• Transactions on Electrical and Electronic Materials
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• v.4 no.2
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• pp.20-23
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• 2003

Piezoelectric powder with the composition of PbTiO$_3$-PbZrO$_3$-Pb(Mn$\_$1/3/Nb$\_$2/3/)O$_3$ and small particle size of 0.3 $\mu\textrm{m}$ was investigated for low-temperature firing of PZT thick films. PbTiO$_3$-PbZrO$_3$-Pb(Mn$\_$1/3/Nb$\_$2/3)O$_3$ ceramics showed dense microstructure and superior piezoelectric properties, electromechanical coupling factor (k$\_$p/) of 0.501 and piezoelectric constant (d$\_$33/) of 224. The PZT paste was made of the powder and organic vehicles, and screen-printed on Pt(450nm)/YSZ(110nm)/SiO$_2$(300nm)/Si substrates and fired at 800∼900$^{\circ}C$. Any interface reaction between the PZT thick film and the bottom electrode was not observed in the PZT thick films. The PZT thick film fired at 800$^{\circ}C$ showed moderate electrical properties, the remanent polarization(p$\_$r/) of 16.0 ${\mu}$C/$\textrm{cm}^2$, the coercive field(E$\_$c/) of 36.7 ㎸/cm, and dielectric constant ($\varepsilon$$\_$r/) of 531. Low-temperature sinterable piezoelectric composition and high activity of fine particles reduced the sintering temperature of the thick film. This PZT thick film could be utilized for piezoelectric microactuators or microsensors that require Si micromachining technology.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.204-208
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• 2013

In this study, $KNbO_3$-substituted (Li,Na,K)(Nb,Sb,Ta)$O_3$ ceramics were investigated to develop Pb-free composition ceramics for multilayer actuator and energy harvester applications. The X-ray diffraction analysis indicated that all samples were pure perovskite phase and no secondary phase was found. A tetragonality as a function of $KNbO_3$ substitution showed the maximum value at 1.5 mol% $KNbO_3$ and then decreased. The SEM image analysis showed the maximum grain size of $3.14{\mu}m$ at 1.5mol% $KNbO_3$. In the composition ceramics with 1.5 mol% $KNbO_3$ sintered at $1,100^{\circ}C$, excellent properties of density= 4.75 $g/cm^3$, electromechanical coupling factor ($k_p$)= 0.50 and piezoelectric constant($d_{33}$)= 290 pC/N were obtained, respectively, suitable for piezoelectric actuator and energy harvester applications.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.10
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• pp.458-463
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• 2003

In order to develope piezoelectric transformer for the ballast of fluorescent lamp, a new shape and electrode pattern of piezoelectric transformer has been investigated in this work. The composition of piezoelectric ceramics was 0.95Pb(Zr$_{0.51}$Ti$_{0.49}$)O$_3$+0.03Pb(Mn$_{1}$3/Nb$_{2}$3/)O$_3$+0.02Pb(Sb$_{1}$2/Nb$_{1}$2/)O$_3$. The sample prepared by this composition system showed the characteristics which has about 1200 of relative dielecric constant, 1100 of the mechanical quality factor, 0.53 of the electromechanical coupling coefficient, 320 pC/N of the piezoelectric constant d$_{33}$, 0.3 % of the dissipation factor. Diameter and thickness of disk-type piezoelectric transformer was 45 mm and 4 mm, respectively. The driving and generating electrode with their gap of 1mm were fabricated on the top surface. But the common electrode was fabricated on the whole bottom surface. The electrode surface ratio of driving and generating part on the top surface ranges from 1.4:1 to 3:1. We investigated the electrical characteristics with the variation of the electrode surface ratio of driving and generating part in the range of load resistance of 100 $\Omega$～70 k$\Omega$. The set-up voltage ratio of this piezoelectric transformer increases with increasing both the electrode surface of driving part and the load resistance. The set-up voltage ratio at no load resistance was more than 60 times. On the other hand, the efficiency decreases with increasing the electrode surface of driving part. In the case of the electrode surface of both 1.4:1 and 2:1, maximum efficiency showed above 97 % at load resistance of 2 k$\Omega$. However, in the case of the electrode surface of 3:1, maximum efficiency showed about 94 % at load resistance of 3 k$\Omega$.>.>.>.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.9
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• pp.766-771
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• 2009

