• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.6
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• pp.538-542
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• 2005

The structural and microwave dielectric properties of $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics with sintering temperature were investigated. All the sample of the $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics were prepared by conventional miked oxide method and the sintering temperature was $1425\~1500^{\circ}C$. The hexagonal phase of $Mg_4Ta_2O_9$ and the cubic phase of $SrTiO_3$ were coexisted. The porosity of $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics were reduced with increasing sintering temperature. In the case of $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics sintered at $1475^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 14.51, 82,596 GHz and $-3.14\;ppm/^{\circ}C$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.268-269
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• 2007

In this study, the structural and microwave dielectric properties of the $Sr_5Nb_4O_{15}$ cation-deficient perovskite ceramics with sintering temperature were investigated. All sample of the $Sr_5Nb_4O_{15}$ ceramics were prepared by the conventional mixed oxide method and sintered at $1350^{\circ}C{\sim}1500^{\circ}C$. The bulk density, dielectric constant and quality factor of the $Sr_5Nb_4O_{15}$ ceramics were increased with increasing sintering temperature. In the case of the $Sr_5Nb_4O_{15}$ ceramics sintered at $1500^{\circ}C$ for 5h, the dielectric constant, quality factor and temperature coefficient of the resonant frequency (TCRF) were 22.35, 16,577GHz, +13.40ppm/$^{\circ}C$, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.517-523
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• 2008

The microwave dielectric properties of $LiNb_3O_8-TiO_2$ based ceramics with low firing agents, CuO, $Bi_2O_3$, $B_2O_3$, $SiO_2$, $TiO_2$, were investigated to improve the sintering condition for the LTCC system. According to the X-ray diffraction and SEM, the ceramics of $LiNb_3O_8-TiO_2$ with low firing agents showed no significant second phases within a range of experiments, and fine microstructures. By adding the low firing agents, the sintering temperature decreased from $1200^{\circ}C$ to $925^{\circ}C$. Based on the results of electrical measurements, the $LiNb_3O_8-TiO_2$ ceramics showed a promising microwave dielectric properties for LTCC applications, those are ${\varepsilon}_r$ (dielectric constant) = 44, Q f (quality factor) = 18000, and ${\tau}_f$ (the temperature coefficient of resonant frequency) = $-1.5\;ppm/^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.476-479
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• 2001

The microwave dielectric properties of $[(Pb_{1-x}Ba_{x})_{1/2}La_{1/2}](Mg_{1/2}Nb_{1/2})O_{3}$ ceramics were investigated. When $[(Pb_{0.9}Ba_{0.1})_{1/2}La_{1/2}](Mg_{1/2}Nb_{1/2})O_{3}$ ceramics were sintered at $1250^{\circ}C$ and $1350^{\circ}C$ for 2hr, the microwave dielectric properties were obtained $\varepsilon_{r}=64\sim80$, $Q{\times}f=11,800\sim18,000$. As a result, $[(Pb_{0.9}Ba_{0.1})_{1/2}La_{1/2}](Mg_{1/2}Nb_{1/2})O_{3}$ having $\varepsilon_{r}=80$, $Q{\times}f=11,800$ (at 4 GHz) was developed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.476-479
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• 2001

The microwave dielectric properties of [(Pb$_{1-x}$ Ba$_{x}$)$_{1}$2/La$_{1}$2/](Mg$_{1}$2/Nb$_{1}$2/)O$_3$ ceramics were investigated. When [(Pb$_{0.9}$Ba$_{0.1}$)$_{1}$2/La$_{1}$2/](Mg$_{1}$2/Nb$_{1}$2/)O$_3$ ceramics were sintered at 125$0^{\circ}C$ and 135$0^{\circ}C$ for 2hr, the microwave dielectric properties were obtained $\varepsilon$$_{r}$=64~80, Qxf=11,800~18,000. As a result, [(Pb$_{0.9}$Ba$_{0.1}$)$_{1}$2/La$_{1}$2/](Mg$_{1}$2/Nb$_{1}$2/)O$_3$ having $\varepsilon$$_{r}$=80, Qxf=11,800 (at 4 GHz) was developed.ed.eveloped.ed.

• Electrical & Electronic Materials
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• v.8 no.5
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• pp.594-600
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• 1995

Dielectric properties at microwave frequencies of ($Zr_{0.65}$, $Sn_{0.35}$) $Ti_{1.04}$ $O_{4.04}$ ceramics with additives, NiO as an agent to improve dielectric properties and $B_{2}$ $O_{3}$ as a firing agent were investigated. When 0.5 - 1.5 wt% of NiO is add, the grain growth is inhibited and the shape of the grain is uniformed, Dielectric constant(Fr) and bulk density are increased with raising amount of NiO at sintering temperature of 1330 - 1360.deg. C, but the temperature coefficient of resonant frquency(.epsilon.$_{r}$) decreased gradually as the NiO content increased. The value of Qx $f_{o}$ was increased as the amount of NiO was increased in the range of 0.5 to 1.0 wt% and the Qx $f_{o}$, was decreased slightly with raising sintering temperature. With NiO of 1.0 wt% and at sintering temperature of 1360.deg. C, this ceramics was found to have excellent microwave properties of .epsilon.$_{r}$=37.8, Qx $f_{o}$ = 48.600 and .tau.$_{f}$ = 7 ppm/.deg. C.C.. C.. C.C.. C.. C.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.9
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• pp.459-463
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• 2004

