• 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 Institute of Electrical and Electronic Material Engineers
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• v.24 no.9
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• pp.728-732
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• 2011

In this study, piezoelectric and dielectric properties of Lead-free $0.97[(K_{0.5}Na_{0.5})(Nb_{0.97}Sb_{0.03})O_3]+0.03[(Bi_{0.5}K_{0.5})TiO_3]$ (abbreviated as 0.97NKNS-0.03BKT)ceramics synthesized by conventional solid-state reaction process were investigated as a function of $K_{5.4}Cu_{1.3}Ta_{10}O_{29}$ addition. The results indicated that the $K_{5.4}Cu_{1.3}Ta_{10}O_{29}$ addition significantly improved the sinterability, grain growth and piezoelctric properties of 0.97NKNS-0.03BKT ceramics. The optimum values as planar piezoelectric coupling coefficient ($k_p$= 0.355), piezoelectric constant ($d_{33}$= 207 pC/N) and mechanical quality factor ($Q_m$= 128) were obtained when 0.009KCT was added. The electromechanical coupling factor($k_p$) was slightly decreased according to the increasing temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.256-256
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• 2007

As a candidate for lead-free piezoelectric materials, dense ($(Na_{0.47}K_{0.47}Li_{0.06})NbO_3$ (LNKN6) ceramics were developed by conventional sintering process. Sintering temperature was lowered by adding $Li_2O$ as a sintering aid. Abnormal grain growth in the LNKN6 ceramics was observed with varying $Li_2O$ content. The electrical properties of LNKN6 ceramics were investigated as a function of $Li_2O$ concentration. When the sample sintered at $1000^{\circ}C$ for 4h with the addition of 1 mol% $Li_2O$, electromechanical coupling factor ($k_p$) and piezoelectric coefficient ($d_{33}$) of LNKN6 ceramics were found to reach the highest values of 0.40 and 184 pC/N, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.315-316
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• 2006

Dense $0.95(Na_{0.5}K_{0.5})NbO_3-0.05LiTaO_3$ (NKN-LT) ceramics were developed by conventional sintering process. Sintering temperature was lowered by adding $Na_2O$ as a sintering aid. The electrical properties of NKN-LT ceramics were investigated as a function of $Na_2O$ concentration. When the sample sintered at $1000^{\circ}C$ for 4h with the addition of 1 mol% $Na_2O$, electromechanical coupling factor ($k_p$) and piezoelectric coefficient ($d_{33}$) of NKN-LT ceramics were found to reach the highest values of 0.43 and 190 pC/N, respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.694-695
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• 2006

As a candidate for lead-free piezoelectric materials, dense $95(Na_{0.5}K_{0.5})NbO_3-5LiTaO_3$ (NKN-5LT) ceramics were developed by conventional sintering process. Sintering temperature was lowered by adding $Li_2O$ as a sintering aid. The electrical properties of NKN-5LT ceramics were investigated as a function of $Li_2O$ concentration. At the addition of 1 mol% $Li_2O$, electromechanical coupling factor $(k_P)$ and piezoelectric coefficient $(d_{33})$ of NKN-5LT ceramics were found to reach the highest values of 0.37 and 250 pC/N, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.466-469
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• 2016

In this study, in order to develop composition ceramics for Acoustic Emission (abbreviated as AE) sensor application, the PZT system ceramics was fabricated by conventional solid state reaction method. When x=0.48, the density, electromechanical coupling factor($k_p$), piezoelectric coefficient $d_{33}$ and piezoelectric voltage constant $g_{33}$ of the maximum values of $7.857g/cm^3$, 0.51, 190[pC/N], 52[$10^{-3}mV/N$] were obtained, respectively, suitable for AE sensor.

• Transactions on Electrical and Electronic Materials
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• v.5 no.2
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• pp.76-80
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• 2004

Piezoelectric and dielectric properties as functions of x and y mole ratio in yPb(ZrxTil-x)O$_3$(1-y)Pb(Mn$\_$1/3/Nb/2/3/)O$_3$, ceramics, PZT-PMN, are investigated for large displacement piezoelectric devices. From the experimental results, when y is 0.95 and x is 0.505, the piezoelectric and dielectric properties are maximum, that is, electromechanical coupling coefficient(kp), piezoelectric strain constant(d$\_$33/), permittivity($\varepsilon$$\_$33/$\^$T//$\varepsilon$$\_$0/), and Curie temperature are 58 %, 272 pC/N, 1520 and about 350$^{\circ}C$, respectively. Also, when y is 0.90 and x is 0.50, their properties are 56 %, 242 pC/N, 1220, and 290$^{\circ}C$, respectively. As MgO dopant is added from 0 wt% to 1 wt%, kp increases to 63 % and Qm decreases to 500 at the MgO dopant of 0.1 wt%, and then kp decreases to 57 % as MgO is added.

• 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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• 2001.11a
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• pp.100-102
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• 2001

In this paper, the piezoelectric and dielectric properties of $Pb(Zr_xTi_{1-x)O_3$ - $Pb(Co_{1/3}Nb_{1/3})O_3)$ piezoelectric ceramics have been investigated as a function of Zr/Ti mole ratio. From the results, when Zr/Ti mole ratio is 49/51, electromechanical coupling coefficient($k_p$), piezoelectric strain constant($d_{33}$) mechanical quality factor($Q_m$), and Permittivity(${{\varepsilon}_{33}}^T/{\varepsilon}_0$) is 64[%], 469[PC/N], 360 and 2000, respectively. Morphotropic Phase Boundary is Zr/Ti mole ratio(49/51) from XRD analysis. Also. From SEM observation, when sintering temperature is 1150[$^{\circ}C$], grain size is about $1{\sim}2[{\mu}m]$ and maximum sintering density is 7.85[$g/cm^3$].

• Electrical & Electronic Materials
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• v.10 no.9
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• pp.909-915
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• 1997

To improve the electro-induced strain and to decease the hysteresis of that W $O_3$dopant of which amount is 0~0.8wt% was added to (P $b_{0.73}$/B $a_{0.27}$)(Z $r_{0.75}$/ $Ti_{0.25}$) $O_3$+0.1wt% $Y_{2}$/ $O_3$ceramics. At the specimen with 0.4 wt% W $O_3$the electromechanical coupling coefficient( $K_{31}$ ) showed the maximum value of 23.6% at D.C 10 kV/cm electric field. At the same W $O_3$addition amount the piezoelectric constant( $d_{31}$ ) and the electro-induced strain($\Delta$$\ell$/$\ell$)showed the highest values of 182$\times$10$^{-12}$ [C/N] 210$\times$10$^{-6}$ $\Delta$$\ell$/$\ell$at D.C. 10 kV/cm electric field. respectively0 kV/cm electric field. respectivelyvely.