Lead-free $0.94(Na_{0.5}K_{0.5})NbO_3$-0.06Ba$(Ti_{0.9}Sn_{0.1})O_3$ [0.94NKN-0.06BTS] ceramics doped with 1 mol% $MnO_2$ were synthesized by a conventional solid state method. The phase transitional behavior and piezoelectric properties of the ceramics sintered at various temperatures were investigated. The 0.94NKN-0.06BTS ceramics sintered at $1050^{\circ}C$, having morphotropic phase boundary of orthorhombic and tetragonal phases, exhibited a microstructure with abnormal grain growth. A diffused phase transition behavior for all the specimens was verified as high degree of diffuseness (${\gamma}$) values from 1.45 to 1.79. A high piezoelectric constant of $d_{33}=256$ pC/N and a satisfactory electromechanical coupling factor of $k_p=42%$ were obtained for the relatively dense 0.94NKN-0.06BTS ceramics sintered at $1050^{\circ}C$.

• The Journal of the Acoustical Society of Korea
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• v.23 no.2
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• pp.103-108
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• 2004

In this paper, all the materials constants of the PMN-32%PT single crystals grown by the solid state crystal growth method were measured by the resonance method. PMN-PT crystals of tetragonal symmetry have six elastic constants, three piezoelectric constants and two dielectric constants for their independent material constants. These materials constants were extracted from six sets of crystal samples of each different geometry to have different vibration modes respectively. Measured results showed that the crystal has larger electromechanical coupling factor k/sub 33/ (∼86%) and piezoelectric constant d/sub 33/ (∼1200pC/N) than conventional piezoceramics. Validity of the measurement was confirmed through comparison of the results with the impedance spectrum from finite element analysis of the samples and the results measured with a commercial do meter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1320-1325
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• 2004

In this study, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, PCW-PMN-PZT ceramics added with Li$_2$CO$_3$, Bi$_2$O$_3$ and CuO as sintering aids were manufactured, and their microstructural, dielectric and piezoelectric properties were investigated. When the only CuO was added, specimens could not be sintered below 98$0^{\circ}C$. However, when Li$_2$CO$_3$ and Bi$_2$O$_3$ were added, specimens could be sintered below 98$0^{\circ}C$. Li$_2$CO$_3$ and Bi$_2$O$_3$ addition were proved to lower sintering temperature of piezoelectric ceramics due to the effect of Li$_2$O-Bi$_2$O$_3$ liquid phase. Li$_2$CO$_3$ and Bi$_2$O$_3$ added specimens showed higher piezoelectric properties than those of the only CuO added specimens. At 0.2 wt% Li$_2$CO$_3$ and 0.3 wt% Bi$_2$O$_3$ added specimen sintered at 92$0^{\circ}C$, the dielectric constant of 1457, electromechanical coupling factor of 0.56 and mechanical quality factor of 1000 were shown, respectively. These values are suitable for multilayer piezoelectric transformer application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1174-1177
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• 2004

The dielectric and piezoelectric properties of silver added 0.96 Pb(Z $r_{0.52}$ $Ti_{0.48}$) $O_3$-0.04 Pb(Mn,W,Sb,Nb)$_3$ ceramics were examined. By varying the contents of silver(0.0, 0.4, 1.0 mol%), the effect of silver addition on PZT-PMWSN ceramics was investigated at various sintering temperature(900, 1000, 1100 $^{\circ}C$). As increasing silver contents, the relative dielectric constant was increased and sinterability was enhanced. At the specimen with 0.4 mol% Ag and sintered at 1000 $^{\circ}C$, electromechanical coupling factor( $k_{p}$), mechanical quality factor( $Q_{m}$), dielectric constant($\varepsilon$$_{r}$) and dielectric loss were 0.502, 811, 991, 0.006, respectively. The results showed that the PZT-PMWSN/Ag composites have enhanced piezoelectic and dielectric properties and sintering temperature was lowered.red.

