• 한국세라믹학회지
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• 제33권11호
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• pp.1260-1266
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• 1996

The effects of SiO2 MnO2 and sintering atmospheres (O2, N2) on the piezoelectric properties and densification behaviors of Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 were investigated. The addition of SiO2 to the system enhanced the rate of densification but supressed the rate of grain growth. On the other hand the addition of MnO2 to the system did not nearly affect the rate of densification but increased slightly the rate of grain growth The densification of Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 containing of SiO2 or MnO2 was promoted with increasing the partial pressure of O2. The relative dielectric constant ($\varepsilon$r) and piezoelectric constant (d33) of Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 containing of SiO2 or MnO2 sintered under O2 atmosphere were higher than under N2 atmosphere. Whereas the mechanical quality factor (Qm) of specimens sintered under O2 atmosphere were lower than under N2 atmosphere. Thus the sintering atmosphere of O2 and N2 in Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 containing of SiO2 or MnO2 acted as donor and acceptor respectively. As the amount of SiO2 increased the relative dielectric constant ($\varepsilon$r) and piezoelectric constant (d33) of Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 but the mechanical quality factor (Qm) did not nearly change, In the case of the addition of MnO2 to the system the relative dielectric constant ($\varepsilon$r) and piezoelectric constant (d33) of Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 sintered under O2 atmosphere decreased rapidly with increasing the amount of MnO2 but they were unchanged with increasing the amount of MnO2 under N2 sintering atmosphere. Therefore the differences of the relative dielect-ric constant ($\varepsilon$r) and piezoelectric constant (d33) due to sintering atmosphere were diminished as the amount of MnO2 increased.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1258-1259
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• 2008

In this paper, the variable tendency of the piezoelectric constant and resonance characteristics of the piezoelectric ceramics due to the electric field is studied. The practical application of piezoelectric ceramics is not only applied in field of small signal. For example, in case of an ultrasonic motor, 120 ${\sim}$ 130Vrms of driving voltage is needed. Therefore, to examine the characteristics of piezoelectric ceramics in large signal contributes to reducing the susceptibility to the multifarious application and securing the ease of the production of control circuit. These contributions may be connected to the expansion of industrial application. We fabricated disk-type piezoelectric ceramic samples by using conventional method and measured the resonance characteristics of these samples under from low to high voltage driving conditions. According to increasing the value of the input voltage, we measured the resonance frequency of the piezoelectric ceramic, and inquired into the cause of these phenomena.

• Transactions on Electrical and Electronic Materials
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• 제10권4호
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• pp.121-124
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• 2009

In this study, in order to develop compositions of ceramics suitable for piezoelectric actuator and ultrasonic vibrator applications using low temperature sintering, multilayer, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3$ and $Na_2CO_3$ as sintering aids. Their structural, piezoelectric and dielectric characteristics were investigated according to the Zr/Ti ratio. As the Zr/Ti ratio increased, the electromechanical coupling factor $k_p$, and piezoelectric constant $d_{33}$ and the mechanical quality factor $Q_m$ all increased with Zr/Ti ratio and then decreased after the ratio exceeded 50/50. At the ratio of Zr/Ti =49/51 and sintering temperature of $900^{\circ}C$; the density, electromechanical coupling factor $k_p$, dielectric constant ${\varepsilon}_r$ piezoelectric $d_{33}$ constant and mechanical quality factor $Q_m$ all showed the optimum values of 7.900 $g/cm^3$, 0.576, 856, 312 pC/N, 1,326, respectively. These property values are very suitable for multilayer ceramics actuator applications.

• 한국전기전자재료학회논문지
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• 제14권1호
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• pp.20-25
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• 2001

To develop the piezoelectric actuator, the structural, dielectric and piezoelectric properties and electric fieldinduced strain of the ceramics(Pb$\_$1-2/Ba$\_$x/)[Mg$\_$1/2/W$\_$1/2/)$\_$0.03/-Ni$\_$1/3/Nb$\_$2/3/)$\_$0.12/-(Zr$\_$0.5/Ti$\_$0.5/)$\_$0.85/]O$_3$(x=0, 0.01, 0.03, 0.05, 0.07, 0.1) were investigated with the substitution of Ba. The tetragonality of crystal structure and grain size decreased by the substitution of Ba. Curie temperature decreased due to the decrease of the tetragonality, and dielectric constants increased with the substitution of Ba. The coercive field, remnant polarization and electromechanical coupling factor also decreased, whereas the piezoelectric constatns d$\_$33/ and d$\_$31/ were showed the highest value of 430 and 209(x10$\^$-12/C/N), respectively, because of the increase of dielectric constant. The strain induced by 60Hz AC electric field had the maximum value of 204x10$\^$-6/Δℓ/ℓ at the substitution of Ba 3mol%. As the applied electric field approaches to the coercive field, the piezoelectric element is depolarized and the electric field induced strain revealed non-linearity.

