• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.764-767
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• 2004

This study was to measure the minuteness structure, dielectric properties of (0.3-x)PMN - XPSS-0.7PZT+0.5wt%NiO+0.5wt%$MnO_2$(x=0.05, 0.10, 0.15, 0.20, 0.25)ceramics according to sintering temperature and PSS moi percentage after manufacturing the specimens with a general method. the results of this study were gotten such as follows. The crystal structure of ceramic has the rombohedral structure in XRD. it appeared that addition of Ni, Mn additive was helpful to the formation of stable structure. Dielectric constant at $20^{\circ}C$ showed its maximum value 890.001 in specimens sintered at $1000^{\circ}C$, x=0.15mol. and dielectric loss showed its minimum value 6.95[%] in specimens sintered at $1000^{\circ}$, x=0.05mol. The variation rate of dielectric constant according to the change of frequency was decreased by increasing frequency, The variation rate of dielectric constant according to the change of temperature was increased by increasing temperature.

• Korean Journal of Materials Research
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• v.22 no.7
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• pp.342-345
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• 2012

The dielectric properties and phase transformation of poled <001>-oriented $Pb(Mg_{1/3}Nb_{2/3})O_3-x%PbTiO_3$(PMN-x%PT) single crystals with compositions of x = 20, 30, and 35 mole% are investigated for orientations both parallel and perpendicular to the [001] poling direction. An electric-field-induced monoclinic phase was observed for the initial poled PMN-30PT and PMN-35PT samples by means of high-resolution synchrotron x-ray diffraction. The monoclinic phase appears from $-25^{\circ}C$ to $100^{\circ}C$ and from $-25^{\circ}C$ to $80^{\circ}C$ for the PMN-30PT and PMN-35PT samples, respectively. The dielectric constant (${\varepsilon}$)-temperature (T) characteristics above the Curie temperature were found to be described by the equation$(1/{\varepsilon}-1/{\varepsilon}_m)^{1/n}=(T-T_m)/C$, where ${\varepsilon}_m$ is the maximum dielectric constant and $T_m$ is the temperature giving ${\varepsilon}_m$, and n and C are constants that change with the composition. The value of n was found to be 1.82 and 1.38 for 20PT and 35PT, respectively. The results of mesh scans and the temperature-dependence of the dielectric constant demonstrate that the initial monoclinic phase changes to a single domain tetragonal phase and a to paraelectric cubic phase. In the ferroelectric tetragonal phase with a single domain state, the dielectric constant measured perpendicular to the poling direction was dramatically higher than that measured in the parallel direction. A large dielectric constant implies easier polarization rotation away from the polar axis. This enhancement is believed to be related to dielectric softening close to the morphotropic phase boundary.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05e
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• pp.57-60
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• 2003

This paper explained electric field distribution's characteristics of dielectric pellets with a shape of ball to voltage. When discharge gap of electrode and input voltage are each 20[mm], 10000[V], the electric field simulation results of dielectric pellets with a shape of ball with relative dielectric constant of several kind measured stronger electric field near electric pellets with a shape of ball of ${\phi}5$[mm] than $1{\phi}$[mm] and $3.33{\phi}$[mm] at atmosphere. And the maximum electric field of dielectric pellets with a shape of ball over ${\phi}5$[mm] increased about 5[%] to maximum electric field of electric pellets with a shape of ball ${\phi}5$[mm]. And the result of simulation, when relative dielectric constant of dielectric pellets with a shape of ball is 100, it measured about 90[%] of maximum electric field of dielectric pellets with a shape of ball with relative dielectric constant over 1000.

• Korean Journal of Materials Research
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• v.21 no.4
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• pp.196-201
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• 2011

It is known that the relative dielectric constant of insulating polyethylene matrix composites with conducting materials (such as carbon black and metal powder) increases as the conducting material content increases below the percolation threshold. Below the percolation threshold, dielectric properties show an ohmic behavior and their value is almost the same as that of the matrix. The change is very small, but its origin is not clear. In this paper, the dielectric properties of carbon black-filled polyethylene matrix composites are studied based on the effect medium approximation theory. Although there is a significant amount of literature on the calculation based on the theory of changing the parameters, an overall discussion taking into account the theory is required in order to explain the dielectric properties of the composites. Changes of dielectric properties and the temperature dependence of dielectric properties of the composites made of carbon particle and polyethylene below the percolation threshold for the volume fraction of carbon black have been discussed based on the theory. Above the percolation threshold, the composites are satisfied with the universal law of conductivity, whereas below the percolation threshold, they give the critical exponent of s = 1 for dielectric constant. The rate at which the percentages of both the dielectric constant and the dielectric loss factor for temperature increases with more volume fraction below the percolation threshold.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.7
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• pp.305-309
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• 2003