• Journal of the Korean Ceramic Society
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• v.41 no.9
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• pp.709-714
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• 2004

The additive of low temperature sintering in Mn-doped PMN-PZT known as high piezoelectric materials was studied in this experiment. B$_2$O$_3$ was used for the additive of low temperature sintering. The effects of sintering temperature in dielectric, and piezoelectric properties were investigated with the amounts of B$_2$O$_3$. Sintered density was increased in comparison with no addition and under 2wt％ B$_2$O$_3$ and lower sintering temperature than 100$0^{\circ}C$. Therefore, in the low sintering temperature, the densification was improved by the addition of the B$_2$O$_3$. However, the sintering density was lower than that of the main composition in the case of the sintered at over 10$50^{\circ}C$. Dielectric constant with the addition of B$_2$O$_3$ was evaluated. The dielectric constant was 1000 2 wt％ of B$_2$O$_3$ and sintered at 100$0^{\circ}C$. Under 2wt％ of B$_2$O$_3$, the electromechanical coupling factor and the piezoelectric constant were not so much decreased. The electromechanical coupling factor and the piezoelectric constant were 50％ and 300(${\times}$10$^{-12}$ C/N) respectively. The mechanical quality factor was increased with B$_2$O$_3$. The mechanical quality factor was 1700 at 0.5wt％ B$_2$O$_3$ and sintered at 110$0^{\circ}C$. Dielectric loss was less than 0.5％ regardless of the amount of B$_2$O$_3$.

• Korean Journal of Materials Research
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• v.15 no.10
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• pp.639-643
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• 2005

Lead-free $[Bi_{0.5}(Na_{1-x}K_x)_{0.5}TiO_3](x=0\~1.0)$ ceramics were prepared using a solid state reaction method and their structural and electrical characteristics were investigated. X-ray investigations indicated that the rhombohedral-tetragonal morphotropic phase boundary(MPB) of the $[Bi_{0.5}(Na_{1-x}K_x)TiO_3$ ceramics exists in the range of $x=0.16\~0.20$. The optimum values of piezoelectric constant$(d_{33})$, dielectric constant, and electromechanical coupling factor $(k_p)$ were obtained at $x=0.16\~0.20$ of the MPB region.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.5
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• pp.517-524
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• 1992

In this study, 0.10Pb(SbS11/2TSnS11/2T)OS13T-(0.90-x)PbZrOS13T (0.25 x 0.40) ceramics were fabricated by the atmospheric method. The sintering temperature and time were 1250[$^{\circ}C$] and 2[2hr], respectively. The structureal, dielectric and piezoelectric properties with composition of PbTiOS13T were studied. As the results of XRD ans SEM, the crystal structure of a specimen was rhombohedral, lattice constant and average grain size were decreased with increasing the contents of PbTiOS13T. Relative dielectric constant and Curie temperature were increased with increasing the contents of PbTiOS13T, 0.10PSS-0.40PT-0.50PZ specimen had the highest values of 904 and 265[$^{\circ}C$], respectively. In increasing of PbTiOS13T contents form 25[mol%] to 40[mol%], piezoelectric charge constant and electromechanical coupling factors were increased form 114[pC/N] to 142[pC/N], 17[%] to 24[%] and mechanical quality factor were decreased with increasing the contents of PbTiOS13T. In the 0.10PSS-0.40PT-0.50PZ specimens, those values were 14.2[kV/cm] and 9.43[x10S0-6TC/cmS02T], resectively.