• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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• pp.637-640
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• 2017

In this study, $(1-x)(Na_{0.52}K_{0.443}Li_{0.037})(Nb_{0.883}Sb_{0.08}Ta_{0.037})O_3-x(Bi_{0.5}(Na_{0.7}K_{0.3})_{0.5}ZrO_3$ ceramics were fabricated by BNKZ substitution using a conventional solid-state method to develop excellent lead-free piezoelectric ceramics for piezoelectric actuators; their dielectric and piezoelectric properties were then investigated. All specimens were in the orthorhombic phase. $NKL-NSTO_3$ ceramics with x=0.01 showed excellent piezoelectric properties. The density (${\rho}$), piezoelectric charge constant ($d_{33}$), planar piezoelectric coupling coefficient ($k_p$), mechanical quality factor ($Q_m$), and dielectric constant (${\varepsilon}_r$) had optimized values of $4.56g/cm^3$, 208 pC/N, 0.43, 96, and 975, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.333-334
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• 2006

The objective of this study is to fabricate a piezoelectric composite consisting of a piezoelectric ceramic and a high toughness material and to evaluate their electromechanical properties for high force actuator applications. The mixture of the piezoelectric material, PMNZT, and high toughness material, $ZrO_2$, exhibited high piezoelectric properties as well as good mechanical fracture resistance. Up to 2 vol% of $ZrO_2$ in PMNZT matrix, piezoelectric $d_{33}$ coefficient was above 400 pC/N, being 80% of that for the original PMNZT, and the toughness showed twice of the PMNZT. When the volume fraction of the $ZrO_2$ was above 5%, however, the piezoelectric coefficient became abruptly decreased and it approached 20% of value for the PMNZT.

• Journal of Powder Materials
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• v.17 no.5
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• pp.404-408
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• 2010

The effects of high energy ball-milling (HEBM) on the sintering behavior and piezoelectric properties of 0.1 wt% $Li_2CO_3$ doped 0.8Pb($Mg_{1/3}Nb_{2/3}$)$O_3$-0.2Pb($Zr_{0.475}Ti_{0.525}$)$O_3$ (PMN-PZT) ceramics were investigated. It was found that HEBM treatment was quite effective to reduce the average particle size down to 300 nm, leading to increased density as well as enhanced piezoelectric properties of a sintered specimen even though prolonged HEBM resulted in unwanted secondary phases that caused a degradation of piezoelectric properties. The dielectric constant ($\varepsilon_r$), piezoelectric coupling factor ($k_p$) and piezoelectric constant $d_{33}$ of 0.1 wt% $Li_2CO_3$ doped PMN-PZT ceramics prepared via HEBM for 10 h reached 2040, 0.68 and 554 pC/N, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.420-425
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• 2012

Lead-free piezoelectric ceramic/epoxy composites with '0-3' connectivity were prepared by cold-pressing with a temperature controlled curing method. A ceramic powder with a composition of $(Na_{0.51}K_{0.47}Li_{0.02})(Nb_{0.8}Ta_{0.2})O_3$ was synthesized by a conventional solid state reaction route. The dielectric and piezoelectric properties of ceramic/epoxy composites were characterized as a function of the volume fraction (${\phi}$) of piezoelectric ceramics, which was varied from 70 to 95 vol%. The results indicated that the piezoelectric properties of composites were significantly affected by the volume fraction of ceramics. In terms of the piezoelectric properties, specimens showed the best performance at ${\phi}$= 85 vol%, resulting in the piezoelectric constant $d_{33}$ of 39 pC/N and the figure of merit as a piezoelectric energy harvester ($d_{33}{\cdot}g_{33}$) of 1.24 $pm^2/N$.

• The Korean Journal of Ceramics
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• v.5 no.2
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• pp.171-177
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• 1999

In the $(Pb_{1-x}M_x)[(Mn_{1/3}Sb_{2/3})_{0.05}Zr_yTi_{0.95-y}]O_3$ system, where M=Ca and Sr, the piezoelectric properties were evaluated to examine the possibility of application to piezoelectric transformer. A Rosen-type piezoelectric transformer was formed, then the electrical properties of voltage step-up ratio, frequency characteristics etc. were analysed. The morphotropic phase boundary was determined to be y=0.475 in $Pb[(Mn_{1/3}Sb_{2/3})_{0.05}Zr_yTi_{0.95-y}]O_3$ system and the piezoelectric properties of this composition was kp=0.59, Qm=1600 and $\varepsilon_r$=1150. Moreover, when 1-2 mol% of Sr are substituted, enhanced piezoelectric properties of kp=0.61, Qm=1600 and $\varepsilon_r$=1400 were shown. The temperature rising (ΔT) of a piezoelectric transformer with $Pb[Mn_{1/3}Sb_{2/3})_{0.05}Zr_{0.475}Ti_{0.475})]O_3 $ composition was $10^{\circ}C$, and the voltage step-up ratio was 500 when the output voltage was 4000V, whereas the ΔT was below $3^{\circ}C$ and the resonant frequency variation ($\Delta f_r$) as a function of load resistance was below 5% when the output voltage was 2000 V. These characteristics are superior to the properties of materials, which were substituted by Ca or without substitution.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.3
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• pp.152-155
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• 2018

