• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.430-433
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• 2001

The $0.96MgTiO_{3}-0.04SrTiO_{3}+xCe(x=0{\sim}1.6wt%)$ ceramics were fabricated by the conventional mixed oxide method. The sintering temperature and time were $1300^{\circ}C$, 2hr., respectively. From the X-ray diffraction patterns, it was found that the perovskite $SrTiO_{3}$ and ilmenite $MgTiO_{3}$ structures were coexisted in the $0.96MgTiO_{3}-0.04SrTiO_{3}+xCe(x=0{\sim}1.6wt%)$ ceramics. The dielectric constant$(\varepsilon_{r})$ was increased with addition of Ce. The temperature coefficient of resonant frequency$(\Gamma_{f})$ was gradually varied from positive value to the negative value with increasing the Ce. The temperature coefficient of resonant frequency of the $0.96MgTiO_{3}-0.04SrTiO_{3}+0.2Ce$ ceramics was near zero, where the dielectric constant, quality factor, and $\Gamma_{f}$ were 20.68, 50,272 and ${-0.5ppm/^{\circ}C}$, respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.8
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• pp.376-381
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• 2001

The(1-x) MgTiO$_3$-xSrTiO$_3$(x=0.03~0.04) ceramics were fabricated by the conventional mixed oxide method. The structural and microwave dielectric properties were investigated by XRD, SEM, EDS and network analyzer. The sintering temperature and time were 1275$^{\circ}C$~135$0^{\circ}C$ and 2hours, respectively. In the XRD results of 0.96MgTiO$_3$-0.04SrTiO$_3$ceramics, the perovskite structure of SrTiO$_3$and ilmenite structure of MgTiO$_3$phase were coexisted. The dielectric constant($\varepsilon$(sub)${\gamma}$) and temperature coefficient of resonant frequency($\tau$(sub)f) were increased with addition of SrTiO$_3$. In thie case of 0.96MgTiO$_3$-0.04SrTiO$_3$ ceramics sintered at 13$25^{\circ}C$, the dielectric constant, quality factor(Q) and temperature coefficient of resonant frequency($\tau$(sub)f) were 20.13, 7956(at 7.27GHz), and +1.76ppm/$^{\circ}C$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.1-4
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• 1994

In this study. the microwave dielectric properties, such at dielectric constant(${\varepsilon}_{\gamma}$), unloaded quality factor multiplied with resonant frequency($Q_{u}$.f), and temperature coefficient of resonant frequency(${\tau}_{f}$), were investigated for the low-temperature sintered (Pb, Ca)$ZrO_3$ with $V_2O_{5}$ additives as well as structural properties. As a result, (Pb,Ca)ZrO$_3$ with 0.2 wt% $V_2O_{5}$ additive, sintered at $1200^{\circ}C$, showed good properties like ${\varepsilon}_{\gamma}$ 109, $Q_{u}$.f 2736 GHz, and ${\tau}_{f}$ -2.94 ppm/$^{\circ}C$. Especially ${\tau}_{f}$ was much better than ($Pb_{0.63}Ca_{0.37}$)$ZrO_3$ of which ${\tau}_{f}$ was known to be + 13.4 ppm/$^{\circ}C$, so it seems to be applicated in micorowave device components.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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• pp.840-845
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• 2004

The microstructure and microwave dielectric properties of $(1-x){Mg}_4{Ta}_2{O}_9-xTi{O}_2(x=0\sim0.9)$ ceramics were investigated. The specimens were prepared by the conventional mixed oxide method with sintering temperature of 140$0^{\circ}C$∼150$0^{\circ}C$. To improve the quality factor and the temperature coefficient of resonant frequency,$ Ti{O}_2(\varepsilon\Gamma=100, Q\times f_\Gamma=40,000 GHz,\ta_f= +450 ppm\diagup^{\circ}C $ was added in ${Mg}_4{Ta}_2{O}_9$ceramics. The dielectric and structural properties were investigated. According to the XRD patterns, $(1-x){Mg}_4{Ta}_2{O}_9-xTi{O}_2(x=0\sim0.9)$ ceramics had the ${Mg}_4{Ta}_2{O}_9$ phase(hexagonal) and ${MgTi}_2{O}_5$phase(orthorhombic). The dielectric constant($\varepsilon_r$). quality($Qtimes{f}_r$${\tau}_f$) of the $(1-x){Mg}_4{Ta}_2{O}_9-xTi{O}_2(x=0\sim0.9)$ ceramics were 8.12∼18.59, 18,750∼186,410 GHz and －36.02∼＋3.46 ppm/$^{\circ}C$, respectively.

• 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$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.2
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• pp.67-72
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• 2004

The microwave dielectric properties and microstructure of the (1-x)$Mg_4Ta_2O_{9-x}TiO_2$(X=0, 0.3, 0.4) ceramic were, investigated. The specimens were prepared by the conventional mixed oxide method with sintering temperature of $1350^{\circ}C$∼$1425^{\circ}C$. According to the XRD patterns, the (1-x)$Mg_4Ta_2O_{9-x}TiO_2$(X=0, 0.3, 0.4) ceramics have the $Mg_4Ta_2O_{9}$ phase(hexagonal). The dielectric constant($\varepsilon$$_{\gamma}$) and density increased with sintering temperature and mole fraction of x. To improve the quality factor and the temperature coefficient of resonant frequency, TiO$_2$($\varepsilon_{r}$=100, $Q{\times}f_{r}$=40,000GHz, $\tau$$_{f}$=＋450 ppm/$^{\circ}C$) was added in $Mg_4Ta_2O_{9}$ ceramics. In the case of the $0.7Mg_4Ta_2O_{9}$-$0.3TiO_2$ and the $0.6Mg_4Ta_2O_{9}$-$0.4TiO_2$ceramics sintered at $1400^{\circ}C$ for 5hr., the microwave dielectric properties were $\varepsilon$$_{\gamma}$=11.72, $Q{\times}f_{r}$=126,419GHz, $\tau_{f}$=-31.82 ppm/$^{\circ}C$ and $\varepsilon_{r}$=12.19, $Q{\times}f_{r}$=109,411GHZ, $\tau$$_{f}$= -17.21 ppm/$^{\circ}C$, respectively.