• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.752-754
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• 1998

$Ba(Mg_{(1-x)}Co_x)_{1/3}(Ta_{(1-x)}Nb_x)_{2/3}O_3$ ($x=0.3{\sim}0.6$) ceramics were prepared by the conventional mixed oxide method. The sintering temperature and time were of $1400{\sim}1575[^{\circ}C]$,5[hr.] respectively. The structural and microwave dielectric Properties were investigated with composition ratio and sintering temperature. And then the application for the microwave dielectric resonator was investigated.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.320-323
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• 1997

The microwave dielectric properties of X Ba0-$0.15(Nd_{0.87}Bi_{0.13})_2O_3$-(0.85-X) $TiO_2$ ($X=0.13{\sim}0.17$) and 0.16Ba0-$0.15(Bi_xNd_{1-x})_2O_3-0.69TiO_2$ ($X=0.10{\sim}0.16$) ceramics were investigated. Dielectric constant, quality factor and temperature coefficient of resonant frequency of 0.16Ba0-$0.15(Nd_{0.87}Bi_{0.13})_2O_3-0.69TiO_2$ ceramics sintered at $1320^{\circ}C$ for 2 hours were 89.2, 1920(at 4GHz) and 5.2ppm/$^{\circ}C$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.335-338
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• 1998

The effect of glass flit addition on microwave dielectric properties of BaTiO$_3$-3TiO$_2$ ceramic was studied. Addition of glass frit to this system obtained sintered sample below sintering temperature 105$0^{\circ}C$. At BaTiO$_3$-3TiO$_2$+ g1ass frit 3wt% + BaWO$_4$6 wt%m, this ceramic showed excellent microwave properties of dielectric constant 34, Q$\times$f 8,100, temperature coefficient of resonant frequency 4 ppm/$^{\circ}C$ .

• Journal of Electrical Engineering and Technology
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• v.1 no.1
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• pp.120-126
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• 2006

Ferroelectric materials have been widely investigated for high density dynamic random access memories, opto-electrics, and tunable microwave devices due to their properties. In this study, we have investigated the dielectric properties of Ti doped $K(Ta,\;Nb)O_3$ thin films. By doping Ti Into the $K(Ta,Nb)O_3$ system, Ti with a valence value of +4 will substitute Ta or Nb ions with a valence value of +5. This substitution will introduce an acceptor state. Therefore, this introduced acceptor state will reduce dielectric loss by trapping electrons. Using 3% Ti-doped $K(Ta,Nb)O_3\;targets,\;K(Ta,Nb)O_3$:Ti films were grown in MgO(001) crystals using pulsed laser deposition. First, growth conditions were optimized. A reduction in the loss tangent was observed for Ti-doped $K(Ta,Nb)O_3$ relative to undoped films, although a reduction in tunability is also seen. The crystallinity, morphology, and tunability of $K(Ta,Nb)O_3$:Ti films are reported.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.139-144
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• 2016

The dependence of the microwave dielectric properties of the glass-ceramic composite $0.9CaMgSi_2O_6-0.1MgSiO_3$ on the crystallization behaviour was investigated as functions of the $TiO_2$ content and heat-treatment temperature. The crystallization behaviour of the specimens was evaluated via a combination of the Rietveld and reference-intensity ratio methods. For specimens with a $TiO_2$ content of up to 1 wt.%, a monoclinic diopside phase was formed, whereas a secondary $TiO_2$ phase was formed with further increases in the $TiO_2$ content. The quality factor (Qf) of the specimens was strongly dependent on the degree of crystallization. The highest Qf value was obtained with a $TiO_2$ content of 0.5 wt.%, which was improved by increasing the heat-treatment temperature. The dielectric constant (K) was affected by the size of the crystallites and the $TiO_2$ content. The temperature coefficient of the resonant frequency (TCF) was nearly constant for all of the specimens, regardless of the $TiO_2$ content or heattreatment temperature.

