• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.149-152
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• 2001

A great deal of attention has been focused on the application of miniaturized piezoelectric transformers to the low power source for the microsystem. The dielectric and piezoelectric properties of Pb(Mn,W,Sb,Nb)O$_3$-Pb(Zr,Ti)O$_3$ ceramics have been investigated on different calcination(750$^{\circ}C$∼950$^{\circ}C$) and sintering(1100$^{\circ}C$∼1300$^{\circ}C$) temperatures. The perovskitic phase was formed by the solid phase reaction of the oxides. Anisotropic (k$\sub$t/k$\sub$p/) properties of electromechanical coupling coefficient and piezoelectric coefficient have been proven to be depending on processing temperatures. The value of electromechanical coupling factor of K$\sub$p/>0.51 and a mechanical quality factor of Q$\sub$m/>2000 were obtained. The piezoelectric transformer was prepared using this ceramics with the composition of Pb(Mn,W,Sb,Nb)O$_3$-Pb(Zr,Ti)O$_3$ We studied the influence of different processing temperature on the microstructure and piezoelectric properties of complex PZT-based ceramics. and the characteristic of piezoelectric transformer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.6
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• pp.455-459
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• 2001

In this paper, the dielectric and pizoelectric properties of 0.05Pb(M $n_{04}$ $W_{0.2}$N $b_{0.4}$) $O_3$-0.95(PbZ $r_{x}$ $Ti_{1-x}$ ) $O_3$+yN $b_2$ $O_{5}$ , are investigated as a function of the mole ratio of Zr and the amount of N $b_2$ $O_{5}$ . Also, the phase is analyzed by XRD. When the mole ratio of Zr is 0.51, the electromechanical coupling coefficient( $k_{p}$ ), relative dielectric constant ($\varepsilon$$^{T}$ $_{33}$ /$\varepsilon$$_{0}$ ), piezoelectric stain constrain ( $d_{33}$ and dielectric loss tangent show maximum, while the mechanical quality factor shows minimum value ; $k_{p}$ =56.5%, $d_{33}$ =258pC/N, $\varepsilon$$^{T}$ $_{33}$ /$\varepsilon$$_{0}$ =1170, $Q_{m}$ =1150, tan$\delta$=0.51%. At that composition, MPB which rhombohedral and tetragonal phase coexist in this ternary system is shown by the results of XRD analysis. Also, when the amount of N $b_2$ $O_{5}$ is 0.3wt%, the mechanical quality factor is increased to about 2000. The phase transition temperature of the ternary piezoelectric ceramic system showed about 35$0^{\circ}C$.TEX>.>.>.

• 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.

• Transactions on Electrical and Electronic Materials
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• v.15 no.4
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• pp.226-229
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• 2014

In this study, lead-free $(Ba_{0.85}Ca_{0.15})(Ti_{1-x}Zr_x)O_3$ ceramics and a bimorph-type piezoelectric actuator were fabricated using the normal oxide-mixed sintering method, and their dielectric properties, microstructure, and displacement properties were investigated. From the results of X-ray diffraction, the pattern of the specimen has a pure perovskite structure. In addition, no secondary impurity phases were found. The excellent piezoelectric coefficient of $d_{33}=454pC/N$, the electromechanical coupling factor $k_p=0.51$, the dielectric constant ${\varepsilon}_r=3,657$, the mechanical quality factor $Q_m=239$, and $T_c$(Tetragonal-Cubic) =$90^{\circ}C$ were shown at x= 0.085. ${\Delta}k_p/k_p20^{\circ}C$ and ${\Delta}f_r/f_r20^{\circ}C$ showed the maximum value of -0.255 and 0.111 at $-20^{\circ}C$ and $80^{\circ}C$, respectively. The maximum total-displacement was $60{\mu}m$ under the input voltage of 50 V. As a result, it is considered that lead-free $(Ba_{0.85}Ca_{0.15})(Ti_{1-x}Zr_x)O_3$ ceramics is a promising candidate for piezoelectric actuator application for x= 0.085.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.403-406
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• 2000

The piezoelectric properties and the doping effect of N $b_2$ $O_{5}$ and Mn $O_2$for 0.95PbZ $r_{x}$ $Ti_{x}$ $O_3$+0.05Pb(M $n_{0.42}$ $W_{0.26}$S $b_{0.32}$) $O_3$ compositions have been investigated. In the composition of 0.95PbZ $r_{0.54}$ $Ti_{0.46}$ $O_3$+0.05Pb(M $n_{0.42}$ $W_{0.26}$S $b_{0.32}$) $O_3$the Values Of $k_{p}$ find and $\varepsilon$$_{33}$ $^{T}$ are maximized, but $Q_{m}$ Was minimized ( $k_{p}$ =0.51, $Q_{m}$ =1750). The grain size was suppressed and the uniformity of grain was improved with doping concentration of N $b_2$ $O_{5}$ for 0.95PbZ $r_{0.54}$ $Ti_{0.46}$ $O_3$+0.005Pb(M $n_{0.42}$ $W_{0.26}$S $b_{0.32}$) $O_3$sample. The values of $k_{p}$ increased and the values of $Q_{m}$ slightly decreased when 0.5 wt% of N $b_2$ $O_{5}$ is doped. And the values of $k_{p}$ was the same formation of the N $b_2$ $O_{5}$ dopant when 0.5 wt% of M $n_2$ $O_{5}$ is doped. But the values of $Q_{m}$ was deeply decreased when 0.5 wt% of Mn $O_2$is doped. As a experiment results under high electric field driving, this piezoelectric ceramics are very stable. Conclusively, piezoelectric ceramic compsiton investigated at this paper is suitable for application to high power piezoelectric devices.. devices..ices.. devices..

