• Journal of Sensor Science and Technology
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• v.6 no.5
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• pp.392-399
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• 1997

In this study, the effect of the sintering temperature on the dielectric and piezoelectric properties of 0.5 wt% $MnO_{2}$-doped $0.125Pb(Mg_{1/2}Nb_{2/3})O_{3}-0.435PbTiO_{3}-0.44PbZrO_{3}$ ceramics were investigated aiming at ultrasonic motor applications. From experimental result, it was found that the optimal sintering temperature condition was at $1270^{\circ}C$. The sample sintered at $1270^{\circ}C$ had density of $7.72\;g/cm^{3}$, dielectric constant of 570, dielectric loss of 0.82%, remanent polarization of $19.18{\mu}C/cm^{2}$, coercive field of 9.63 kV/cm, electromechanical coupling factor of radial mode of 55.1%, mechanical quality factor of 886. Temperature and frequency dependence of dielectric constant and dielectric loss of the sintered sample at $1270^{\circ}C$ was also investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.18-22
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• 2006

Epitaxial aluminum nitride films on 6H-SiC (0001) were fabricated using reactive RF magnetron sputtering and post-deposition rapid thermal annealing. The electrical properties of AIN films depending on film thickness and measurement temperature have been observed. Full width at half maximum of AIN (0002) was $0.1204^{\circ}$ (about 430 arcsec) X-ray rocking curve results. The equivalent oxide thickness (EOT) of AIN film was estimated as about 10 nm and the leakage current density was within the order of $10^{-8} 4/cm^2$. The dielectric constant of AIN film estimated from the accumulation region of C-V curve measured at $300^{\circ}C$ was 8.3. The dynamic dielectric constant was obtained as 5.1 from J vs. 1/T plots at the temperature ranging from R.T. to $300^{\circ}C$ From above, estimation temperature dependance of the electrical properties of Al/AIN/SiC MIS devices was affirmed and useful data compilation for the reliabilities of SiC MIS is expected.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.396-401
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• 2000

In order to accurately measure the high voltage of 22.9[kV] power distribution lines we investigated the temperature dependence of measuring voltage on the number of stack layers in the voltage measurement system made from single and stack voltage divider capacitors (22, 44, 66 layers, respectively). Temperature coefficient of dielectric constant(TC$\varepsilon_{{\gamma}}$/)of voltage divider capacitors which were fabricated by BaTi $O_3$system ceramics showed the variations from -2.28% to +1.69% in the range of -25[$^{\circ}C$] ~50[$^{\circ}C$]) was decreased with increasing of stack number and the stack element of 66 layers showed the least error of $\pm$0.87%or of $\pm$0.87%.

• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.70-74
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• 2013

Dependence of microwave dielectric properties on the crystallization behaviors of $CaMgSi_2O_6$ (diopside) glass-ceramics was investigated with different heat treatment methods (one and/or two-step). The crystallization behaviors of the specimens, crystallite size and degree of crystallization, were evaluated by differential thermal analysis (DTA), scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis by combined Rietveld and reference intensity ratio (RIR) methods. With an increase in heattreatment temperature, the dielectric constant (K) and the quality factor (Qf) increased due to the increase of the crystallite size and degree of crystallization. The specimens heat-treated by the two-step method had a higher degree of crystallization than the specimens heat-treated by the one-step method, which induced improvement in the quality factor (Qf) of the specimens.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1487-1489
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• 2001

The tantalum oxide($Ta_2O_5$) is an important material for present thin-film capacitor application owing to its high dielectric constant and thermal stability. We report dielectric property of Si(p type)/Pt/$Ta_2O_5$/Ag based MIM structure obtained by RF sputtering and annealed in vacuum environment. We have measured and researched the characteristics of C-F, C-V and EPMA. And we describe parameter dependence on sputtered condition and annealed temperature with dielectric property.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1990.10a
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• pp.65-67
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• 1990

In this study, (0.80-x)Pb($Mg_{1/3}Nb_{2/3}$)$O_3$-$PbTiO_3$-Pb($Ni_\frac{1}{2}W_\frac{1}{2}$)$O_3$ 0.05$\leq$x$\leq$0.20) ceramics were fabricated by the mixed oxide method, the sintering temperature and time were 950∼1200[$^{\circ}C$], 2[hr], respectively. The dielectric and structural properties with composition and sintering temperature were investigated for the application as multilayer ceramic capacitors. Dielectric constant of 0.70PMN-0.2PT-0.10PNW composition with repeated calcination was increased rapidly. Increasing the Pb($Mg_{1/3}Nb_{2/3}$)$O_3$-$PbTiO_3$-Pb($Ni_\frac{1}{2}W_\frac{1}{2}$)$O_3$ contents from 0.05 to 0.20 [mol], phase transition temperature was shifted from 68 to 2[$^{\circ}C$] and dielectric constant was decreased while sintered density was increased. In the specimens containing 0.10, 0.15[mol] of PNW, dielectri constants at room temperature were exhibited the highest values 11199, 10114, respectively. Resistivity of specimens were $10^{10}$ ∼ $10^{12}$($\Omega$.m) and there was no dependence on sintering temperature and composition.

