density. The phase structure, microstructure, and ferroelectric and piezoelectric properties of the KNLN-AS ceramics were systematically investigated. XRD patterns for the doped and undoped samples showed perovskite phase while tetragonality was increased with increasing BCZT content, which increase was closely related to the decrease of TO-T. Dense and uniform microstructures were observed for all of the doped BCZT ceramics. After the addition of BCTZ, the tetragonal-cubic and orthorhombic-tetragonal phase transitions shifted to lower temperatures compared to those for the pure KNNL-AS. A coexistence of the orthorhombic and tetragonal phases was hence formed in the ceramics with x = 0.02 mol at room temperature, leading to a significant enhancement of the piezoelectric properties. For the composition with x = 0.02 mol, the piezoelectric properties showed optimum values of: $d_{33}$ = 185 pC/N, $k_P$ = 41%, $T_C=325^{\circ}C$, $T_{O-T}=-4^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.771-775
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• 2010

In this study, piezoelectric and dielectric properties of the $(Na_{0.5}K_{0.5})NbO_3-(1-x)(Bi_{0.5}Na_{0.5})TiO_3-xBaTiO_3$ [NKN-(1-x)BNT-xBT] ceramics were investigated. The lead-free NKN-(1-x)BNT-xBT ceramics were fabricated by a conventional mixed oxide method. The results indicate that the addition of $BaTiO_3$ significantly influences the sintering, microstructure, phase transition and electrical properties of NKN-BNT ceramics. A gradual change in the piezoelectric and dielectric properties was observed with the increase of BT contents. The dielectric constant, piezoelectric constant ($d_{33}$) and electromechanical coupling factor ($k_p$) increased at the morphotropic phase boundary (MPB). The $d_{33}$=184 pC/N, $k_p$=0.38, dielectric constant=1455 with dielectric loss value of less than 1% were obtained for the NKN-0.95BNT-0.05BT ceramics sintered at $1150^{\circ}C$ for 2h. These results demonstrate that the NKN-(1-x)BNT-xBT ceramics is an attractive candidate for lead-free piezoelectric materials.

• Journal of Ocean Engineering and Technology
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• v.24 no.6
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• pp.81-85
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• 2010

The effects of co-doping with complex dopants of softeners, $La^{+3}$ and/or $Nb^{+5}$, and a hardener, $Fe^{+3}$, on the microstructural and piezoelectric properties of PZT ceramics with a composition of a rhombohedral-tetragonal morphotropic phase boundary, $PbZr_{0.53}Ti_{0.47}O_3$, were investigated. Unlike single-element doping, the complex doping of both the softener and hardener ions led to various compensation effects for the piezoelectric properties of the PZT ceramics. For 0.5 wt.% $La_2O_3$ softener and/or 0.5 wt.% $Nb_2O_5$ doped compositions, there were apparent hardener doping (compensation) effects for an addition of over 1.0 wt.% $Fe_2O_3$. For the $La_2O_3$ and/or $Nb_2O_5$ doped composition, the co-dopant $Fe_2O_3$ addition led to lower kp and $\varepsilon$r, and increased $Q_m$ values. The prepared PZT ceramics modified with complex soft dopants, $La^{+3}$ and $Nb^+$, as well as a hard dopant, $Fe^{+3}$, showed that the piezoelectric properties were stable with the compositional variations, which made it possible to establish piezoelectric performances with higher reliability and reproducibility. The most improved piezoelectric properties of enhanced $Q_m$ with $\varepsilon_r$ remaining higher $k_p$, were obtained in the PZT composition complexly doped with $La^{+3}$ and $Fe^{+3}$. From the results obtained in this study, the properties of compositionally modified PZT ceramics can also be tailored over a wider range by changing the dopant compositions to meet the specific requirements for underwater or other applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.5
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• pp.445-451
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• 2022

Ultrasonic sensor is suitable as a next-generation autonomous driving assist device because its lower price compared to that of other sensors and its sensing stability in the external environment. Although Pb(Zr, Ti)O₃ (PZT)-relaxor ferroelectric system has excellent piezoelectric properties, the change in capacitance is large in the daily operating temperature range due to the low phase transition temperature. Recently, many studies have been conducted to improve the temperature stability of ferroelectric ceramics by controlling the grain size and crystal structure, so it is necessary to study the effect of the grain size on the piezoelectric properties and the temperature stability of PZT-relaxor ferroelectric system. In this study, the piezoelectric properties, phase transition temperature, and temperature coefficient of capacitance (TCC) of 0.9 Pb(Zr_1-xTi_x)O₃-0.1 Pb(Zn_1/3Nb_2/3)O₃ (PZT_x-PZN) ceramics with various grain sizes were investigated. PZT_x-PZN ceramics with larger grain size showed higher piezoelectric properties and temperature stability, and are expected to be suitable for ultrasonic devices in the future.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.846-851
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• 2017

Piezoelectricity is the capability of a piezoelectric material to change mechanical energy into electrical energy. The determination of electrical and mechanical properties plays a significant role in characterizing the piezoelectric material. The energy losses characteristics of piezoelectric material can be described by mechanical quality factor. In this paper, the output voltage and mechanical quality factor of Lead Zirconate Titanate (PZT-4A) piezoelectric material is determined under various resistance and loading conditions by using the test setup. The commercial FEM software ABAQUS is used to analyze the performance of piezoelectric material under static loading conditions. It is observed that these properties affect the performance of a material particularly in the designing of smart structures. The experimental results are partially compared to the simulation values.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1439-1441
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• 2001

In this paper, the piezoelectric and dielectric properties as a function of x and r in $yPbZr_xTi_{1-x}O_3-(1-y)Pb(Mn_{1/3}Nb_{2/3})O_3$ piezoelectric ceramics is investigated. As a results, when y is 0.95 and x is 0.505, electromechanical coupling factor($k_p$), permittivity(${{\varepsilon}_{33}}^T/{\varepsilon}_0$), piezoelectric strain constant($d_{33}$) and mechanical quality factor($Q_m$) are 58[%], 1520, 272 [pC/N] and 1550, respectively. From XRD analysis, when x is 0.505, it is MPB which present rhombohedral and tetragonal phase in same quantity. Also, From SEM observation. when sintering temperature is 1150[$^{\circ}C$], grain size is about 2 [${\mu}m$]. As y decreases, piezoelectric and dielectric properties and curie temperature decreases, but mechanical quality factor and sintering temperature increases.