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.60-63
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• 1997

Dieletric ailed piezoelectric properties of Pb[$Zr_{0.45}$/ $Ti_{0.5-x}$/L $u_{x}$ (M $n_{1}$3//S $b_{2}$3)$_{0.05}$] $O_3$(0$\leq$x $\leq$0.03) were investigated. The partial substitution of $Ti^{4+}$ by a L $u^{3+}$ permitted improvement of the piezoelectric constant( $d_{33}$ ), electromechanical coupling factor ( $k_{p}$ ) and dielectric constant($\varepsilon$$_{33}$ /Sup T/). The dielectric loss(tan $\delta$ ) increased and mechanical quality factor(Qm) decreased with an increase of x were observed. A new piezoelectric material for actuator application was developed at x=0.02 with $d_{33}$ =370$\times$10$^{-2}$ /C/N, $k_{p}$ =58.5%, $\varepsilon$$_{33}$ $^{T}$ =1321, $Q_{m}$ =714 and tan $\delta$ =0.98%.%..%.%.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.33.2-33.2
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• 2009

Dielectric and piezoelectric properties of Lead-free $(1-x)(Bi_{0.5}K_{0.5})TiO_3-xBiFeO_3$ceramics prepared by a conventional solid state reaction method were investigated in the range of x = 0~10 mol%. Piezoelectric coefficient was increased from 31 pC/N at x = 0 mol% to 64 pC/N at x = 6 mol% then decreased with increasing x. Electromechanical coupling factor ($K_p$) was increased up to 0.18 at x = 10 mol%. On the other hand, mechanical quality factor ($Q_m$) was decreased. Grain size was not much changed with various x and a single perovskite with tetragonal symmetry was maintained at all compositions forming a solid solution between $(Bi_{0.5}K_{0.5})TiO_3$ and $BiFeO_3$. Depolarization temperature ($T_d$) was gradually decreased with increasing x from $302^{\circ}C$ at x = 0 to $245^{\circ}C$ at x = 10 mol%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.5
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• pp.475-479
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• 1999

Langasite ($La_{3}Ga_{5}SiO_{14}$) was found to have wide application as a promising piezoelectric material. It has high thermal stability of the frequency and large electromechanical coupling factor. For the further development of new compounds with langasite type structure, powders in the La-Al-Si-O system were synthesized by a modified Pechini process. The evolution of the crystalline phase during calcination was studied using TG-DTA, XRD and TEM for the precursor powders. Decomposition proceeded via dehydration and removal of excess solvents at low temperatures ($T<500^{\circ}C$), followed by the crystallization of lanthanum aluminum silicate ($T>800^{\circ}C$) and phase transformation to $LaAlO_{3}$ phase ($T>1200^{\circ}C$). Transmission electron microscopy (TEM) of the calcined powders showed diffuse hollow rings corresponding to an amorphous phase at $800^{\circ}C$ and clear diffraction patterns corresponding to a crystalline phase from the P321 space group ($T<1200^{\circ}C$) and the R3m ($T<1200^{\circ}C$).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.297-299
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• 1999

Effects of additives on the ceramic and electrical properties of Pb(Y$_{1}$2/Ta$_{1}$2/)O$_3$-PbZrO$_3$-PbTiO$_3$ceramics in a perovskite type structure were investigated. The dielectric and piezoelectric properties of the base composition were improved markedly through selection of Fe$_2$O$_3$ additives in proper amounts. The composition Pb(Y$_{1}$2/Ta$_{1}$2/)O$_3$-PbZrO$_3$-PbTiO$_3$ obtained the dielectric constant ($\varepsilon$$_{r}$=1,425). Also, electromechanical couping factors for planar(k$_{p}$) and piezoelectric constant(d$_{33}$) were obtained 0.50 and 294[pC/N] at the additives 0wt% Fe$_2$O$_3$ respectively. The mechanical quality facor(Q$_{m}$) of Pb(Y$_{1}$2/Ta$_{1}$2/)O$_3$-PbZrO$_3$-PbTiO$_3$+Fe$_2$O$_3$(0.3 wt%) is about 510.510.510.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.11
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• pp.806-809
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• 2013

In this study, $(Na_{0.525}K_{0.443}Li_{0.037})(Nb_{0.883}Sb_{0.08}Ta_{0.037})O_3+0.10\;wt%Bi_2O_3+0.35\;wt%B_2O_3$ ceramics were prepared by conventional soild-state sintering process. The specimens were sintered at temperature range from $1,060^{\circ}C$ to $1,100^{\circ}C$. XRD (X-ray diffractron), SEM (scanning electron microscope) were used to analyze the crystal structure and microstructural sproperties of specimens. And also, $T_{O-T}$, TC were observed by the mesurement of temperature dependence of dielectric constant. Excellect physical properties of the piezoelectric constant $d_{33}$= 170 pC/N, electromechanical coupling factor kp= 0.312, Tc= $315^{\circ}C$ were obtained, respectively, from the specimen sintered at $1,080^{\circ}C$.