• 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.32 no.5
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• pp.418-425
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• 2019

A piezoelectric ceramic fiber composite (PCFC) was successfully fabricated using $0.69Pb(Zr_{0.47}Ti_{0.53})O_3-0.31[Pb(Zn_{0.4}Ni_{0.6})_{1/3}Nb_{2/3}]O_3$ (PZT-PZNN) for use in small-scale wind energy harvesters. The PCFC was formed using an epoxy matrix material and an array of Ag/Pd-coated PZT-PZNN piezo-ceramic fibers sandwiched by Cu interdigitated electrode patterned polyethylene terephthalate film. The energy harvesting performance was evaluated in a custom-made wind tunnel while varying the wind speed and resistive load with two types of flutter wind energy harvesters. One had a five-PCFC array vertically clamped with a supporting acrylic rod while the other used the same structure but with a five-PCFC cantilever array. Stainless steel (thickness: $50{\mu}m$) was attached onto one side of the PCFC to form the PZT-PZNN cantilever. The output power, in general, increased with an increase in the wind speed from 2 m/s to 10 m/s for both energy harvesters. The highest output power of $15.1{\mu}W$ at $14k{\Omega}$ was obtained at a wind speed of 10 m/s for the flutter wind energy harvester with the PZT-PZNN cantilever array. The results presented here reveal the strong potential for wind energy harvester applications to supply sustainable power to various IoT micro-devices.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1213-1217
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• 2008

Poling is an important process in fabricating PZT ceramic devices such as filters and resonators and activates piezoelectricity to sintered PZT ceramics. Tolerance of the operating frequency of these devices is tightly required in applications. And a factor to attribute the tolerance is the temperature dependence of the resonance frequency of PZT ceramics. In this paper the relationship of poling strength and temperature dependence of resonance frequency of PZT specimens was studied. The $Pb(Zr_{0.53}Ti_{0.47})O_3$ ceramics were fabricated and the poling strengths were chosen to be 0.5, 1.5, 2.5 and 3.5 [kV/mm]. The dielectric constant of the specimen poled in poling strength 0.5 [kV/mm] was less than that of unpoled specimen and the specimen poled in higher electric field had the higher dielectric constant. (002) peak in X-ray diffraction patterns of the specimens increased as poling strength increased. And the change of resonance frequency of the specimens according to the variation of temperature was measured. Resonance frequency of all specimens increased as the temperature increased. The specimen poled in higher electric field had the smaller positive temperature coefficient of resonance frequency. The effect that temperature coefficient of resonance frequency becomes smaller is obtained when Zr mole in PZT composition equation increase. Controlling the poling strength is believed to be a method to adjust the temperature stability of resonance frequency of the PZT ceramic devices.