• Transactions on Electrical and Electronic Materials
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• v.6 no.5
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• pp.202-209
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• 2005

Phase evolution, microstructure and the electrical properties such as $k_p$ and $Q_m$ of $Pb(Mg_{1/3}Nb_{2/3})O_3[PMN]-Pb(Mn_{1/3}Nb_{2/3})O3[PM'N]-PbZrO_3[PZ]-PbTiO_3[PT]$ quaternary system were investigated within the compositional ranges $0{\leq}y{\leq}0.125$, y+z=0.125, and $0.39{\leq}x{\leq}0.54$ of the formula $Pb_{0.97}Sr_{0.03}[Mg_{1/3}Nb_{2/3})_y\;(Mn_{1/3}Nb_{2/3})_z\;(Zr_{x}Ti_{1-x})_{1-(y+z)}]O_3$. In the case of increasing Mn/(Mg+Mn) ratio for a fixed Zr/Ti ratio of 47.5/52.5, phase relation remained unchanged but the grain size drastically decreased, and the electrical properties changed as following: both $k_P$ and $Q_m$ reached the peak values at $Mn/(Mg+Mn)\cong0.3l7$ and gradually decreased; $\varepsilon33^T$ showed a monotonic decrease; P-E hysteresis loop gradually changed to asymmetrical one, and $E_i$ increased in correspondence. With increasing Zr/Ti ratio for a fixed Mn/(Mg+Mn) ratio of 0.317, on the contrary, the cell parameter $(\alpha^2c)^{1/3}$ gradually increased, and tetragonal-rhombohedral morphotropic phase boundary appeared in the range of $51/49{\leq}Zr/Ti{\leq}54/46$. the meantime, the grain size substantially increased, and the electrical properties changed as following: $k_P$ and $\varepsilon33^T$ reached peak values at Zr/Ti=51/49 and 48/52, respectively, and then gradually decreased; change of $Q_m$ was adverse to $k_P$; both $E_C\;and\;E_i$ considerably decreased while $P_S$ moderately increased. For the system 0.125(PMN+PM'N)-0.875PZT studied, the composition Mn/(Mg+Mn)=0.3l7 and Zr/Ti=51/49 revealed some promising electrical properties for piezoelectric transformer application such as $k_P=0.58,\;Q_m\cong1000$, and $\varepsilon^T_{33}=970$, as well as dense and fine-grained microstructure.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.279-282
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• 2003

In this paper, to apply piezoelectric transformer for PDA backlight inverter, piezoelectric transformer using the composition which $Nb_2O_5$ added into PNW-PMN-PZT ceramics was fabricated as Rosen-type one with the size of $1165mm^3$. And their electrical characteristics were investigated with the variations of load resistance and driving frequency And then, the driving circuit for PDA CCFL(0.6W) which composed of the two MOSFETs connecting in series was manufactured using piezoelectric transformer, VCO and one-chip microprocessor. After driving for 25 min using the proposed circuit for PDA CCFL(0.6W), driving frequency of 214.4kHz, input voltage of 31.78 V and input current of 21.1mA were shown. And then, output voltage of 293.2 V and output current of 2.2mA were shown. At the same time, efficiency of 96.2$\%$ and temperature rise of $3.6^{\circ}C$ were appeared at the piezoelectric transformer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.227-231
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• 2008

In this study, in order to improve the electrical properties of low temperature sintering piezoelectric ceramics, $[0.05Pb(Zn_{1/2}W_{1/2})-0.07Pb(Mn_{1/3}Nb_{2/3})-0.088Pb(Zr_{0.48}Ti_{0.52})]O_3$(abbreviated as PZW-PMN-PZT) ceramic systems were fabricated using $Bi_2O_3$, CuO and $Li_2CO_3$ as sintering aids and then their piezoelectric and dielectric properties were investigated according to the amount of $Li_2CO_3$ and post-annealing process. Post-annealing process enhanced all physical properties except for mechanical quality factor (Qm). 0.2 wt% $Li_2CO_3$ added and post-annealed specimen showed the excellent values suitable for low loss piezoelectric actuator application as follow: the density = 7.86 $g/cm^3$ electromechanical coupling factor (kp) = 0.575, piezoelectric constant $d_{33}$ = 370 pC/N, dielectric constant ($\varepsilon_r$) = 1546, and mechanical quality factor (Qm) = 1161, respectively.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.981-983
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• 1999

In this paper, the electrical characteristics of $\lambda$ vibration-mode piezoelectric transformer for applying to CCFL driving inverter was investigated. Piezoelectric transformer was made of PZT - PMN - 0.5wt% $Nb_{2}O_{5}$ composition. As a results of the electrical characteristics of piezoelectric transformer, when applied voltage was $35[V_{rms}]$ in $100[k{\Omega}]$ load resistance, output voltage was about $710[V_{rms}]$ and output power was more than 2[W]. As output power increased, step-up ratio and temperature was very stable until output power was 2.5[W]. Also, Efficiency was maximum in $70[k{\Omega}]$ load resistance, and about 89[%]. Also, when CCFL was used as load, the maintaining voltage was $700[V_{rms}]$ and the luminescence was $2000[cd/m^2]$ in applying $25[V_{rms}]$ to piezoelectric transformer. Conclusively, piezoelectric transformer fabricated in this paper can be applied to piezoelectric inverter for CCFL driving.

• Korean Journal of Materials Research
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• v.15 no.7
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• pp.453-457
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• 2005

Piezoelectric properties of $Pb(Mn_{1/3}Nb_{2/3})O_3-PbZrO_3-PbTiO_3$ ceramics were investigated with $Al_2O_3$ content $(0.0-1.0 wt\%)$. The constituent phases, microstructure, electromechanical coupling factor, dielectric constant, piezoelectric charge and voltage constants were analyzed. Diffraction peaks for (002) and (200) planes were identified by X-ray diffractometer for all the specimens doped with $Al_2O_3$, indicating the MPB (morphotropic phase boundary) composition of tetragonal structures. The highest sintered density of $7.8 g/cm^3$ was obtained for $0.2wt\%\;Al_2O_3-doped$ specimen. Grain size increased by doping $Al_2O_3$ up to $0.3 wt\%$, and it decreased by more doping. Electromechanical coupling factor, dielectric constant, piezoelectric charge and voltage constants increased by doping $Al_2O_3$ up to $0.2wt\%$, and it decreased by more doping. This might result from the formation of oxygen vacancies due to defects in $O^{2-}$ ion sites and the substitution of $Al^{3+}$ ions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.6
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• pp.480-486
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• 2021

Magnetoelectric (ME) composite is composed of a piezoelectric material and a magnetostrictive material. Among various ME structures, 2-2 type layered ME composites are anticipated to be used as high-sensitivity magnetic field sensors and energy harvesting devices especially operating at its resonance modes. Rosen type piezoelectric transducer using piezoelectric material is known to amplify a small electrical input voltage to a large electrical output voltage. The output voltage of these Rosen type piezoelectric transducers can be further enhanced by modifying them into ME composite structures. Herein, we fabricated Rosen type ME composites by sandwiching Rosen type PMN-PZT single crystal between two Ni layers and studied their ME coupling. However, the voltage step-up ratio at the resonance frequency was found to be smaller than the value calculated with α_ME value. The ATILA FEA (Finite Elements Analysis) simulation results showed that the position of the nodal point was changed with the presence of a magnetostrictive layer. Thus, while designing a Rosen type ME composite with high performance in a resonant driving situation, it is necessary to optimize the position of the nodal point by optimizing the thickness or length of the magnetostrictive layer.