• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.188-189
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• 2009

In this study, in order to develop excellent lead-free composition ceramics for piezoelectric transformer, $(K_4CuNb_8O_{23})$ added $(K_{0.5}Na_{0.5})(Nb_{0.96}Sb_{0.04})O_3$ ceramics were fabricated using conventional mixed oxide method and their piezoelectric and dielectric properties were investigated as a function of the amount of KCN addition. With increasing the amount of KCN addition, density and mechanical quality factor(Qm), electromechanical coupling factor (Kp) were increased up to 1.2mol% and then decreased. At the 1.2mol% KCN added specimen, mechanical quality factor (Qm), electromechanical coupling factor (Kp), density and dielectric constant (${\varepsilon}r$) showed the optimal values of 781, 0.445, $4.42g/cm^3$ and 443, respectively, for piezoelectric transformer application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.8
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• pp.671-677
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• 2002

In this study, the high frequency SMD ceramic resonators with the size of $3.7{\times}3.1{\times}0.385\textrm{mm}^3$ were fabricated using $Pb_{0.88}(La_{0.6}Nd_{0.4})_{0.08}(Mn_{1/3}Sb_{2/3})_{0.02}Ti_{0.98}O_3$ ceramics with the variations of electrode radius size. With increasing the electrode radius size, resonant resistance in third overtone mode was decreased and electromechanical coupling factor($k_{t3}$) in third overtone mode was showed constant values. Taking into consideration mechanical quality factor($Qm_{t3}$) of 5,552 and dynamic range(D.R) of 60.72dB in third overtone mode, the ceramic resonator with the electrode radius size of $\theta$1.13mm was suitable for 20MHz resonator application.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.260-264
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• 1999

In this paper, the structural, dielectrial and piezoelectrical properties of 0.03Pb(Sb$\sub$1/2/Ti$\sub$0.495/)O$_3$+Xwt% MnO(x= 0, 0.3, 0.4, 0.5, 0.7) system ceramics were investigated as a function of the addition of MnO. As a result, the samples of 0.3wt% MnO content showed the highest mechanical quality factor(Qm) of 1487, and its dielectric constant and electro mechanical coupling factor(Kp) 1357, 54.3%, respectively. Therefore, the dielectrial and piezoelectrical properties of the composition ceramics were indicated as the materials suitable for piezoelectric transformer.

• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.378-384
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• 1995

Effects of $La_2O_3$, $MnO_2$ on the dielectric and piezoelectric properties of $0.02Pb(Y_{2/3}W_{1/3}O_3-0.98Pb(Zr_{0.52}Ti_{0.48})O_3$ system were investigated. The addition of La2O3 to the system enhanced electromechanical coupling factor (kp), piezoelectric constant (d33), but hardly changed mechanical quality factor (Qm). On the other hand, the addition of $MnO_2$ increased Qm significantly, but did not degrade kp and d33 so much. The piezoelectric properties of $0.02Pb(Y_{2/3}W_{1/3}O_3-0.98Pb(Zr_{0.52}Ti_{0.48})O_3$ containing 0.1wt% $La_2O_3$, 0.4wt% $MnO_2$ were very good and kp, d33, Qm were 55%, 350$\times$10-12C/N, 780, respectively. The size of the grains was proportional to the change of c/a (tetragonality) ratio caused by the addition of $La_2O_3$ and $MnO_2$, and dielectric, piezoelectric properties were sensitive to the amountof pyrochrole phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.53-53
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• 2008

Piezoelectric transformers have been widely used such as DC-DC convertor, invertor, Ballast, etc. Because, the y have some merits compared with electro-magnetic transformers such as step-up ratio, high efficiency, small size and lg hit weight, etc. Piezoelectric transformer require high electromechanical coupling factor kp in order to induce a large out put power in proportional to applied electric field. And also, high mechanical quality factor Qm is required to prevent mechanical loss and heat generation. In general, PZT system ceramics should be sintered at high temperatures between 1200 and $1300^{\circ}C$ in order to obtain complete densification. Accordingly, environmental pollution due to its PbO evaporation. Hence, to reduce its sintering temperature, various kinds of material processing methods such as hot pressing, high energy mill, liquid phase sintering, and using ultra fine powder have been performed. Among these methods, liquid phase sintering is basically an effective method for aiding densification at low temperature. In this study, In order to comparis on low temperature sintering and solid state sintering piezoelectric transformers, rosen type transformers were fabricated u sing two PZT ceramics compositions and their electrical properties were investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.11
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• pp.930-934
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• 2009