• Journal of the Korean Ceramic Society
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• v.32 no.5
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• pp.535-542
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• 1995

The effect of sintering temperature, sintering time and forming pressure on microwave dielectric properties of (Zr1-xSnx)TiO4 ceramics containing 1.0wt% B2O3, 0.3 wt% La2O3 and 1.0wt% NiTa2O6 was investigated using the response surface methodology. The optimum values of processing variables were determined based on the reproducibility. The optimum values of the dielectric constant of >35. Q.f0 of >55000 and $\tau$f=$\pm$5 ppm/$^{\circ}C$ could be obtained when the sample was pressed at 500~600kg/$\textrm{cm}^2$ and sintered at 1500~155$0^{\circ}C$ for 2~3 hrs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.279-282
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• 2003

For the millimeter-wave dielectrics, Forsterite-based ceramics were produced. Pure forsterite ceramics($Mg_2SiO_4$) shows porous micro-structure and very low Q*f values, which is not suitable for the dielectrics for the millimeter-wave band. Several sintering aids including $Al_2O_3$, $Li_2CO_3$, $Li_2SiO_4$, were added to the forsterite ceramics in order to produce dense low-loss dielectrics. Among these additives, $Li_2CO_3$ is the most effective sintering aids. Several sub-components including NiO, ZnO, $SnO_2$, $TiO_2$, were added to enhance the microwave dielectric properties. $TiO_2$ is the most effective additive to enhance the dielectric properties at microwave bands. The simultaneous addition of $TiO_2$ and $Li_2CO_3$ increases Q*f value over 170,000, which can be used as dielectrics in millimeter-wave bands.

• Journal of the Korean Ceramic Society
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• v.41 no.8
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• pp.633-636
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• 2004

The sintering behavior, microstructure and microwave dielectric properties of Ca $Ti_{0.5}$F $e_{0.25}$N $b_{0.25}$ $O_3$ with CuO have been investigated. Among the range of additions, 3 wt％ CuO was observed to perform most satisfactory for acting as a sintering aid. The dielectric properties were found to strongly depend on the sintered densities. The dielectric constant increased with sintering temperatures, while the Q${\times}$ $f_{0}$ value affected by second phase. For Ca $Ti_{0.5}$F $e_{0.25}$N $b_{0.25}$ $O_3$ with 3 wt％ CuO sintered at 100$0^{\circ}C$ for 2 h, the dielectric properties with an $\varepsilon$$_{r}$ value of 56, a Q${\times}$ $f_{0}$ value of 3,500 GHz and a $\tau$$_{f}$ value of 10 ppm/$^{\circ}C$ were obtained and suggested for practical applications.cations.ons.ons.ons.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1719-1723
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• 2014

In this study, the microwave dielectric properties of nano spheroidization glass powders added $Ba(Zn_{1/3}Ta_{2/3})O_3$ ceramics prepared by solid state reaction have been investigated. Adding $(Ba_{0.4}Ca_{0.6})SiO_3$ nano spheroidization glass powders could effectively promote the densification even in the case of decreasing the sintering temperature. When the glass frit is 0.3 wt% and sintering is carried out at a temperature of $1500^{\circ}C$ for 6 hr, a temperature stable microwave dielectric ceramic could be obtained, which has a dielectric constant (${\varepsilon}_r$) of 30.2, a quality factor ($Q{\times}f_0$) of 124,000 GHz and a temperature coefficient of resonance frequency (${\tau}_f$) of $2ppm/^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.342-343
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• 2005

In this study,. the microwave dielectric properties of the $0.6TiTe_3O_8-0.4CaWO_4$ ceramics with sintering temperature were investigated for LTCC application. According to the X-ray diffraction patterns, the $0.6TiTe_3O_8-0.4CaWO_4$ ceramics had columbite structure of the $TiTe_3O_8$ phase and scheelite structure of the $CaWO_4$ phase. Increasing the sintering temperature, the bulk density, the dielectric constant and the quality factor of the $0.6TiTe_3O_8-0.4CaWO_4$ ceramics were increased. In the case of the $0.6TiTe_3O_8-0.4CaWO_4$ ceramics sintered at $810^{\circ}C$, the bulk density, the dielectric constant and the quality factor were 5.72$g/cm^2$, 33.6, 22,013GHz respectively.