• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.4
• /
• pp.396-403
• /
• 2004

The dielectric properties of Y-ray irradiated and thermally aged polyetheretherketone (PEEK) have been investigated. Results of the temperature dependency of dielectric properties indicated that the glass transition temperature of aged PEEK increased as radiative and thermal ageing. The frequency dependency of dielectric properties implied that the magnitude of radiation and thermal induced dipoles, ions increased as radiative and thermal ageing. The values of relaxation intensity calculated using Cole-Cole's circular arc can be useful for evaluation of degradation level of PEEK.

• The Korean Journal of Ceramics
• /
• v.1 no.1
• /
• pp.13-20
• /
• 1995

Effects of thermal annealing on the dielectric/piezoelectric properties of $Pb(Zn, Mg)_{1/3}Nb_{2/3}O_3-PbTiO_3$ ceramics (PZMNPT) with Zn/Mg=6/4) were examined across the rhombohedral/tetragonal morphotropic phase boundary (MPB). Both the relative dielectric permittivity ($\varepsilon$r)and the piezoelectric constant($d_33$)/electromechanical coupling constant ($k_p$)were increased by thermal annealing ($800^{\circ}$~$900^{\circ}C$) after sintering at $1150^{\circ}C$ for 1 hr. Based on the dielectric analysis using the series mixing model and the concept of a random distribution of the local Curie points, the observed improvements in the dielectric and piezoelectric properties of PZMN-PT were interpreted in terms of the elimination of PbO-rich amorphous intergranular layers(~1nm) induced by thermal annealing. A concrete evidence of the presence of amorphous grain-boundary layers in the unannealed (as-sintered) specimen was obtained by examining the structure of intergranular region using a TEM.

• Journal of the Korea Safety Management & Science
• /
• v.4 no.4
• /
• pp.137-146
• /
• 2002

In order to investigate the effect of irradiation by $^{60}Co-\gamma$rays as well as the e thermal treatment on the dielectric deterioration in ethylene propylene rubber, insulating material for electric cables used in atomic power plants, charging discharging current, residual built- up voltage and dielectric properties are measu discussed in this study. Variance in the characteristic of relative dielectric constant as a function of tem was observed in relatively high dose of irradiation. Since glass transition tem appeared at tens of degree Celsius below zero, the characteristic is attributed orientation polarization. Dielectric loss is generally increased, with increasing d irradiation in the characteristic of dielectric loss as a function of temperature, No d loss by thermal treatment was observed. Dielectric resistance decreases with increa of irradiation in the characteristic of charging current as a function of temperature be considered that dielectric resistance seems to be recovered by thermal treatm characteristic of discharging current as a function of time in the specimen less ir become similar to that of the unirradiated, when thermal treated. A peak is shown residual built- up voltage as a function of time, and the corresponding time of the shorten as increasing dose of irradiation. It is also observed that the corresponding the peak is lengthened by thermal treatment.

• Journal of the Korean Ceramic Society
• /
• v.32 no.8
• /
• pp.881-892
• /
• 1995

Sol-Gel derived ferroelectric PZT thin films were fabricated on ITO/Glass substrate. Two kinds of rapid thermal annealing methods, R-I (six times of intermediate and final annealing) and R-II (one final annealing after six times of intermediate annealing) were used for preparation of multi-coated PZT thin films. 2500$\AA$-thick PZT thin films were obtained by the R-I and R-II methods and characterized by microstructure and dielectric properties. In case of using R-II, the microstructure was finer than that of R-I and there was no distinguishable difference in dielectric properties of PZT thin films between the R-I and R-II methods. But dielectric properties were enhanced by increasing perovskite phase fraction with increasing annealing temperature. Measured dielectric constant of PZT thin film annealed at 62$0^{\circ}C$ using the R-I method was 256 at 1kHz. Its remanant polarization (Pr) and coercive field (Ec) were 14.4$\mu$C/$\textrm{cm}^2$ and 64kV/cm, respectively.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.4
• /
• pp.1700-1711
• /
• 2015