In this study, in order to develop excellent lead-free composition ceramics for piezoelectric transformer, ($K_4CuNb_8O_{23}$) added $(K_{0.5}Na_{0.5})(Nb_{0.96}Sb_{0.04})O_3$ ceramics were fabricated using conventional mixed oxide method and their piezoelectric and dielectric properties were investigated as a fu+EY50nction of the amount of KCN addition. With increasing the amount of KCN addition, density and mechanical quality factor(Qm), electromechanical coupling factor (Kp) were increased up to 1.2 mol% and then decreased. At the 1.2 mol% KCN added specimen, mechanical quality factor (Qm), electromechanical coupling factor (Kp), density and dielectric constant (${\varepsilon}r$) showed the optimal values of 781, 0.445, $4.42\;g/cm^3$ and 443, respectively, for piezoelectric transformer application.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.234-237
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• 2000

In this paper, the structural, dielectric and piezoelectric properties of the Pb[(S $b_{1}$2/N $b_{1}$2/)$_{0.035}$- $_Mn_{1}$3/N $b_{2}$3/)$_{0.065}$-(Z $r_{0.49}$, $Ti_{0.51}$)$_{0.90}$] $O_3$ ceramics were investigated with respect to the variation of the milling time. Grain size was decreased as the increase of milling time. As the milling time is increased, the particle size of the powder was decreased. Dielectric constant and electromechanical coupling factor (Qm)were slowly increased with the increase of milling time. The highest value of Qm was 1,497 at milling time 8 hour. Temperature coefficient of resonant frequency(TC $F_{r}$) was moved to positive side with the increase of milling time.e.e.e.e.e.e.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.3
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• pp.155-160
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• 2000

The piezoelectric properties and the doping effect for$0.95Pb(Zr_xTi_{1-x})O_3+0.05Pb(Mn1/3Nb2/3)O_3$ compositions were studied. Also, the heat generation and the change of electromechanical characteristics, the important problem in practical usage, were investigated under high electric field driving. As a experiment results under low electric field, the values of kp and $\varepsilon33T$ were maximized, but Qm was minimized(Kp=0.57, Qm=1550) in the composition of x=0.51. In order to increase the values of Qm $Nb_2O_5$ was used as a dopant. As the result of that, the grain size was suppressed and the uniformity of grain was improved. Also, the values of kp decreased, and the values of Qm increased with doping concentration of $Nb_2O_5$. As a experiment results under high electric field driving, when vibration velocity was lower than 0.6[m/s], the temperature increase was $20[^{\circ}C]$, and the change ratio of mechanical quality factor was less than 10[%]. So, its electromechanical characteristics was very stable. Conclusively, piezoelectric ceramic composition investigated at this paper is suitable for application to high power piezoelectric devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.300-303
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• 2003

[ $0.91(PSN-PZT)-0.05BF-0.04PNW+0.3wt%MnO_2+0.6wt%CuO+xwt%CeO_2$ ] ceramics were fabricated with the variations of $CeO_2$ addition at the sintering temperature of $950^{\circ}C$ and their microstructure and dielectric and piezoelectric characteristics were investigated. As the amount of $CeO_2$ addition increased, the grain size, density and electromechanical coupling factor(kp) were increased and the mechanical quality factor(Qm) was decreased. At the $0.3wt%CeO_2$, density, grain size and electromechanical factor(kp) showed the maximum value of $7.87g/cm^3$, $3.22{\mu}m$ and 0.5, respectively. However, mechanical quality factor(Qm) showed the minimum value of 807 at the $0.5wt%CeO_2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.59-61
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• 2005

In this paper, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, $Pb[(Mn_{1/3},Nb_{2/3})_{0.07}(Zn_{1/3}Nb_{2/3})_a(Zr_{0.48}Ti_{0.52})_{1-0.07-a}O_3]$ ceramics were manufactured with the variations of PZN from 2 to 14mol% and their dielectric and piezoelectric properties were investigated. Sintering temperature was varied from 910 to $1000^{\circ}C$. At 8mol% PZN substituted specimen sintered at $970^{\circ}C$, electromechanical coupling factor(kp), mechanical quality factor(Qm), dielectric constant and peizoelectric constant($d_{33}$) showed the optimal values of 0.536, 1803, 1551 and 328[pC/N), respectively, for multilayer piezoelectric transformer application.