• Journal of the Korean Ceramic Society
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• v.33 no.8
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• pp.895-900
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• 1996

Ba(Ti1-xSnx)4O9 powder was synthesized by oxalate method. With the substitution of Sn into Ti site the sintered BaTiO4 crystal phase was stabilized due to the formation of solid solution. The optimal amounts of Sn solutbility for formation of BaTi4O9 crystalline phase was 0.16mole and of Sn was substituted and sintering was done at 135$0^{\circ}C$ for 30 minutes long rod type crystal was well developed and the highest Q value was obtained. But dielectric constant wasnearly constant without regarding to the Sn addition and the sintering time.

• Journal of the Korean Ceramic Society
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• v.33 no.5
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• pp.556-562
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• 1996

In order to understand the electrostrictive behavior of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) solid solutions the dielectric constants the electric-field-induced strains and the pyroelectric coefficients of (1-x)PMN-xPT (x=0.1-0.4) were investigated in the temperature range -50~20$0^{\circ}C$. For x=0.1~0.35 where the phase transi-tion is diffusive the strain has a maxima at the temperature of maximum pyroelectric coefficient (depolrizing temperature) rather than the temperature of maximum dielectric constant. For x=0.4 where the phase transition is relatively sharp the strain decreases monotonically as the temperature increases. Relationships among the above experimental results are discussed.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.171-177
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• 2016

Rhombohedral $Ba(Ti_{0.92}Zr_{0.08})O_3$ single crystals are fabricated using the cost-effective solid-state single crystal growth (SSCG) method; their dielectric and piezoelectric properties are also characterized. Measurements show that (001) $Ba(Ti_{0.92}Zr_{0.08})O_3$ single crystals have an electromechanical coupling factor ($k_{33}$) higher than 0.85, piezoelectric charge constant ($d_{33}$) of about 950 [pC/N], and piezoelectric voltage constant ($g_{33}$) higher than 40 [${\times}10^{-3}Vm/N$]. Especially the $d_{33}$ of (001) $Ba(Ti_{0.92}Zr_{0.08})O_3$ single crystals was by about six times higher than that of their ceramics. Because their electromechanical coupling factor ($k_{33}$) and piezoelectric voltage constant ($d_{33}$, $g_{33}$) are higher than those of soft PZT ceramics, it is expected that rhombohedral (001) $Ba(Ti_{0.92}Zr_{0.08})O_3$ single crystals can be used as "lead-free" piezoelectric materials in many piezoelectric applications such as actuator, sensor, and transducer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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• pp.637-640
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• 2017

In this study, $(1-x)(Na_{0.52}K_{0.443}Li_{0.037})(Nb_{0.883}Sb_{0.08}Ta_{0.037})O_3-x(Bi_{0.5}(Na_{0.7}K_{0.3})_{0.5}ZrO_3$ ceramics were fabricated by BNKZ substitution using a conventional solid-state method to develop excellent lead-free piezoelectric ceramics for piezoelectric actuators; their dielectric and piezoelectric properties were then investigated. All specimens were in the orthorhombic phase. $NKL-NSTO_3$ ceramics with x=0.01 showed excellent piezoelectric properties. The density (${\rho}$), piezoelectric charge constant ($d_{33}$), planar piezoelectric coupling coefficient ($k_p$), mechanical quality factor ($Q_m$), and dielectric constant (${\varepsilon}_r$) had optimized values of $4.56g/cm^3$, 208 pC/N, 0.43, 96, and 975, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.3 s.36
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• pp.235-241
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• 2005

Incorporation of solid electrodes frequently involves plasma-based processing. The effect of plasma can influence the physical characteristics, depending on the magnitude in plasma. The undesired feature of plasma-induced damage should be prevented in characterizing the ultra-thin materials, such as ultra-thin films and organic monolayers. The current work at first proves the applicability of a liquid phase electrode in the electrical/dielectric properties through comparative work using Al and Hg on ultrathin $Al_2O_3$ films deposited through atomic layer deposition at low temperature: Two types of metals such as Aluminum (Al) and mercury (Hg) were used as electrodes in $Al_2O_3$ thin films in order to investigate the effect of electrode preparation on the current-voltage characteristics and impedance features as a function of thickness in $Al_2O_3$ film thickness. The success of Hg in $Al_2O_3$ thin films is applied to the AC and DC characterization of the organic monolayers obtained using the Langmuir-Blodgett method. From the DC current-voltage characteristics, the diode-like response is found to originate from the bulk response of the organic materials, evidenced by the fact and the capacitance is inversely related to the absolute thickness of organic layers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.608-612
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• 2016

