• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.461-461
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• 2010

For a low dielectric constant inter-metal dielectric application, the low-k SiCOH film with a dielectric constant of 2.8-3.2 has been deposited by plasma-enhanced chemical vapor deposition with decamethylcyclopentasiloxane, cyclohexane, and helium which is carrier gas. In this work, we investigated chemical deposition rate, dielectric constant, characterization of plasma polymer films according to temperature(25C-200C) of substrate and change of component concentration. We measured impedance by using V-I prove during process. From experimental result, deposition rate decrease with increasing temperature. Through real time impedance analysis of chamber, we find corelation between film thickness and impedance by assuming equivalent circuit.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.131-137
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• 2004

In this paper, we proposed the method of the characteristic impedance and effective dielectric constant calculations of a parallel-two-wire transmission line coated with multi-layer dielectric material using conformal mapping method. First of all, we calculated the capacitance of the transmission line when coated by N layer dielectric material which has different thickness and dielectric constant and calculated the characteristic impedance and effective dielectric constant using calculated capacitances. When compared with the Maxwell 2D (made by Ansoft Corporation) simulation result calculated result was very similar to the simulation result within the four percent error range.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.254-255
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• 2008

In this study, electrical properties of polyethylene of raised temperature resistance (PE-RT) have been studied through an examination of AC conductivity, dielectric constant, and space charge distributions. A dielectric constant was investigated by Dielectric Analyzer (DEA). Measurements of space charge distributions for PE-RT were carried out using Pulsed Electroacoustic (PEA) techniques, and it was possible to observe the negative charge near the cathode overlapped with the positive induced charge peak, the polarity of which remains unchanged after a short circuit.

• Journal of the Korean Ceramic Society
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• v.45 no.4
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• pp.208-213
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• 2008

In this study, helical antenna with microwave ZST ceramics was designed using finite element method and developed. Studied parameters are relative dielectric constant of the dielectric core and the width of the conduction metal band of the antenna. As shown in the results, the center frequency of the antenna was decreased as the dielectric constant increased. Also beam width of the antenna increased as both the dielectric constant and the conduction band width increased. Based on the designed optimal shape, the manufactured antenna has the good beam width at center frequency 1.58 GHz.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.1
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• pp.85-91
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• 2013

This paper studied surface discharge characteristics by a dielectric constant and diameter of solid dielectrics in $N_2/O_2$ mixture gas. Applied electric field strength at $N_2/O_2$ mixture gas was changed from the dielectric constant and diameter of the solid dielectrics, and insulation performance of the $N_2/O_2$ mixture gas determined surface discharge voltage. In each of the diameter at the solid dielectrics, the surface discharge voltage was increased by lengthening surface distance, whereas increasing rate of the surface discharge voltage was different from gas pressure. Thus, In this paper, main factors of surface discharge are as follows. 1) Insulation performance of $N_2/O_2$ mixture gas, 2) Dielectric constant of solid dielectrics, 3) Surface discharge path. It was clear that the surface discharge voltage depend on the main factors. These results will be applied to useful data for an eco-friendly composite insulation design.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.185-187
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• 1993

0.15BaO-$0.15Sm_2O_3-0.7TiO_2$, ceramics were fabricated by mixed-oxide method. Microwave dielectric properties were investigated with sintering temperature and annealing time. In the specimen sintered at 1350[$^{\circ}C$], dielectric constant, quality factor and temperature coefficient of resonant frequency had a good values of 80.19, 2006 (at 4.6851[GHz]), -27.54[ppm/$^{\circ}C$], respectively. Increasing the annealing time, dielectric constant was almost constant and quality factor was increased. Temperature coefficient of resonant frequency was minimum value (-1.28[ppm/$^{\circ}C$]) at 4 [hr] annealed.

• Korean Journal of Materials Research
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• v.21 no.7
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• pp.391-395
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• 2011

The structure and dielectric properties of poled <001>-oriented 0.7Pb($Mg_{1/3}Nb_{2/3})O_3-0.3PbTiO_3$ (PMN-0.3PT) crystals have been investigated for orientations both parallel and perpendicular to the [001] poling direction. An electric field induced monoclinic phase was observed for the initial poled sample. The phase remained stable after the field was removed. A quite different temperature dependence of dielectric constant has been observed between heating and cooling due to an irreversible phase transformation. The results of mesh scans and temperature dependence of the dielectric constant demonstrate that the initial monoclinic phase changes to a single domain tetragonal phase at 370K and to a paraelectric cubic phase at 405K upon heating. However, upon subsequent cooling from the unpoled state, the cubic phase changes to a poly domain tetragonal phase and to a rhombohedral 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 of 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 and at the phase transition temperature.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.11
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• pp.603-608
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• 2000

$(Ba, Sr)TiO_{3}$[BST] thin films were fabricated on the Pt/TiO$_2$/SiO$_2$/Si substrate by the RF sputtering. The structure and dielectric properties of the BST thin films with the substrate temperature were investigated. Increasing the substrate temperature, The BST phase increased and barium multi titanate phases decreased. Increasing the frequency, the dielectric constant decreased and the dielectric loss increased. The dielectric constant and dielectric loss of the BST thin films deposited at 50$0^{\circ}C$ were 300 and 0.018, respectively at 1 kHz. The leakage current density of the BST thin films deposited at 50$0^{\circ}C$ was $10^{-9}$ A/$\textrm{cm}^2$ with applied voltage of 3V. Because of the high dielectric constant(300), low dielectric loss(0.018) and low leakage current($10^{-9}$ A/$\textrm{cm}^2$), BST thin films deposited at 50$0^{\circ}C$ is expecting for the application of DRAM.

• Electrical & Electronic Materials
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• v.8 no.4
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• pp.413-417
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• 1995

In order to elucidate the electrical and mechanical properties of insulating paper, it is desirable to study the performances of tensile strength, dielectric constant, dielectric strength. In this work, we constructed the characteristics depending on change of fabrication condition, and these specimens were manufactured by hot press method. As a result, tensile strength was about 75MPa and breakdown was above 5 kV/mm at the minimum value.