• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.10
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• pp.870-875
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• 2002

Ba(Zn$_1$-xCox)TaO$_3$[BZCT] ceramics were Prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of 1450∼1550$\^{C}$ for 5 hr in air. The crystal structure of BZCT ceramics was investigated by the XRD. The microstructure of the specimens were observed by SEM. The structural properties of BZCT specimens were investigated as a function of composition and sintering temperature. All BZCT ceramics sintered over 1550$\^{C}$ were showed a polycrystalline complek perovskite structure without second phases and any unreacted materials. The density of BZCT (70/30) specimen sintered at 1550$\^{C}$ was 6.31g/㎤. In the case of the BZCT(70/30) ceramics sintered at 1550$\^{C}$ for 5 hours, dielectric constant, qualify factor and temperature coefficient of resonant frequency for microwave dielectrics application were a good value of 29, 16,468 at 10㎓ and -4.4 ppm/$\^{C}$, respectively.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.150-161
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• 2016

The conventional brick-layer model is not satisfactory either in theory or in practice for the description of dispersive responses of polycrystalline solid electrolytes with current-constriction effects at the grain boundaries. Parallel networks of complex dielectric functions have been shown to successfully describe the AC responses of polycrystalline sodium conductors over a wide temperature and frequency range using only around ten model parameters of well-defined physical significance. The approach can be generally applied to many solid electrolyte systems. The present work illustrates the approach by simulation. Problems of bricklayer model analysis are demonstrated by fitting analysis of the simulated data under experimental conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.203-204
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• 2008

In this study, in order to develop the multilayer piezoelectric actuator and ultrasonic resonator, PMN-PNN-PZT ceramics were fabricated by the variations of ball size at sintering temperature of $900^{\circ}C$ and their piezoelectric and dielectric characteristics were investigated as a function of the variations of ball size. When the ball size was 3mm$\phi$, density, dielectric constant$({\varepsilon}r)$, electromechanical coupling factor(kp) and piezoelectric d constant$(d_{33})$ were increased. At the ball size of 3mm$\phi$, the specimen showed the optimum values of density=7.909g/$cm^3$, kp=0.592, Qm=1292, $d_{33}$=368pC/N, $\varepsioln_r$=1502, respectively.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.995-998
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• 2003

This paper reports the correlation between dielectric constant and degree of amorphism of the hybrid type Si-O-C thin films. Si-O-C thin films were deposited by high density plasma chemical vapor deposition using bistrimethyl- silylmethane(BTMSM, $H_{9}$C$_3$-Si-C $H_2$-Si-C$_3$ $H_{9}$) and oxygen precursors with various flow rate ratio. As-deposited film and annealed films at 40$0^{\circ}C$ were analyzed by XRD. The Si-O-C thin films were amorphous from XRD patterns. For quantitative analysis, the diffraction pattern of the samples was transformed to radial distribution function by Fourier analysis, and then compared with each other. The degree of amorphism of annealed films was higher than that of as-deposited ones. The dielectric constant varied in accordance with flow rate ratio of precursors. The lowest dielectric constant was obtained from the as-deposited film which has the highest degree of amorphism after annealing.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.797-803
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• 2001

The on-line cure monitoring of fiber reinforced thermosetting resin matrix composite material was performed for the better quality and productivity during manufacturing. Since the dissipation factor measured by dielectrometry method is dependent on the degree of cure and temperature of resin, in this study, a new method to obtain the degree of cure during on-line cure monitoring for glass/polyester composites was developed by employing a combination function of the temperature and the dissipation factor. Two sensor signals from a K-type thermocouple and an interdigitated dielectric sensor were processed during curing process under various cure cycles. The DSC (Differential Scanning Calorimetry) data was also used for the reference of degree of cure.

• Journal of the Korean Ceramic Society
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• v.30 no.1
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• pp.1-6
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• 1993

Dielectric and piezoelectric porperties of pseudoternary xPb(Al2/3W1/3)O3-(1-x)Pb(Zr0.52Ti0.48)O3 (x=1~10mol%) ceramic system have been investigated as a function of the amount of PAW[Pb(Al2/3W1/3)O3] and sintered from 110$0^{\circ}C$ to 120$0^{\circ}C$ for 1hr. As the amount of PAW increases, the c/a of tetragonal structure decreases. The grain size was reduced with increasing the amount of PAW addition. However, the density, dielectric constant and electromechanical coupling factor(kp) exhibited a maximum value at the amount of 5mol% PAW addition.

• Journal of the Korean Ceramic Society
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• v.30 no.1
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• pp.78-84
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• 1993

In PMN-pyrochlore phase mixtures, dielectric constant was measured as a function of the volume fraction of pyrochlore phase and considered with general effective media(GEM) equation. For the application of GEM equation to this system, the critical volume fraction(Vc) where connectivity between the perovskite PMN and pyrochlore phase changed from 0-3 to 3-3, was determined based on the each particle size ratio of two phases with microstructural observation. And then the t value was determined from modified percolation powder-law dependence ( K-Kc (V-Vc)t). In the case of applying such values of t and Vc to the GEM equation, which provided a reasonable fit to the measured dielectric constant within the experimental error range.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.161-164
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• 2004

In this study, to develop the composition ceramics for the Ultrasonic vibrator, $Pb(Mn_{1/3}Nb_{2/3})O_3Pb(Zr.Ti)O_3$ system ceramics were manufactured as a function of PCN substitution. Its dielectric and piezoelectric characteristics were investigated. With increasing the amount of PCN substitution, electromechanical coupling factor(kp) were increased until 3mol% PCN and that after decreased. mechanical quality factor(Qm) showed the maxinum value at 2mol% PCN. Eletromechanical coupling factor, mechanical quality factor and dielectric constant were showed optimum value at PCN 2mol% as 0.58, 1630 and 1407, respectively for ultrasonic vibrator applications.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.1
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• pp.115-120
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• 2004

An indoor air cleaner consisting of a dielectric barrier discharge system and an electrostatic precipitator (ESP) was experimentally investigated. The function of the dielectric barrier discharge is to precharge particles by producing nonthermal plasma before indoor air enters ESP, leading to an enhancement in dust collection efficiency. The dependence of particle size distribution on the plasma discharge was examined to understand the mechanism of the particle precharging. The plasma discharge was found to increase the electrical force of the particles, rather than agglomerate them. Coarse particles in the range of 0.5 to $5.0{\mu}m$ were observed to be easily collected by this indoor air cleaner, and the present study laid emphasis on the removal of fine particles of $0.3{\mu}m$. The collection efficiency of the fine particles was largely enhanced by the plasma discharge.

• Journal of the Korean Ceramic Society
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• v.26 no.6
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• pp.755-762
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• 1989

A pyroelectric ceramic material based on Pb(Sn1/2Sb1/2)O3 modified PZT system is studied as a function of the amount of Pb(Sn1/2Sb1/2)O3 and PbTiO3. With increasing the Pb(Sn1/2Sb1/2)O3 amount the dielectric constant increases up to 10mol% and then decreases, but the pyroelectric coefficient decreases and as the PbTiO3 contents increase in the 10mol% added PZT system, the dielectric constant increases but the infrared sensitivity decreases. The good pyroelectric material has low dielectric constant and no pyrochlore phase, but does not depend in the amount of remanent dipole, and its composition sites around ferroelectric-to-antiferroelectric phase boundary.