In this study, in order to develop relaxor ferroelectric ceramics for refrigeration device application with large electrocaloric effect and low sintering temperature, PLZT(8/65/35) ceramics was fabricated using conventional solid-state method with the variation of sintering temperature ($1,050^{\circ}C$, $1,100^{\circ}C$, $1,200^{\circ}C$). The XRD pattern of all specimens indicated general perovskite structure with secondary phase. From the results of temperature dependence of dielectric constant, the $T_C$ (ferroelectric-paraelectric phase transition temperature) was shifted toward high temperature with increasing sintering temperature. When the specimen was sintered at $1,100^{\circ}C$, the optimal value of ${\Delta}T{\sim}0.349^{\circ}C$ in ambient temperature of $215^{\circ}C$ was appeared. It is considered that PLZT(8/65/35) ceramics possess the possibility of refrigeration device application.

• Journal of the Korean Ceramic Society
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• v.20 no.3
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• pp.227-235
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• 1983

The dielectric and piezoelectic properties in which $(Zr_{0.52} Ti_{0.48})^{+4}$ ions of $Pb(Zr_{0.52} Ti_{0.48})O_3$ are partially substituted for $W^{+6}$ ions were studied. $ZrTiO_4$ was made by coprecipitation. The specimens of disc shape were sintered respectively at 1180$^{\circ}$to 130$0^{\circ}C$ at an intervals of 2$0^{\circ}C$ for 1 hour. The optimum sintering temperature were found to be between 126$0^{\circ}C$ and 128$0^{\circ}C$. PZT solid solutions sintered had the tetragonal structure with c/a=1.025$\pm$0.005 and theoretical densities incre-ased from 8.02 to 8.17g/cm3 with increasing the amount of the partial substitution of $(Zr_{0.52} Ti_{0.48})^{+4}$ ion for $W^{+6}$ ion The grain size and curie temperature decreased with increasing the amount of $WO_3$ while the dielectric constant increased. When $(Zr_{0.52} Ti_{0.48})^{+4}$ ion was substituted for 1 mole% of $W{+6 ]$ion the planar coupling coefficient$(K_P)$ was as high as 0.58 But as the amount of $WO_3$ increased the mechanical quality factor(Qm) decreased considerably.

• Transactions on Electrical and Electronic Materials
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• v.13 no.6
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• pp.297-300
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• 2012

Lead-free (1-x)$(Na_{0.5}K_{0.5})NbO_3-xLiNbO_3$, i.e., NKN-LNx (x=0.0, 0.1, 0.2, 0.3, 0.4 mol) was prepared using the conventional solid state reaction method. The effects of LN mixing on the ferroelectric properties of NKN-LNx ceramics were studied using a dielectric constant and P-E (Polarization-electric field) measurements. Ferroelectricity was observed in the composition for x approximately varying between 0.0 and 0.4. Minimum remanent polarization $2P_r=5C/cm^2$ was achieved in the composition for x = 0.2. The ferroelectric phase transition temperature $T_C$ increased with increasing LN content. The ferroelectric phase transition of NKN-LNx ($x{\geq}0.1$) is a second-order phase transition, and that of NKN-LNx ($x{\leq}0.2$) is a first-order phase transition. These results indicate that the ferroelectric phase transition temperature of NKN-LNx change from that of second-order to weak first-order phase transition according to the LN content.

• 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.

• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1544-1553
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• 2005

In this article, a micro cantilever array actuated by PZT films is designed and fabricated for micro fluidic systems. The design features for maximizing tip deflections and minimizing fluid leakage are described. The governing equation of the composite PZT cantilever is derived and the actuating behavior predicted. The calculated value of the tip deflection was 15 ${\mu}m$ at 5 V. The fabrication process from SIMOX (Separation by oxygen ion implantation) wafer is presented in detail with the PZT film deposition process. The PZT films are characterized by investigating the ferroelectric properties, dielectric constant, and dielectric loss. Tip deflections of 12 ${\mu}m$ at 5 V are measured, which agreed well with the predicted value. The 18 ${\mu}l/s$ leakage rate of air was observed at a pressure difference of 1000 Pa. Micro cooler is introduced, and its possible application to micro compressor is discussed.