This paper was shown the simulation of electric field distribution of globular dielectric for design of ideal packed-bed plasma reactor. When discharge gap between the electrodes and input voltage are each 20[mm]. 10000[V] in the atmosphere, the results of simulation to the electric field was measured stronger at globular dielectric of $\phi$5[mm] than 1$\phi$[mm] and 3.33$\phi$[mm]. And the maximum electric field or globular dielectric with $\phi$10[mm] was increased about 5[%] to maximum electric field of globular dielectric with $\phi$5[mm] in the atmosphere. when dielectric constant of globular dielectric is 100, it was simulated about 90[%] of maximum electric field of globular dielectric over 1000 dielectric constant. Ana the highest electric field appeared as globular electric was parallel structure with the other globular dielectric side by side of the globular dielectric and connected to electrodes.

• Journal of Biosystems Engineering
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• v.24 no.2
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• pp.123-134
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• 1999

The electrical properties such as dielectric constant, dielectric loss factor and AC conductivity of grain were presented to measure the moisture content of grain using RF impedance. At frequency ranging from 1 to 10MHz and room temperature, $20^{\circ}C$, vector network analyzer(HP4195) and coaxial type sample holder were used to analyze the electrical properties of paddy(11∼24%w.b.), brown rice(11∼18%w.b.), barley(11∼21%w.b.) and wheat(11∼23%w.b.) depending on the moisture content, frequency and bulk density. The dielectric constant and AC conductivity of grain samples increased with moisture content and bulk density. The dielectric constants decreased with frequency and could be expressed as function of the moisture density(decimal moisture $content{\times}bulk$ density).

• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.829-834
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• 1994

The aim of this study is to investigate the changes in dielectric properties, Young's modulus and remnant compressive strength with compressive cyclic loading in PZT of tetragonal, MPB and rhombohedral composition. Higher relative dielectric constants appeared in the poled condition than the unpoled condition for all the compositions. After poling treatment remarkably higher relative dielectric constants were observed particularly in MPB, tetragonal compositions. Until five percent of the expected fatigue life was exhausted, the dielectric constant increased with compressive cyclic stress in MPB and rhombohedral while it remained nearly constant in tetragonal. During the subsequent compressive cyclic stress, dielectric constant decreased in all the three compositions. As the compressive cyclic stress is applied the change of Young's modulus was coincided with the change of remnant compressive strength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.309-313
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• 1997

(Ba$_{x}$Sr$_{l-x}$)TiO$_3$(BST) thin fi1ms with various Ba/Sr ratios were deposited on Pt(80nm)/SiO$_2$(100nm)/Si by RF magnetron sputtering. BST thin films which have x=0.6, 0.5, 0.4 were studied dielectric properties with temperature variation. The frequency was used from 100Hz to 1MHz for measuring dielectric constant. The measurement conditions of dielectric constant with Temperature Variation were 1KHz and 2$0^{\circ}C$. As a result, the dielectric constant of BST thin film was about 425 and loss factor was 0.013. Also, with increasing Temperature, the dielectric constants of BST thin films were gradually decreased.sed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.802-807
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• 2001

The (S $r_{0.85}$C $a_{0.15}$)Ti $O_{3}$(SCT) thin films are deposited on Pt-coated electrode (Pt/TiN/ $SiO_2$/Si) using RF sputtering method. The composition of SCT thin films deposited on Si substrate at woom temperature is close to stoichiometry(1.102 in A/B ratio). The maximum dielectric constant of SCT thin films is obtained by annealing at 600[$^{\circ}C$]. The capacitance characteristics had a stable value within $\pm$4[%]. The drastic decrease of dielectric constant and increase of dielectric loss in SCT thin films is observed above 200[kHz]. SCT thin films used in this study show the phenomena of dielectric relaxation with the increase of frequencey.cey.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.1
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• pp.43-47
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• 2001

Plasma polymerized hexamethyldisiloxane thin film was fabricated by employing an inter-electrode capacitively coupled type apparatus under the following conditions : carrier gas flow rate of 11 sccm, reaction pressure of 0.1 torr, discharge frequency of 13.56 MHz and discharge power of 30∼90 W. Polymerization rate of thin film fabricated at the discharge power of 90W is 32.5nm/min. Relative dielectric constant and dielectric loss tangent of thin film shows 3.2∼3.8 and 2.6x10$\^$-3/∼4.51x10$\^$-3/ respectively in the frequency range of 1 kHz∼1 MHz. As the annealing temperature is increased, the relative dielectric constant gradually decreases while the dielectric loss tangent increases. The current density increase gradually with increasing annealing temperature and electric field. The electric conduction of the heaxamethyldisiloxane thin film shows Schottky effect.