• 한국안전학회지
• /
• 제9권1호
• /
• pp.48-55
• /
• 1994

In this paper, It is studied that the variation of the dielectric absorption of the specimen according to the change with $^{60}$ Co-${\gamma}$ ray irradiation dose of the influence of temperature and applied voltage. In order to investigate the effect of irradiated oriented polypropylene film, we have observed dielectric properties within the temporature range of 30~130 ($^{\circ}C$) and voltage range of 100~250 (V). As for the dependency of temperature by tan $\delta$, the $\alpha$ peak which appears at high temperature increases accordingly to the increment of irradiation dose which is contributed by the crystal region and moves towards the high temperature. The $\beta$ peak which appears the orientation by dipoles and molecular motions in the amorphous region at low temperature. For the dependency of voltage by tan $\delta$ at low temperature, the peak of the tan $\delta$ shifts accordingly to the increment of irradiation dose towards the high temperature region.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
• /
• pp.642-645
• /
• 2002

Microwave dielectric properties of $ZnWO_4$ ceramic were investigated with calcination and sintering temperatures. The dielectric properties required for such application are high dielectric constant$(\varepsilon_r)$, high $Q{\times}f_o$ value and low temperature coefficient of resonant frequency$(\tau_f)$. These requirement correspond to necessities for size reduction, excellent frequency selectivity, good temperature stability of devices. $ZnWO_4$ ceramics could be sintered at low $1075^{\circ}C$, which was comparatively low temperature for microwave dielectrics. As a result, $ZnWO_4$ showed the dielectric constant of 13, quality factor($Q{\times}f_o$ value) of 22000 and 'temperature coefficient of resonant frequency$(\tau_f)$ of $-65{\pm}5ppm/^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
• /
• pp.439-442
• /
• 2004

The effects of sintering additives on the low-temperature sintering and microwave dielectric properties of $Mg_4Nb_2O_9$ dielectric ceramics were studied. When $3{\sim}20wt%$ of $0.242Bi_2O_3-0.758V_2O_5$ was added, the sintering temperature decreased from $1100{\sim}1300^{\circ}C$ to $950^{\circ}C$ and high density was obtained. When $Mg_4Nb_2O_9$ was sintered at $950^{\circ}C$ with 10wt% of sintering additive, the microwave dielectric properties of $Q{\times}f_0\;=\;80.035GHz,\;\epsilon_r\;=\;13.3\;and\;\tau_f\;=\;-12.9\;ppm/^{\circ}C$ were obtained.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제49권11호
• /
• pp.603-608
• /
• 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.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.309-309
• /
• 2007

The LTCCs (low-temperature co-fired ceramics) are very important for electronic industry to build smaller RF modules and to fulfill the necessity for miniaturization of devices in wireless communication industry. The dielectric materials with sintering temperature $T_{sint}$<$900^{\circ}C$ are required. In this study, we investigated with glass-ceramic composition, which was crystallized with two crystals. The microstructure, crystal phases, thermal and mechanical properties, and dielectric properties of the composites were investigated using FE-SEM, XRD, TG-DTA, 4-point bending strength test and LCR measurement. The starting temperature for densification of a sintered body was at $779{\sim}844^{\circ}C$ and the glass frits were formatted to the crystal phases, $CaAl_2Si_2O_8$(anorthite) and $CaMgSi_O_6$(diopside), at sintering temperature. The sintered bodies exhibited applicable dielectric properties, namely 6-9 for ${\varepsilon}_r$. The results suggest that the glass-ceramic composite would be potentially possible to application of low dielectric L TCC materials.

• 한국식품과학회지
• /
• 제28권3호
• /
• pp.470-474
• /
• 1996

The dielectric properties, dielectric constant (${\varepsilon}‘$) and loss factor (${\varepsilon}’$), of skin and pulp of fresh ginseng were measured from $25^{\circ}C$ to $67^{\circ}C$ using an open-ended coaxial probe technique for 915 MHz and 2450 MHz. Pulp and skin had dielectric constant of $30{\sim}64$ and loss factor between 10 and 20, each variable having a respective frequency dependence typical of materials with high water content. Although the loss factor was nearly constant, the dielectric constant increased as moisture content increased. The dielectric constant of ginseng pulp increased as temperature increased (temperature ${\leq}56^{\circ}C$), but any significant differences were not found in skin dielectric properties. Penetration depth for fresh ginseng were about 2 cm at 91.5 MHz and 1cm at 2450 MHz.

