• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.322-332
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• 2022

Energy storage capacitors based on dielectric ceramics with superior polarization properties and dielectric constant can provide much higher output power density due to their very fast energy charging/discharging rates, which are particularly suitable for operating pulsed-power devices. For an outstanding energy storage performance of dielectric capacitor, a large recoverable energy density could be derived by introducing a slim polarization-electric field hysteresis loop into dielectric materials by various technical approaches. Many research teams have explored various dielectric capacitor technologies to demonstrate high output power density and ultrafast charging/discharging behavior. This article reviews the recent research progress in high-performance dielectric capacitors for pulsed-power electronic applications.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.7
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• pp.597-601
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• 2002

In this study, the structural, dielectric and piezoelectric properties of $Pb[(Ni_{1/3}Nb_{2/3})_x-(Mn_{1/3}Nb_{2/3})_{0.09-x}-(Zn_{0.505}Ti_{0.495)_0.91]O_3$ (x=0, 0.01, 0.02, 0.03, 0.04, 0.05) system ceramics were investigated to develop the composition ceramics for piezoelectric transformer. All the specimens were sintered at $1250^{\circ}C$ and its physical properties were measured, and the results are as follows : With increasing PNN substitution for PMN-PZT system, dielectric constant was increased and electro-mechanical coupling factor($k_p$) was increased to 0.62 at 5 mol% while mechanical quality factor(Qm) was decreased.

• 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.

• Journal of the Korean institute of surface engineering
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• v.36 no.5
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• pp.413-417
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• 2003

The effect of 0-0.7 ㏖% addition of $Cr_2$$O_3$on the dielectric, pyroelectric, and piezoelectric properties were studied in the (Mg$0.7Pb_{1}$$3/Nb_{2}$3/)$O_3$-$0.3PbTiO_3$(0.7PMN-0.3PT) ceramics with composition near the morphotropic phase boundary. The dielectric constant and loss of the ceramics samples were measured as a function of temperature at various frequencies (0.1-100 KHz). The pyroelectric coefficient was measured by using the Byer-Roundy method as a function of temperature. Dielectric, pyroelectric, and piezoelectric constant achieved the maximum values of 0.4 ㏖% $Cr_2$$O_3$The transition temperature is continuously shifted to lower temperature with an increase of a small amount of $Cr_2$$O_3$.

• The Korean Journal of Ceramics
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• v.2 no.2
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• pp.111-113
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• 1996

Dielectric properties at microwave frequency region of the five-layered compound $Ba_5Nb_4O_{15}$ prepared by the conventional solid state reaction method were investigated. $Ba_5Nb_4O_{15}$ has excellent microwave dielectric characteristics; ${\varepsilon}_r$=38, Q=7500 at 10 GHz, and ${\tau}_l$=+50 ppm/K. Since this compound has a high dielectric constant, high Q and sufficiently stable characteristics, it is useful for the applications at microwave frequencies.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.3
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• pp.159-163
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• 2016

In this paper, in order to develop optimum composition ceramics with excellent piezoelectric properties, $(Na_{0.525}K_{0.443}Li_{0.037})(Nb_{0.823}Sb_{0.08}Ta_{0.037})O_3+0.3wt%Bi_2O_3+0.4wt%Fe_2O_3$ lead-free piezoelectric ceramics were synthesized by conventional soild-state method. The calcination temperature of columbite precursors were fabricated at temperature range from $950^{\circ}C$ to $1,150^{\circ}C$ and sintering aids with low melting point were added to densify these ceramics. Effect of calcination temperature on dielectric and piezoelectric properties of ceramics were investigated. the ceramics with B-site columbite precursors at temperature of $1,100^{\circ}C$ obtained the optimal values of $d_{33}=272$ [pC/N], $k_p=0.51$, $Q_m=102$, ${\varepsilon}_r=978$.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1589-1591
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• 2003

The microwave dielectric properties of $TiTe_3O_8-CaF_2$ ceramics were investigated. All sample of $TiTe_3O_8-CaF_2$ ceramics were prepared by the conventional mixed oxide method, and sintered in the temperature of $730^{\circ}C{\sim}750^{\circ}C$. The structural properties of $TiTe_3O_8-CaF_2$ ceramics were investigated by the X-ray diffractor meter. According to the X-ray diffraction patterns of $TiTe_3O_8-CaF_2$ ceramics, the major phase of the cubic $TiTe_3O_8$ were presented. In the case of $1molTiTe_3O_8-0.1molCaF_2$ ceramics sintered at $740^{\circ}C$ for 5hr., the bulk density, dielectric constant, quality factor were $2.8g/cm^3$, 39.1, 36.100GHz, respectively.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1541-1543
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• 2003

The microwave dielectric properties of $0.6Mg_4Ta_2O_9-0.4TiO_2$ ceramics were investigated. All sample of $0.6Mg_4Ta_2O_9-0.4TiO_2$ ceramics were prepared by the conventional mixed oxide method, and sintered in the temperature of $1350^{\circ}C{\sim}1450^{\circ}C$. The structural properties of $0.6Mg_4Ta_2O_9-0.4TiO_2$ ceramics were investigated by the X-ray diffraction meter. According to the X-ray diffraction patterns of $0.6Mg_4Ta_2O_9-0.4TiO_2$ ceramics, the major phase of the hexagonal $0.6Mg_4Ta_2O_9-0.4TiO_2$ were presented, In the case of $0.6Mg_4Ta_2O_9-0.4TiO_2$ ceramics sintered at $1400^{\circ}C$ for 5hr., the dielectric constant, quality factor and temperature coefficient of resonant frequency were 12.19, 109.411GHz, -17.21ppm/$^{\circ}C$, respectively.

• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.965-973
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• 1999