• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.272-273
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• 2007

In this paper, ultrasonic nozzle and driving circuit were manufactured, respectively. And then, their electrical properties. were investigated. Ultrasonic nozzle was fabricated using PSN-PMN-PZT ceramics showing excellent piezoelectric characteristics. In order to drive ultrasonic nozzle, PWM controller(KA3525A) was used. The purpose of this study is to find the optimal driving condition of ultrasonic. nozzle. Accordingly electrical and temperature characteristic of ultrasonic driving system were investigated as a function of the input voltage.

• 한국산학기술학회논문지
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• 제6권6호
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• pp.457-460
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• 2005

금속 알콕사이드의 가수분해법인 졸-겔 공정을 이용하여 일차로 $TiO_2$와 $ZrO_2$ 나노 입자를 합성하고 난 후 $TiO_2$ 나노입자와 PbO를 혼합하여 $PbTiO_3$의 나노 입자를 얻었다. 2차 공정으로 나노입자 크기의 $ZrO_2$와 혼합하여 최종적으로 $PbZrTiO_3(PZT)$ 분말을 합성하였다. 소결된 압전체의 결정상을 분석하기 위하여 X-선 회절분석을 시행하였으며, 소결전 합성분말의 모양과 크기를 투과전자현미경을 이용하여 관찰하였으며 $900^{\circ}C$의 저온에서 소결한 $PbZrTiO_3$시편의 미세조직을 관찰하기 위하여 주사전자현미경을 이용하였다. 합성된 입자들의 크기는 각각 $TiO_2$는 약 20 ${\~}$ 30nm, $ZrO_2$는 15${\~}$30nm이였으며, $900^{\circ}C$ 저온에서 소결한 PZT 시편의 SEM 관찰결과 평균 입경은 $2{\~}4{\mu}m$의 페로 브스카이트 결정으로 치밀한 조직을 나타내었으며, 우수한 압전 특성도 나타내었다.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권3호
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• pp.102-110
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• 2005

Piezoelectric transformers(PT) are expected to be small, thin and highly efficient, and which are attractive as a transformer with high power density for step down voltage. For these reasons, we have attempted to develop a step-down PT for the miniaturized adaptor. We propose a PT, operating in thickness extensional vibration mode for step-down voltage. This PT consists of a multi-layered construction in the thickness direction. In order to develop the step-down PT of 10 W class and turn ratio of 0.1 with high efficiency and miniaturization, the piezoelectric ceramics and PT designs are estimated with a variety of characteristics. The basic composition of piezoelectric ceramics consists of ternary yPb(Zr$_{x}$Ti$_{1-x}$)O$_{3}$-(1-y)Pb(Mn$_{1/3}$Nb1$_{1/3}$Sb$_{1/3}$)O$_{3}$. In the piezoelectric characteristics evaluations, at y=0.95 and x=0.505, the electromechanical coupling factor(K$_{p}$) is 58$\%$, piezoelectric strain constant(d$_{33}$) is 270 pC/N, mechanical quality factor(Qr$_{m}$) is 1520, permittivity($\varepsilon$/ 0) is 1500, and Curie temperature is 350 $^{\circ}C$. At y = 0.90 and x = 0.500, kp is 56$\%$, d33 is 250 pC/N, Q$_{m}$ is 1820, $\varepsilon$$_{33}$$^{T}$/$\varepsilon$$_{0}$ is 1120, and Curie temperature is 290 $^{\circ}C$. It shows the excellent properties at morphotropic phase boundary regions. PZT-PMNS ceramic may be available for high power piezoelectric devices such as PTs. The design of step-down PTs for adaptor proposes a multi-layer structure to overcome some structural defects of conventional PTs. In order to design PTs and analyze their performances, the finite element analysis and equivalent circuit analysis method are applied. The maximum peak of gain G as a first mode for thickness extensional vibration occurs near 0.85 MHz at load resistance of 10 .The peak of second mode at 1.7 MHz is 0.12 and the efficiency is 92$\%$.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.216-220
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• 2018

The piezoelectric properties of $0.65Pb(Zr_{1-x}Ti_x)O_3-0.35Pb(Zn_{1/6}Ni_{1/6}Nb_{2/3})O_3$ ($PZT_x-PZNN$) ceramics with $0.530{\leq}x{\leq}0.555$ were investigated for application to piezoelectric energy harvesters. Although a morphotropic phase boundary (MPB) was found at approximately x = 0.545, the ceramic with the highest figure of merit (FOM) ($d_{33}{\times}g_{33}$) was observed at a composition of x = 0.540. Values of this figure of merit, $d_{33}{\times}g_{33}$, of $19.6pm^2/N$ and $20.2pm^2/N$ were obtained from $PZT_{0.540}-PZNN$ ceramics sintered at $920^{\circ}C$ and $950^{\circ}C$, respectively. A high output power of $937{\mu}W$ and a high power density of $3.3mW/cm^3$ were obtained from unimorph-type piezoelectric energy harvesters fabricated using $PZT_{0.540}-PZNN$ ceramic sintered at $920^{\circ}C$ for 4h.