• Applied Science and Convergence Technology
• /
• 제24권6호
• /
• pp.224-227
• /
• 2015

Ferroelectric $Pb_2(Sc,Nb)O_6$ were prepared under two different sintering conditions using the oxide mixing method and the electrical properties were measured. The sintering conditions were $1350^{\circ}C$ for 25 minutes and $1400^{\circ}C$ for 20 minutes. EDX spectroscopy and XRD were used to determine the crystalline characteristic of the $Pb_2(Sc,Nb)O_6$ compositions Pyrochlore phase showed about 2% in all $Pb_2(Sc,Nb)O_6$ specimens. It expands the growth of crystals in samples sintered at $1400^{\circ}C$ than $1350^{\circ}C$, but all samples were the optimal crystallization. The temperature and frequency dependence of the complex dielectric constant and admittance were measured to analyze the electrical properties. The high dielectric constant of the specimens reflects the good stoichiometry and crystallization. The maximum value of the dielectric constant in the two specimens treated with sintering at $1350^{\circ}C$ and $1400^{\circ}C$ were more than 27,000, and the dielectric loss at room temperature is smaller than 0.05. The maximum dielectric constant decreased with increasing frequency, the transition temperature also increased in $Pb_2(Sc,Nb)O_6$ compositions. The admittance and susceptance values reach a peak at all temperatures, and the magnitude of the peak increases with increasing measuring temperature. Strong frequency dependent of maximum admittance, susceptance, dielectric constant and dielectric loss were observed.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 C
• /
• pp.1615-1617
• /
• 1996

In this study, epoxidized bisphenolic resins laminated with glass fiber mat(GFRP) are ivestigated on surface, bulk aspect and dielectric constant(${\varepsilon}'$ and ${\varepsilon}''$) vs. frequency characteristics with temperature. The investigation shows the different characteristics accordig to the attachments of fiber surface, filler content, matrix properties, and the others. Especially, dielectric properties of this sample are highly increased above $100^{\circ}C$ and decreased with the rise of frequency. There is a resonance at the high frequency region ($1MHz{\sim}10MHz$). So, dielectric properties show the shift with frequency and temperature. Dielectric properties of EGL 10 are higher than those of EGL 40 with the frequency. Generally, dielectric properties of EGL 10 are more unstable than those of EGL 40 on the shift of frequency and temperature.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 기술교육위원회 창립총회 및 학술대회 의료기기전시회
• /
• pp.72-75
• /
• 2001

In this paper, the $Sr_{1-x}Ca_{x}TiO_{3}(0{\leq}x{\leq}0.2)$ 2)-based grain boundary layer ceramics were fabricated to measured dielectric properties and voltage-current properties. The sintering temperature and time were $1420\sim1520^{\circ}C$, 4hours, in $N_{2}$ gas, respectively. The structural and the dielectric properties were investigated by SEM, X-ray, HP4194A and K6517. The 2nd phase formed by thermal diffusion from the surface lead to a very high apparent dielectric constant, $\varepsilon_r$ > 50000. X-ray diffraction patterns exhibited cubic structure for all specimens. Increasing content of Ca, the peak intensity were decreased.ﱇﶖ⨀ਆᘍ܀㘱㔮㠹㬅K䍄乍

• Journal of Electrical Engineering and Technology
• /
• 제6권2호
• /
• pp.263-269
• /
• 2011

In this study, the compositions for the microwave dielectric materials were investigated to obtain the improved dielectric properties, the high temperature stability, and the sintering temperature of less than $900^{\circ}C$, which was necessary for cofiring with the internal conductor of silver. In addition, the dielectric sheets were prepared by the tape casting technique, after which the sheets were laminated and sintered. In this process, the optimum ratio of powder and binder, laminating pressure, temperature, and possibility for cofiring with the internal conductor were studied. Finally, multilayer chip treplexer filter for the 800-2,000 MHz range were fabricated, and the frequency characteristics of the triplexer filter were investigated. When the $0.6TiTe_3O_8-0.4MgTiO_3+3wt%SnO+7wt%H_3BO_3$ ceramics were sintered at $820^{\circ}C$ for 0.3 hours, the microwave dielectric properties of the dielectric constant of 29.91, quality factor of 33,000 GHz, and temperature coefficient of resonant frequency of -2.76 ppm/$^{\circ}C$ were obtained. Using the Advanced Design System (ADS) and High Frequency Structure Simulator (HFSS), the multilayer chip triplexer filter acting at the range of 800-2,000 MHz were simulated and manufactured. The manufactured triplexer filter had the excellent frequency properties in the CDAM800, GPS and PCS frequency regions, respectively.