• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.29-34
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• 2006

The effects of $B_2O_3$ addition on the low-temperature sintering behavior and microwave dielectric properties of $(Zn_{0.8}Mg_{0.2})TiO_3$ ceramic system were investigated. Highly dense samples were obtained at the sintering temperatures below $900^{\circ}C$. The $Q{\times}f_o$ values were determined by the microstructures and sintering shrinkages which are affected by the amount of $B_2O_3$ and sintering temperature. Temperature coefficient of resonance frequency($T_f$) changes to a positive value with increasing the amount of $B_2O_3$ due to the increased amount of rutile phase which is one of the reaction products between $(Zn_{0.8}Mg_{0.2})TiO_3$ and $B_2O_3$. For $6.19 moi.{\%}B_2O_3$-added $(Zn_{0.8}Mg_{0.2})TiO_3$ system, it exhibits ${\epsilon}_r$ = 23.5, $Q{\times}f_o$ = 53,000 GHz, and $T_f$ = 0 ppm/$^{\circ}C$ when sintered at $900^{\circ}C$ for 5 h.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.677-680
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• 2003

The effect of $B_2O_3$ addition on the sintering behavior and microwave dielectric properties of $(Zn_{0.8}Mg_{0.2})TiO_3$ ceramic system were investigated. Highly dense samples were obtained at the sintering temperatures below $900^{\circ}C$. Temperature coefficient of resonance frequency(${\tau}_f$) changes to a positive value with increasing the amount of $B_2O_3$ because of the increased amount of rutile phase. The $Q{\times}f_o$ values were determined by the microstructures and sintering shrinkages which are affected by the rutile or second phase. When 6.19 mol.% of $B_2O_3$ added and sintered at $900^{\circ}C$ for 5h, it exhibits ${\epsilon}_r$ =23.5, $Q{\times}f_o$= 67,500 GHz, and ${\tau}f=-1.42ppm/^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.561-565
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• 2002

The effects of sintering additives such as $Bi_2O_3$ and $V_2O_5$ on the microwave dielectric and sintering properties of (Zn, Mg)$TiO_3$ system were investigated. Highly dense samples were obtained for $(Zn_{0.8}Mg_{0.2})TiO_3$ at the sintering temperature range of $870{\sim}900^{\circ}C$ with $Bi_2O_3$ and $V_2O_5$ additions of <1wt.%, respectively. The microwave dielectric properties of $(Zn_{0.8}Mg_{0.2})TiO_3$ with 0.45 wt.% $Bi_2O_3$ and 0.55 wt.% $V_2O_5$ sintered at $900^{\circ}C$ were as follows: $Q{\times}f_o$=56,800 GHz, ${\varepsilon}_r$=22, and ${\tau}_f=-53ppm/^{\circ}C$. In order to improve temperature coefficient of resonant frequency, $TiO_2$ was added to the above system. The optimum amount of $TiO_2$ was 15 mol.% when sintered at $870^{\circ}C$, at which we could obtain following results: $Q{\times}f_o$ = 32,800 GHz, ${\varepsilon}_r$ = 26, and $\tau_f=0ppm/^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.7
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• pp.604-610
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• 2003

The effects of sintering additives such as B $i_2$ $O_3$ and $V_2$ $O_{5}$ on the microwave dielectric and sintering properties of (Z $n_1$$_{-xM}$ $g_{x}$)Ti $O_3$ system were investigated. Highly dense samples were obtained for (Z $n_{0.8}$M $g_{0.2}$)Ti $O_3$ at the sintering temperature range of 870~90$0^{\circ}C$ with B $i_2$ $O_3$ and $V_2$ $O_{5}$ additions of 〈1 wt.%, respectively. The microwave dielectric properties of (Z $n_{0.8}$M $g_{0.2}$)Ti $O_3$ with 0.45 wt.%B $i_2$ $O_3$ and 0.55 wt.% $V_2$ $O_{5}$ sintered at 90$0^{\circ}C$ were as follows : Q$\times$ $f_{o}$ = 50,800 GHz, $\varepsilon$$_{r}$ = 22, and $\tau$$_{f}$ = -53 ppm/$^{\circ}C$. In order to improve temperature coefficient of resonant frequency, Ti $O_2$ was added to the above system. The optimum amount of Ti $O_2$ was 15 moi.% when sintered at 87$0^{\circ}C$, at which we could obtain following results: Q$\times$ $f_{o}$ = 32,800 GHz, $\varepsilon$$_{r}$ = 26, and$\tau$$_{f}$ = 0 ppm/$^{\circ}C$.EX>.EX>.EX>.EX>.EX>.EX>.EX>.