• 한국재료학회지
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• 제29권4호
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• pp.205-210
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• 2019

$Pb(Zr,Ti)O_3$ (PZT) is used for the various piezoelectric devices owing to its high piezoelectric properties. However, lead (Pb), which is contained in PZT, causes various environment contaminations. $(K,Na)NbO_3$ (NKN) is the most well-known candidate for a lead-free composition to replace PZT. A single crystal has excellent piezoelectric-properties and its properties can be changed by changing the orientation direction. It is hard to fabricate a NKN single crystal due to the sodium and potassium. Thus, $(Na,K)NbO_3-Ba(Cu,Nb)O_3$ (NKN-BCuN) is chosen to fabricate the single crystal with relative ease. NKN-BCuN pellets consist of two parts, yellow single crystals and gray poly-crystals that contain copper. The area that has a large amount of copper particles may melt at low temperature but not the other areas. The liquid phase may be responsible for the abnormal grain growth in NKN-BCuN ceramics. The dielectric constant and tan ${\delta}$ are measured to be 684 and 0.036 at 1 kHz in NKN-BCuN, respectively. The coercive field and remnant polarization are 14 kV/cm and $20{\mu}C/cm^2$.

• 세라미스트
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• 제23권1호
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• pp.89-100
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• 2020

Abnormally large electromechanical strain properties have been reported in bismuth-based piezoelectric ceramics, which cast a promise for replacing the market-dominating PZT-based piezoelectric ceramics in actuator applications. In spite of these large strains in bismuth-based piezoelectric ceramics, there still remains a critical issue for its safe transfer to practical applications, representatively, a relatively high operating field required to obtain the large strain properties. To overcome the challenge, much attention has been paid to so-called 0-3(or 3-0) type ceramic/ceramic composite approach to better tailoring the strain properties of bismuth-based piezoelectric ceramics. The approach turns out to be highly effective, leading to a drastic decrease in the operating electric field for these materials. Besides, both extensive and intensive search for the related mechanism revealed that the reduction in the operating electric field is largely due to the contribution from polarization coupling or strain coupling model between two different ceramics. This article reviews the status of the art in the development of novel ceramic/ceramic composites to make large incipient piezostrains in bismuth-based lead-free piezoelectric ceramics practical.

• The Korean Journal of Ceramics
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• 제6권4호
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• pp.348-353
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• 2000

The effects of MnO$_2$ and Fe$_2$O$_3$ on the piezoelectric properties of 0.05PMN-0.451PT-0.499PZ ceramics were investigated. The addition of MnO$_2$ increased mechanical quality factor (Q$_m$) but decreased the dielectric constant (K$^{T}_{33}$) and compliance (S$^{E}_{11}$) of the specimens. These results indicated that MnO$_2$ behaves as an acceptor in 0.05MN-0.451PT-0.499PZ ceramics. The electromecanical coupling coefficient (K$_P$) of 0.05PMN-0.451PT-0.499PZ ceramics slightly increased with the addition of MnO$_2$ however, the enhancement of $K_P$ was insignificant. A small amount of Fe$_2$O$_3$ was added to enhance the $K_P$ of the 0.05PMN-0.451PT-0.499PZ + 0.5 wt% MnO$_2$ ceramics. The addition of Fe$_2$O$_3$ largely increased $K_P$ through the increase of the K$^{T}_{33}$ and the polarization. The mechanical quality factor of the specimens decreased with the addition of Fe$_2$O$_3$however, the reduction was negligible.

• 한국전기전자재료학회논문지
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• 제25권10호
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• pp.766-772
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• 2012

Spring supported piezoelectric cantilever structures (SPCS) were fabricated for vibration-based energy harvester application. We selected four elastic springs (A, B, C, and D type) as cantilever's supporter, each elastic spring has a different spring constant (S). The C type of SPCS ($S_C$: 4,649 N/m) showed a extremely low resonance frequency of 81 Hz along with the highest power output of 38.5 mW while the A type of SPCS ($S_A$: 40,629 N/m) didn't show a resonance frequency while. Therefore, it is considered that the lower spring constant lead to a lower resonance frequency of the SPCS. In addition, a tip mass (18 g) at one end of the SPCS could further reduce the resonance frequency without heavy degradation of power output.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.143-146
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• 2002

The characteristics of a multilayer piezoelectric transformer were investigated using 0.05Pb(A $l_{0.5}$N $b_{0.5}$) $O_3$-0.95Pb(Z $r_{0.52}$ $Ti_{0.48}$) $O_3$+0.9wt%N $b_2$ $O_{5}$+0.5wt%Mn $O_2$+0.04wt% $V_2$ $O_{5}$ ceramics. The multilayer piezoelectric trans formers were developed for voltage step-up. The multilayer ceramic technology was applied in piezoelectric transformer. The electrical characteristics of the piezoelectric transformer (33x8.5x1mm) has the efficiency of above 85%, step-up ratio of 70 under the 130 kΩ load, and driving frequency of 93.5kHz, respectively.ctively.y.y.

• 한국전기전자재료학회논문지
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• 제22권5호
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• pp.405-410
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• 2009

The conventional ultrasonic nozzle produces a mist by applying an ultrasonic vibration into a non-flowering liquid. In this paper, we first present a novel designed nozzle type sprayer that is able to apply an ultrasonic vibration directly to the moving liquid and generate a mist instantly. For the novel nozzle, a ring-type actuator of the novel nozzle was designed and built using the PZW-PMN-PZT ceramics. This paper will describe a variety of physical, mechanical, and electrical characteristics of the ultrasonic nozzle. The characteristics of the mist particles was also measured as the amount of the outflow liquid was varied.