• Journal of the Korean Ceramic Society
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• v.26 no.1
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• pp.43-50
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• 1989

This experiment was conducted to investigate correlation between microstructure and electrical properties according to Zr/Ti mole ratio in Rhombohedral Phase PZT. Domain behavoir was investigated by the change of thermal expansion coefficient. Piezoelectric properties, the temperature dependence of dielectric constant and the change of dielectric constant before and after poling were measured. Crystal structure, the measurement of lattice parameter were carried by X-ray analysis. Domain pattern before and after poling was examined by SEM.

• Journal of the Korean Ceramic Society
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• v.47 no.2
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• pp.163-168
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• 2010

Effects of compositions on the microwave dielectric properties of the MgO-$TiO_2$ system were investigated as a function of the molar ratio of MgO to $TiO_2$ ($0.9{\leq}MgO/TiO_2\;(x){\leq}1.2$). With the compositional changes, secondary phases of $MgTi_2O_5$ and $Mg_2TiO_4$ were also detected along with $MgTiO_3$. Microwave dielectric properties of the specimens were dependent on the types of phases developed in the sintered specimens. A single phase of $MgTiO_3$ showed a dielectric constant (K) of 18.2, a quality factor (Qf) of 198,000 GHz, and a temperature coefficient of resonant frequency (TCF) of $-51\;ppm/^{\circ}C$. However, the dielectric properties of the specimens with a secondary phase of $MgTi_2O_5$ (K=19.9, Qf=48,000 GHz) and/or $Mg_2TiO_4$ (K=15.6, Qf=56,000 GHz) were worsened. Dependence of the microwave dielectric properties on the secondary phase of the MgO-$TiO_2$ system was also discussed in terms of dielectric mixing rules.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.19.1-19.1
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• 2011

Effects of particle size, crystal structures and multilayer structures of $ATiO_3$, $ATa_2O_6$, $ANb_2O_6$, $AWO_4$, and $AMoO_4$ (A=Ni, Mg, Zn, Co) ceramic fillers on the dielectric properties of polystyrene (PS), polypropylene (PP) and polytetrafluoroethylene (PTFE) polymer matrices were investigated at microwave frequencies. The microwave dielectric properties of $ATiO_3$ (ilmenite), $ATa_2O_6$ (tri-rutile), $ANb_2O_6$ (columbite), AWO4 (wolframite), and AMoO4 (wolframite) ceramics were largely dependent on the structural characteristics of oxygen octahedra. The dielectric constant (K) of the composites was increased with the ceramic content. However, the dielectric loss (tan ${\delta}$) of the composites was affected by the type of ceramics and the crystallinity of polymers. For the composites with same amount of ceramics, the K was decreased and the tan ${\delta}$ was increased with the particle size of ceramics. Also, the dielectric properties of the composites were dependent on the multilayer structures with different arrangements. Several theoretical models have been employed to predict the effective dielectric properties of the composites. The frequency dependence of dielectric properties and the temperature coefficient of resonant frequency (TCF) of the composites were also discussed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.5
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• pp.175-182
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• 2022

Rare-earth elements were doped with Mg to enhance the temperature stability of dielectric properties of BaTiO₃ for its application to MLCC (Multi-Layer Ceramic Capacitor). The additives strongly affect both grain growth and densification behaviors during sintering, and hence dielectric properties. The additive effects therefore should be examined in each system with different additives. This study investigated the crystal structure, grain growth and densification behaviors and related variations in dielectric constant with respect to sintering temperature. Dielectric constant appears to be varied with grain size in a temperature range between 1200 and 1300℃, suggesting the importance of grain size control. The temperature dependence of grain size variation was well explained by an established theory correlating the grain growth behavior with grain boundary structure. This accordance provides a basis for sintering technique to control grain growth thus to improve dielectric constant in rare-earth doped BaTiO₃.