Ultrasonic wave technologies have been widely used in ultrasonic washing machines, ultrasonic surgery, ultrasonic welding machines, ultrasonic sensors, and medical instruments. Ultrasonic surgery can be realized through the cavitation effect of ultrasonic waves. In this study, piezoelectric ceramics were manufactured to achieve the optimum design of a piezoelectric vibrator in a handheld generator for ultrasonic surgery. The best specimen showed the excellent piezoelectric properties of kp＝0.624, Qm＝1,531, and $d_{33}=356pC/N$. Numerical modeling based on the finite element method was performed to find the resonance frequency, the anti-resonance frequency, and the displacement properties of the handheld ultrasonic generator. Maximum displacement was observed in the six-step piezoelectric vibrator at $6.36{\mu}m$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.225-227
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• 2006

Multilayer step down piezoelectric transformers were manufactured using PZN-PMN-PZT and PMN-PNN-PZT ceramics respectively. Sintering temperature of the ceramics was $940^{\circ}C$. And then. their electrical properties were investigated according to the variations of frequency and load resistance. The voltage step-up ratio of multilayer piezoelectric transformer showed the maximum values in the vicinity of 69 and 71kHz, respectively. At the load resistance of $100{\Omega}$, the piezoelectric transformers showed the temperature rises of about 21 and $18^{\circ}C$ at the output power of 15W and 18W, respectively. At the transformer with high effective electromechanical coupling factor($k_{eff}$), lower temperature increase was appeared.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.7
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• pp.597-601
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• 2002

In this study, the structural, dielectric and piezoelectric properties of $Pb[(Ni_{1/3}Nb_{2/3})_x-(Mn_{1/3}Nb_{2/3})_{0.09-x}-(Zn_{0.505}Ti_{0.495)_0.91]O_3$ (x=0, 0.01, 0.02, 0.03, 0.04, 0.05) system ceramics were investigated to develop the composition ceramics for piezoelectric transformer. All the specimens were sintered at $1250^{\circ}C$ and its physical properties were measured, and the results are as follows : With increasing PNN substitution for PMN-PZT system, dielectric constant was increased and electro-mechanical coupling factor($k_p$) was increased to 0.62 at 5 mol% while mechanical quality factor(Qm) was decreased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.19-23
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• 2018

In a Pb-included piezoelectric composition, $Sr_yPb_{1-y}[(Zn_{1/3}Nb_{2/3})_x-(Ni_{1/3}Nb_{2/3})_{0.2}-(Zr_{0.46}Ti_{0.54})_{0.8-x}]O_3$ was selected in order to attain high piezoelectric properties. According to the PZN ratio (x) and the amount of Sr doping (y), the crystal structure, microstructure and piezoelectric properties were measured and evaluated. In the case of Sr 4 mol% doping, the piezoelectric properties were the highest for a PZN ratio of 0.1. In this condition, the grain size was larger and the intensity was higher. With the PZN ratio fixed and varying the Sr doping, the piezoelectric properties increased until 10 mol% doping and then decreased for over 12 mol% doping. In the case of x＝0.1 and y＝10 mol%, the best piezoelectric properties were obtained, i.e., $d_{33}=660pC/N$ and $k_p=68.5%$, and these values seem to be related to the grain size and crystal structure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.8
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• pp.632-635
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• 2011

Additions (ZnO, CuO) doped $0.98(Na_{0.5}K_{0.5})NbO_3-0.02Li(Sb_{0.17}Ta_{0.83})O_3$ (0.98NKN-0.02LST-x) lead free piezoelectric ceramics have been fabricated by ordinary sintering technique. The effects of additions doping on the dielectric, piezoelectric, and ferroelectric properties of the ceramics were mainly investigated. X-ray diffraction of the sample appeared orthorhombic phase. The specimen doped with additions exhibits enhanced electrical properties ($d_{33}$= 153 pC/N). These results indicate that the 0.98NKN-0.02LST-x ceramics is a promising candidate for lead-free piezoelectric ceramics for applications such as piezoelectric actuators, harmonic oscillator and so on.