• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.5
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• pp.471-479
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• 2022

Recently, piezoelectric devices, such as ultrasonic surgery, ultrasonic atomizer, and ultrasonic speaker, are analyzed and designed by finite element simulation methods. However, the discrepancy between the design and the experiment results of the device typically occurs due to the inaccuracy of the piezoelectric material properties. To improve the simulation accuracy, the material properties of the PZT ceramics were better refined using parameter estimation method. The material parameters are elastic stiffness c^E_ij and piezoelectric constant e_ij of PZT ceramics. The impedance curve characteristics for the LTE mode of PZT ceramics were calculated. The mismatch between the simulation and the experimental data were compared and minimized by a least square method. Finally, the simulated impedance data were compared with the experimental data for the various vibration modes of PZT ceramics and the optimized material properties of PZT ceramics were verified. To further verify the accuracy, this method was also applied to piezoelectric PMN-PT single crystals.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.293-295
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• 1991

In this study, we investigated the possibilty that $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3-PbZrO_3$ ceramics with strontium substitutions could be used for piezoelectric sounders. Piezoelectric buzzer is one of them. By partially substituting Sr for Ph, dielectric constants had values greater than 2000, the value proper piezoelectric buzzer, piezoelectric constant($d_{31}$) had a maximum value, 298 $[10^{-12}C/N]$, at the Sr 5 mol % substitution. Sound level of piezoelectric buzzer had the highest value of 91 dB at the Sr 5 mol % substitution.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.759-761
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• 1992

$0.10Pb(Sb_{1/2}Sn_{1/2})O_3-0.25PbTiO_3-0.65PbZrO_3+MnO_2(0.18mol%)$, NiO(0.15mol%) temary compound ceramics won fabricated by the mixed-oxide method. Noise properties of the pyroelectric infrared sensor were investigated with particle size of the raw materials and gain size of the specimens. Particle size were decreased and sintered density, voltage resposivity were increased with increasing the ball-mill times. The specimen ball-milled for a 80[hr] showed a good pop-corn noise properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.377-380
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• 2001

The BST thin films to composite (Ba$\sub$x/Sr$\sub$l-x/)TiO$_3$ using sol-gel method were fabricated on Pt/Ti/SiO$_2$/Si substrate. The thin film capacitor to be ferroelectric materials was investigated by structural and electrical properties. BST solution was composited by moi ratio, and then spin-coated (from 3 times to 5 times coating on Pt/SiO$_2$/Si substrate. Thickness of BST ceramics thin films are about 2600∼2800[${\AA}$] in 3 times deposition. The property of leakage current was stable when the applied voltage was 3[V]. Leakage current of 3 times coated BST thin film was 10$\^$-9/∼10$\^$-11/[A] at 0∼3[V].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1989.06a
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• pp.70-73
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• 1989

(1-x-y)Pb($Zn_{1/3}Nb_{2/3})O_3-Ba(Zn_{1/3}Nb_{2/3})O_3-PbTiO_3(0.12{\leq}x{\leq}0.21, 0.24{\leq}y{\leq}0.33$) ternary compound ceramics were fabricated by the mixed oxide method. The sintering temperature and time were 1050 [$^{\circ}C$], 2[hr]. Morphotropic phase boundary region was chosen for the composition. 0.55 PZN-0.21 BZN-0.24 PT specimen had the highest value of relative dielectric constants, 5353. The curie temperature of specimens were increased linearly with PT content. Near the morphotropic phase boundary, electro-mechanical coupoling factor and mechanical quality factor of the specimens had the highest values.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.620-623
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• 2003

Non-linear behaviors of multilayer piezoelectric ceramic actuator (MCA) were investigated under electrical and mechanical stress. DC 100 V bias was applied to the MCA to obtain displacement. Laser vibrometer, which using Doppler effect, was employed to characterize displacement caused by $d_{33}$ mode of MCA. To understand this non-linear behavior of MCA, displacement was measured and compared under different load states. By increasing load, electric field-induced strain and piezoelectric constant($d_{33}$) of MCA was decreased. We attribute this phenomenon to the domain wall motion and depoling of MCA under heavy load.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.283-286
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• 2000

In this study, the acoustic transducer of a thin circular disc-type with PZT/Metal was manufactured. The piezoelectric transducer with 200kHz resonance frequency was designed by considering the sharp directivity and the sound pressure. The dielectric and piezoelectric properties of 0.5 weight percent $MnO_2$ and NiO doped $0.1Pb(Mg_{1/3}Nb_{2/3})O_3-0.45PbTiO_3-0.42PbZrO_3$ ceramics were investigated aiming at acoustic transducer applications. Also, the acoustic characteristics of a thin circular disc-type with metal-piezoceramics have been Investigated.

• The Korean Journal of Ceramics
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• v.4 no.3
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• pp.204-206
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• 1998

The Gibbs free energy of formation of $BaThO_3$ from elemental oxides has been measured at temperatures between 853 and 903 K using a $CaF_2$ solid electrolyte galvanic cell. The galvanic cell consisted of Pt, $O_2, CaO+CaF_2 \parallel CaF_2 \parallelBaThO_3+ThO_2+BaF_2, O_2$, Pt EMF gave the standard Gibbs free energy for the reaction $CaF_2+BaThO_3=CaO+BaF_2+ThO_3$ as $\DeltaG^o$,/TEX>=124111.031-117.597 T(J/mol).

• The Korean Journal of Ceramics
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• v.4 no.2
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• pp.103-113
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• 1998

By using a gas-tight electrochemical cell, we can perform high-temperature coulometric titration and measure electronic transport properties to determine the elecronic defect structure of metal oxides. This technique reduces the time and expense required for conventional thermogravimetric measurements. The components of the gas-tight coulometric titration cell are an oxygen sensor, Pt/yttria stabilitized zirconia(YSZ)/Pt, and an encapsulated metal oxide sample. Based on cell design, both transport and thermodynamic measurements can be performed over a wide range of oxygen partial pressure ($pO_2=10^{-35}$ to 1 atm). This paper describes the high-temperature gas-tight electrochemical cells used to determine electronic defect structures and transport properties for pure and doped-oxide systems, such as YSZ, doped and pure ceria $(Ca-CeO_2 \;and\; CeO_2)$, copper oxides and copper-oxide-based ceramic superconductors, transition metal oxides, $SrFeCo_{0.5}O_x,\; and \;BaTiO_2$.

• The Korean Journal of Ceramics
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• v.1 no.4
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• pp.204-208
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• 1995

The microstructure and electrical propetries were investigated for polycrystalline $Ba^{1-x}Sr_xTiO_3$(BST) thin films deposited on Pt/Ti/$SiO_2$(PTSS) and Pt/MgO(PM) substrates by metalorganic chemical vapor deposition (MOCVD). BST films on PTSS have coulmnar and porous structures, while on PM have an equiaxied and dense structure. The dielectric constant and a dissipation factor of BST films on PTSS and 20 fC/$\mu \textrm{cm}^3$ on PTSS and 12fC/$\mu \textrm{cm}^2$ on PM was obtained at an applied electric field of 0.06 MV/cm. Leakage current density of BST films on PM was smaller than that on PTSS. The leakage current density level was about $8\times10^{-8}A/\textrm{cm}^2$ at 0.04MV/cm.