• 한국결정성장학회지
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• 제6권2호
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• pp.155-165
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• 1996

Growth of $LiNbO_3$ single crystal by Czochralski method was carried out to study the piezoelectric effects. Piezoelectric coefficients and elastic compliances of the $LiNbO_3$ single crystal were determined by the resonance method of length-extentional mode of bar resonator from the room temperature up to $100^{\circ}C$. Two dielectric constants of $LiNbO_3$ were also determined by measuring the capacitance of the plate specimen. Measured constants were piezoelectric coefficients $d_{15},d_{22},d_{31},d_{33}$ elastic compliances $s^E_{11},s^E_{33},2s^E_{13}+2s^E_{44},s^E_{14}$ and dielectric constants $K^T_{11},K^T_{33}$. As temperature increased, elastic compliances changed very slowly while piezoelectric coeffiecients and dielectric constant $K^T_{33}$ changed very rapidly. Electromechanical coupling constant of zyw ($45^{\circ}C$)-bar was as high as 0.51 in room temperature and nearly constant up to $1000^{\circ}C$. The increase of piezoelectric coefficients was mainly due to the increase of dielectric permittivity.

• 한국전기전자재료학회논문지
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• 제22권3호
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• pp.205-209
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• 2009

In this study, in order to develop the composition ceramics for lead-free ultrasonic motor, (1-x-0.09)$NaNbO_{3-x}BaTiO_3-0,09LiNbO_3$ ceramics were fabricated using a conventional mixed oxide process and their piezoelectric and dielectric characteristics were investigated according to the $BaTiO_3$ substitution. All the specimens showed orthorhombic phase structure without secondary phase, $BaTiO_3$ substitution enhanced density, dielectric constant(${\epsilon}_r$) and electromechanical coupling factor($k_p$), However, mechanical quality factor was deteriorated. Curie temperature of specimens was observed as about $380^{\circ}C$. At the $BaTiO_3$ substitution of 4 mol%, density, electromechanical coupling factor($k_p$), dielectric constant(${\epsilon}_r$) and piezoelectric constant($d_{33}$) of specimen showed the optimum value of $4.493g/cm^3$, 0.236, 175, 70 pC/N, respectively.

• 전기전자학회논문지
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• 제22권1호
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• pp.201-204
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• 2018

압전 상수 d의 값과 유전 상수 및 전기 기계적 결합 계수가 초음파 용접기에 사용되는 압전 세라믹의 출력에 영향을 주고 있습니다. 따라서 본 연구에서는 초음파 융착기의 진동 소자로 사용할 압전 세라믹 PZT-PMN-PZW의 $MnO_2$ 첨가량에 따른 세라믹의 특성을 조사 하였으며, $MnO_2$의 첨가량을 2 wt.%로 한 경우, 가장 우수한 특성을 얻을 수 있었으며, 이는 초음파 융착기용 진동소자로서의 적용 가능성을 시사하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1989년도 춘계학술대회 논문집
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• pp.63-65
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• 1989

Piezoelectric BaTiO$_3$-polymer composite were investigated for dielectric and piezoelectric properties with the barium titanate active particle size. Under the condition of the same density and ceramic volume ratio of composite, the dielectric and piezoelectric constant of composite are increasing as the ceramic particle size in composite are increasing. The surface layer model was quoted to explain these phenomena in our system and experimentally confirmed. The connectivity parameter of modified cube model of composite was calculated from the dielectric constant variation as their particle size. The connectivity parameter X and Y were 77.8% and 98.9% respectively. It means that the barium titanate particle distribution in composite nearly approach to the parallel mode. It was experimentally confirmed that the surface layer has low dielectric and nonferroelectric properties. Dielectric constant and thickness of surface layer were calculated from the equivalent circuit of composite.

• E2M - 전기 전자와 첨단 소재
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• 제1권1호
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• pp.44-53
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• 1988

In this study, PZT/PVDF composites with O-3 phase connectivity were prepared by hot pressing method, and the dielectric and piezoelectric properties as a function of PZT volume fraction were investigated. A modified cubic model was introduced to explain the influence of the PZT volume fraction on the experimentally determined dielectric constant. As A n=0.125, the measured dielectric constant values agreed with the calculated values. It was found that dielectric constant .xi.$_{33}$ and piezoelectric coefficient d$_{33}$ increased with indreasing PZT volume fraction, and hydrostatic piezoelectric figure of merit d/aub h/.g$_{h}$ was improved relative to that of the PZT single phase material.l.l.l.

• 한국재료학회지
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• 제25권10호
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• pp.523-530
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• 2015

Electricity generation through fossil fuels has caused environmental pollution. To solve this problem, research on new renewable energy (solar, wind, geothermal heat, etc.) to replace fossil fuels is in progress. These devices are able to consistently generate power. However, they have many drawbacks, such as high installation costs and limitations in possible set-up environments. Thus, piezoelectric harvesting technology, which is able to overcome the limitations of existing energy technologies, is actively being studied. Piezoelectric harvesting technology uses the piezoelectric effect which occurs in crystals that generate voltage when stress is applied. Therefore, it has advantages such as a wider installation base and lower technological cost. In this study, a piezoelectric energy harvesting device based on constant wave motion was investigated. This device can regenerate electricity in a constant turbulent flow in the middle of the sea. The components of the device are circuitry, a steel bar, an bimorph piezoelectric element and buoyancy elements. In addition, a multiphysical analysis coupled with the structure and piezoelectric elements was conducted to estimate the performance of the device. With this piezoelectric energy harvesting device, the displacement and electric power were analyzed.