In this study, the (l-x)$TiTe_3O_{8}$-x$MgTiO_3$ ceramics were investigated to obtain the improved dielectric properties of a high temperature stability and a sintering temperature of less than $900^{\circ}C$ which was necessary for the LTCC. According to the X-ray diffraction patterns of the (l-x)$TiTe_3O_{8}$-x$MgTiO_3$(x=0∼1) ceramics, the columbite structure of $TiTe_3O_{8}$ and ilmenite structure of $MgTiO_3$ were coexisted. Increasing the $MgTiO_3$ mole ratio(x), the density and dielectric constant were decreased and temperature coefficient of resonant frequency was moved to the negative direction and the quality factor was increased. In the case of the 0.6$TiTe_3O_{8}$-0.4$MgTiO_3$ ceramics sintered at $830^{\circ}C$ for 3hr., the microwave dielectric properties were $\varepsilon_{\gamma}$=29.3, Q${\times}$$f_{\gamma}$=39.600GHz and $\tau$$_{f}$=+9.3ppm/$^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.20-21
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• 2006

In this study, structural and microwave dielectric properties of the ${Ba_5}{B_4}{O_{15}}$ (B=Ta, Nb} cation-deficient perovskite ceramics with sintering temperature were investigated. All sample of the ${Ba_5}{B_4}{O_{15}}$ (B=Ta, Nb) ceramics prepared by conventional mixed oxide method and sintered at $1325^{\circ}C{\sim}1575^{\circ}C$. The bulk density and dielectric constant of the ${Ba_5}{Ta_4}{O_{15}}$ ceramics were increased continuously with increasing of sintering temperature. And the bulk density and dielectric constant of the ${Ba_5}{Nb_4}{O_{15}}$ ceramics was increased in $1375^{\circ}C{\sim}1400^{\circ}C$ but decerased in $1425^{\circ}C$. In the case of ${Ba_5}{Ta_4}{O_{15}}$ ceramics sintered at $1475^{\circ}C$ and ${Ba_5}{Nb_4}{O_{15}}$ ceramics sintered at $1400^{\circ}C$, The dielectric constant and quality factor, and temperature coefficient of the resonant frequency (TCRF) were 25.15, 53,105 GHz, $-3.06\;ppm/^{\circ}C$ and, 39.55, 28,052 GHz, $5.7\;ppm/^{\circ}C$ respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.12
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• pp.1017-1024
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• 2000

Effect of the microwave dielectric properties and the microstructure on a mole fraction(x=0.1~0.9) of (1-x)Mg$_2$SiO$_4$-xZnAl$_2$O$_4$ ceramics was investigated. When (1-x)Mg$_2$SiO$_4$-xZnAl$_2$O$_4$(x=0.1~0.9) ceramics were sintered at 130$0^{\circ}C$, 135$0^{\circ}C$ and 140$0^{\circ}C$ for 2hr, the microwave dielectric properties were obtained $\varepsilon$r=6.8~8.3, Q.f$_{0}$=36000~77600. On the other hand, the temperature coefficients of resonant frequency($\tau$$_{f}$) were obtained in the properties of -62ppm/$^{\circ}C$ to -49ppm/$^{\circ}C$. In order to adjust the temperature coefficient of resonant frequency($\tau$$_{f}$), CaTiO$_3$was added in (1-x)Mg$_2$SiO$_4$-xZnAl$_2$O$_4$ceramics. 0.7Mg$_2$SiO$_4$-0.2ZnAl$_2$O$_4$-0.1CaTiO$_3$ceramics sintered at 135$0^{\circ}C$ for 2hr showed the excellent microwave dielectric properties of $\varepsilon$r=7.7, Q.f$_{0}$=32000, and $\tau$$_{f}$=-7.9 ppm/$^{\circ}C$.EX>.>.EX>.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.81-85
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• 1996

Microwave dielectric properties of 0.15(B $a_{x}$S $r_{0.05}$)O-0.15(S $m_{2}$(1-y)N $d_{2y}$) $O_{3}$-0.7Ti $o_{2}$(x=o.9~0.1[mol.], y=6[m/o]) ceramics were investigated with BaO compositional ratio. Sintered density and resistivity of specimens were independent on the BaO compositional ratio. In the specimen with x=0.975[mol.], dielectric constant, quality factor and temperature coefficient of resonant frequency had good values of 76.52, 3001(at 3[GHz]) and +0.71[ppm/.ceg. C], respectively. By comparing with the stoichiometric compositions of 78.14, 2938(at 3[GHz])+14.19[ppm/.ceg. C], dielectric constant and quality factor showed similar properties, but the temperature coefficient of resonant frequency was highly improved. (author). refs., figs., tabs.s.s.