• Transactions on Electrical and Electronic Materials
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• v.8 no.5
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• pp.201-205
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• 2007

Low temperature sintering behavior and microwave dielectric properties of the $BiNbO_{4^-}$ and the $ZnNb_2O_{6^-}zinc$ borosilicate glass(ZBS) systems were investigated with a view to applying the composition to LTCC technology. The addition of $10{\sim}30$ wt% ZBS in both systems ensured successful sintering below $900^{\circ}C$. For the $BiNbO_{4^-}ZBS$ system, the sintering was completed when 15 wt% ZBS was added whereas 25 wt% ZBS was necessary for the $ZnNb_2O_{6^-}zinc$ system. Secondary phase was not observed in the $BiNbO_{4^-}ZBS$ system but a small amount of $ZnNb_2O_6$ with the willemite structure as the secondary phase was observed in the $ZnNb_2O_{6^-}ZBS$ system. In terms of dielectric properties, the application of the $BiNbO_{4^-}$ and the $ZnNb_2O_{6^-}ZBS$ systems sintered at $900^{\circ}C$ to LTCC were shown to be appropriate; $BiNbO_{4^-}15$ wt% ZBS($\varepsilon_r=25,\;Q{\times}f\;value=3,700GHz,\;\tau_f=-32ppm/^{\circ}C$) and $ZnNb_2O_{6^-}25$ wt% ZBS($\varepsilon_r=15.8,\;Q{\times}f\;value=5,400GHz,\;\tau_f=-98ppm/^{\circ}C$).

• Journal of the Korean Ceramic Society
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• v.32 no.6
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• pp.719-725
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• 1995

ZST powders were synthesized by coprecipitation of (Zr4+, Ti4+)-hydroxide in the presence of SnO2 particles. Zn(NO3)2 was used as a sintering additive, and according to the adding sequence, sintering and dielectric properties were investigated. Sintered densities of ZST prepared by adding Zn(NO3)2 before calcination were a little higher than those added after calcination, and dielectric properties of the specimen added by Zn(NO3)2 after calcination were better (sintered at 125$0^{\circ}C$/2 h ; Q$\times$f(GHz)=49, 000, $\varepsilon$r=41) than before calcination (Q$\times$f(GHz)=42, 000, $\varepsilon$r=39.5). Through the observation of TEM, it was identified that the cause was due to the difference of the degree of Zn2+ diffusion into grains. With increasing sintering time from 2 to 8 hrs, grain size was doubled and dielectric properties were somewhat deteriorated.

• Journal of the Korean Ceramic Society
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• v.43 no.1 s.284
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• pp.55-61
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• 2006