In the last decade it has been witnessed significant developments in the area of nano particles and nano scale fillers on electrical, thermal, and mechanical properties of polymeric materials such as resins, varnishes, enamel and bakelites. The electric and thermal properties were more important in the electrical equipments for both steady state and transient state conditions. This paper deals with the characterization of the electric and thermal properties of the pure varnish and zirconia (ZrO₂) filler mixed varnish. The electric properties such as dielectric loss (tan δ), dielectric constant (ε), dielectric strength and partial discharge voltage were analyzed and detailed for different samples. It was observed that zirconia nano filler mixed varnish has the superior dielectric and thermal properties when compared to those of standard varnish. It has shown that at power frequency the 1wt% nano composite sample has the higher permittivity value when compared to other samples. It has been examined that the 1wt% sample was having higher inception and extinction voltages when compared to other samples. It has been observed that 1wt% sample has higher dielectric strength when compared with other samples. There has been an improvement of thermal property by adding few weight percent of zirconia nano fillers. There was not much variation in glass transition among the nano mixed composites. The weight loss was improved at 1wt% of the zirconia nano fillers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.34 no.5
• /
• pp.337-341
• /
• 2021

Phase evolution, thermal and microwave dielectric properties of cordierite-Al₂O₃ composite were investigated. As the content of Al₂O₃ increased, mullite, sapphirine, and spinel were formed as secondary phases, implying that cordierite may be decomposed by the reaction with Al₂O₃. All sintered specimens exhibited dense microstructures. The densification occurred through liquid phase sintering. As the content of Al₂O₃ increased, the thermal expansion coefficient and the dielectric constant increased, whereas the quality factor decreased. The thermal expansion coefficient, the dielectric constant, and the quality factor of the 90 wt% cordierite 10 wt% Al₂O₃ composite sintered at 1,425℃ were 2.9×10^-6 K^-1, 5.1, and 34,844 GHz, respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.11
• /
• pp.539-543
• /
• 2001

ln this paper, the $Sr_{l-x}Ca_xTiO_3(0\leqx\leq0.2)-based$ grain boundary layer ceramics were fabricated to measure dielectric properties with the sintering temperature and the thermal treatment time. The sintering temperature and time were $1420~15206{\circ}C$, 4hours, and the thermal treatment temperature and time of the specimen were $l150^{\circ}C$, 1, 2, 3hours, respectively. The structural and the dielectric properties were investigated by SEM, X-ray, HP4194A and K6517. The average grain size was increased with increasing the sintering temperature, but it decreased up to 15mo1% with increasing content of Ca. X-ray diffraction analysis results showed that all specimens were the cubic structure, and the main peaks were moved to right and the lattice constant were decreased with increasing content of Ca. The appropriate thermal treatment time and temperature of CuO to obtain dielectric properties of $\varepsilon_r>50000,\; tan \delta<0.05\; and \;\DeltaC<\pm10%$ were 2hrs and $l150^{\circ}C$, respectively.

• Transactions on Electrical and Electronic Materials
• /
• v.3 no.1
• /
• pp.42-45
• /
• 2002

Properties of lead zirconate titanate ferroelectric thin films prepared by rapid thermal annealing/direct insertion thermal annealing were investigated. The remnant polarization (Pr), saturation polarization (Ps), and coercive force (Ec) of typical samples annealed by rapid thermal annealing (RTA) are about 13.7 $\mu$ C/cm$^2$, 27.1 $\mu$C/cm$^2$, and 55.6 kV/cm, respectively. The dielectric constant of the sample is about 786, the dielectric loss tangent is about 2.4% at 1 kHz. Furthermore, ferroelectric, conduction, and piezoelectric properties of the thin films annealed by RTA process and the direct insertion thermal annealing (DITA) process were compared. The influence of temperature in the dry process on the above properties was also investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.220-221
• /
• 2007

Recently, imprint lithography have received significant attention due to an alternative technology for photolithography on high performance microelectronic devices. In this work, we investigated thermal stabilities and dynamic mechanical properties of dielectric materials for thermal imprint lithography. Curing behaviours, thermal stabilities, and dynamic mechanical properties of the dielectric materials cured with various curing agent and spherical filler were studied using dynamic differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), rheometer and universal test machine(UTM).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.207-208
• /
• 2007

Recently, high performance microelectronic devices are designed in multi-layer structure in order to make dense wiring of metal conductors in compact size. Imprint lithography have received significant attention due to an alternative technology for photolithography on such devices. In this work, we synthesized dielectric composite materials based on epoxy resin, and investigated their thermal stabilities and dynamic mechanical properties for thermal imprint lithography. In order to enhance the mechanical properties and toughness of dielectric material, various modified polyetherimide(PEI) was applied in the resin system. Curing behaviours, thermal stabilities, and dynamic mechanical properties of the dielectric materials cured with various conditions were studied using dynamic differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), and Universal Test Method (INSTRON).