• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.11
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• pp.926-929
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• 2012

The $Sr_{0.7}Bi-{2.3}Nb_2O_9$(SBNO) thin films were deposited on Si substrate by RF magnetron sputtering method at $300^{\circ}C$ of substrate temperature. And the SBNO thin films were annealed at $650{\sim}800^{\circ}C$ using RTA (rapid thermal annealing). The grain of SBNO thin films were increased with the increase of annealing temperature. The dielectric constant (100) of SBNO thin film was obtained by RTA above $750^{\circ}C$. The voltage dependence of dielectric loss showed a value within 0.03 in voltage ranges of -5~+5 V. Also, the dielectric constant characteristics showed a stable value with the increase of frequency.

• KIEE International Transactions on Electrophysics and Applications
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• v.2C no.6
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• pp.281-286
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• 2002

The temperature accelerated dielectric breakdown strength of on-wafer low-k dielectric polymer films with thicknesses ranging from 94 nm to 1141 nm is investigated by using the current-voltage characteristic measurements with MIS structures. The temperature dependence of dielectric strength is demonstrated to be Arrhenious for all thicknesses. However, the activation energy is found to be strongly thickness dependent. It follows an exponential relationship rather than being a single value, i.e., the activation energy increase significantly as film thickness increases for the thickness below 500 nm, but it is almost constant for the thickness above 500 nm. This relationship suggests that the change of the activation energy corresponding to different film thickness is closely related to the temperature dependence of the electron trapping/detrapping process in polymer thin films, and is determined by both the trapping rate and the detrapping rate. Thinner films need less energy to form a conduction path compared to thicker films. Hence, it leads to smaller activation energy in thinner films, and the activation energy increases with the increase in film thickness. However, a nearly constant value of the activation energy is achieved above a certain range of film thickness, indicating that the trapping rate and detrapping rate is almost equal and eventually the activation energy approaches the value of bulk material.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1289-1291
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• 1994

Dielectric properties of $C_{22}$-Quinolium(TCNQ) Langmuir-Blodgett (LB) films were studied as a function of frequency(10Hz-13MHz) and annealing temperature($20{\sim}240^{\circ}C$). A complex dielectric constant ${\epsilon}^*={\epsilon}'-i{\epsilon}"$, in general, shows the frequency dependence of orientational polarization in the measured frequency range. A dielectric permittivity ${\epsilon}'$ at 10Hz is around 8.2 and decreases very slowly as the frequency increases up to 1 MHz, and then suddenly drops above this frequency, while a dielectric loss factor ${\epsilon}"$ reaches a maximum near 1 MHz. Its annealing temperature dependence at 10Hz shows that ${\epsilon}'$ and ${\epsilon}"$ increase as the temperature increases upto $180^{\circ}C$, even though there is a little drop near $120{\sim}160^{\circ}C$. Both ${\epsilon}'$ and ${\epsilon}"$ drop quickly above $180^{\circ}C$. which may be thought of a destruction of the LB films. Another fact of the annealing temperature dependence of the dielectric constant is an occurrence of the new dielectric dispersion below 100Hz. This low frequency dispersion is getting clear above $80^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.31-36
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• 1997

The effects of 0 to 10mol% excess MgO addition on the microstructure and dielectric properties in 30Pb(Mg1/3Nb2/3)O3-20PbTiO3-50Pb(Mg1/2W1/2)O3 ternary system were investigated. Samples were prepared by mixed oxide and precursor methods to compare the role of excess MgO. Excess MgO enhanced grain growth and increased dielectric constant. The dielectric constant and tesmperature dependence of dielectric constant of the sample sintered at 100$0^{\circ}C$ with 5mol% MgO were above 5,000 and +25% to -50% from - 55$^{\circ}C$ to 1$25^{\circ}C$, respectively. For these specimens the phases percent were mainly perovskite and Pb2WO5, which was confirmed by XRD analysis. Also the amount of cubic pyrochlore Pb3Nb4O13 and PbWO4 were de-creased with sintering temperature and MgO addition. BSE image showed the chemical inhomogeneous dis-tribution. Crystal phase formed at each sintering temperature and the chemical inhomogeneous distribution caused the decrease of the temperature dependence of dielectric constant.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.11
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• pp.526-530
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• 2002

The $(Sr_{0.9}Ca_{0.1})TiO_3(SCT)$ thin films were deposited on Pt-coated electrode (Pt/TiN/$SiO_2$/Si) using RF sputtering method. The composition of SCT thin film deposited on Si substrate at room temperature is close to stoichiometry(1.081 in A/B ratio). The maximum dielectric constant of SCT thin film was obtained by ammealing at $600^{\cric}C$. The temperature dependence of dielectric loss showed a value within 0.02 in temperature ranges of -80 ${\sim}$ +90$^{\circ}C$. The capacitance characteristics showed a stable value within ${\pm}$4%. The drastic decrease of dielectric constant and increase of dielectric loss in SCT thin films was observed at the frequency above 200kHz.

• 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 Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.129-132
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• 1992

Rutile was among the first dielectric materials used. However, rutile exhibits a very high temperature coefficient of capacitance (about -750[ppm/$^{\circ}C$]) which resticts its practical application. Since this first use of titania, other materials have also been studied with the object of decreasing the temperature dependence whilst retaining favorable dielectric loss, Q, and relative permittivity. The temperature coefficient of temperature compensation capacitor is +100~750[ppm/$^{\circ}C$], dielectric constant 10~150. Low loss ceramics with dielectric constants in the 10～150 range also found application. Recently, their applications are extended in EMI filter and dielectric materials for microwave. There temperature coefficient of dielectric materials approaches 0[ppm/$^{\circ}C$]. The dielectric preperties of zirconia titanate ceramics prepared by addition of $Ta_2O_{5}$ were investigated.

• 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.

• Journal of the Korean Ceramic Society
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• v.32 no.10
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• pp.1111-1116
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• 1995

To use dielectric material of high power multilayer capacitor, the composition of the commercial CaTiO3 was changed to decrease the sintering temperature, and the physical and electrical properties were investigated. Series of experiments showed that CaTiO3 with sintering additives had the highest density, the highest shrinkage, the lowest dielectric constant, the lowest loss factor, and the lowest temperature coefficient of capacitance (TCC). These properties had the constant values at sintering temperature of above 120$0^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.7-7
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• 2010

The SBN thin films were deposited at substrate temperature of 300[$^{\circ}C$] on Pt-coated electrode (Pt/Ti/$SiO_2$/Si(100)) using RF sputtering method. The grain and crystallinity of SBN thin films were increased with the increase of annealing temperature. The dielectric constant(150) of SBN thin film was obtained by annealing temperature above 750[$^{\circ}C$]. The frequency dependence of dielectric loss showed a value within 0.03 in frequency ranges of 1~1000[kHz].