The microwave dielectric properties and low temperature sintering of $Ca[Ti_{1-x}(Ni_{1/3}Nb_{2/3})_x]O_3$ system were investigated at the sintering temperature $1,200\~1,350^{\circ}C$. The density and quality factors $(Q{\times}f)$ increased while dielectric constants slightly decreased with the decrease of Ti. The dielectric constant, quality factor, and temperature coefficient of resonance frequency $(\tau_f)$ were 64, 17,000 GHz, and $-9.1\;ppm/^{\circ}C$ respectively, when $CaTi_{1/2}(Ni_{1/3}Nb_{2/3})_{1/2}O_3$ ceramics were sintered at $1,300^{\circ}C$ for 4 h. $2Li_2O-B_2O_3$ was added to $CaTi_{1/2}(Ni_{1/3}Nb_{2/3})_{1/2}O_3$ to decrease the sintering temperature for LTCC application. The microwave dielectric properties of the samples sintered at $925^{\circ}C$ for 2 h with the addition of $6\;wt\%\;2Li_2O-B_2O_3$ were $\varepsilon_r=48.7,\;Q{\times}f=8,460\;GHz$, and $\tau_f=+5.6ppm/^{\circ}C$. Compatibility test of the composition with silver electrode shows no reaction with silver electrode, implying the feasibility as a high-K LTCC material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.64-67
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• 1997

Microwave dielectric properties of A1$_2$O$_3$ ceramics resonator were investigated with impurity addition. Increasing the contents of Bi$_2$O$_3$Q-value and Q $\times$ f were increased. In the specimen with the content of Bi$_2$O$_3$(0.3wt%), dielectric constant, quality factor and temperature coefficient of resonant frequency(TCRF, $\tau$$_{f}$) had a good values of 10.76,23,253(at 9.68[GHz]) and -39.09(ppm/$^{\circ}C$), respectively. The TCRF value was decreased with MnO$_2$ and increased with Sm$_2$O$_3$. La$_2$O$_3$.>.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.252-252
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• 2007

$Al_2O_3-TiO_2$(AT)ceramics shows great promise as a dielectric material for millimeter-wave use. The sintering temperature of AT ceramics was approximately $1450^{\circ}C$ and decreased to $900^{\circ}C$ with the addition of BaCu(B2O5) (BCB) ceramic powder. The presence, of the liquid phase was responsible for the decrease of the sintering temperature. The liquid phase is considered to have a composition similar to the BaO-deficient BCB. The Q-value initially increased with the addition of BCB, but decreased considerably when a large amount of BCB was added, because of the presence of the liquid phase. Good microwave dielectric properties of $Q{\times}f\;=\;16,200\;GHz$, ${\varepsilon}_r\;=\;9$ and ${\tau}_f\;=\;-4\;ppm/^{\circ}C$ were obtained for the 20.0 mol% BCB-added AT ceramics sintered at $900^{\circ}C$ for 2 h.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.131-134
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• 2003

[ $ZnWO_4$ ] shows excellent frequency selectivity due to its high quality factor($Q{\times}f$) at microwave frequencies. However, in order to use $ZnWO_4$ as multilayered wireless communication components, its other properties such as sintering temperature($1050^{\circ}C$), ${\tau}_f$ ($-70ppm/^{\circ}C$) and ${\varepsilon}_r(15.5)$ should be modified. In present study, $TiO_2$ and LiF were used to improve the microwave dielectric and sintering properties of $ZnWO_4$. $TiO_2$ additions to $ZnWO_4$ changed ${\tau}_f$ from negative to positive value, and also increased ${\varepsilon}_r$ due to its high ${\tau}_f$ ($+400ppm/^{\circ}C$) and ${\varepsilon}_r$(100). At 20 mol% $TiO_2$ addition, ${\tau}_f$ was controlled to near zero $ppm/^{\circ}C$ with ${\varepsilon}_r=19.4$ and $Q{\times}f=50000GHz$. However, the sintering temperature was still high to $1100^{\circ}C$. LiF addition to the $ZnWO_4+TiO_2$ mixture was greatly reduced the sintering temperature from $1100^{\circ}C$ to $850^{\circ}C$ due to liquid phase formation. Also LiF addition decreased the ${\tau}_f$ value due to its high negative ${\tau}_f$ value. Therefore, by controlling the $TiO_2$ and LiF amount, temperature stable LTCC material in the $ZnWO_4$-TiO_2-LiF$ system could be fabricated.