• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.12
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• pp.1011-1016
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• 2000

The (1-x)MgTi $O_3$-xSrTi $O_3$(x=0.02~0.08) ceramics were fabricated by the conventional mixed oxide method. The sintering temperature and time were 125$0^{\circ}C$~1375$^{\circ}C$ and 2hours. The structure and microwave dielectric properties were investigated with sintering temperature and composition ratio. From the X-ray diffraction patterns, the cubic SrTi $O_3$and hexagonal MgTi $O_3$structures were coexisted in the (1-x)MgTi $O_3$-xSrTi $O_3$(x=0.02~0.08) ceramics. The dielectric constant($\varepsilon$$_{r}$) was increased and the temperature coefficient of resonant frequency($\tau$$_{f}$)was decreased with addition of SrTi $O_3$. The temperature coefficient of resonant frequency($\tau$$_{f}$) was gradually varied from negative value to positive value with increasing SrTi $O_3$. In the case of 0.96MgTi $O_3$-0.04SrTi $O_3$ceramics sintered at 130$0^{\circ}C$, the dielectric constant, quality factor and temperature coefficient of resonant frequency were 20.5, 5918(at 7.33GHz) and +10ppm/$^{\circ}C$, respectively.y.y.y.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.194-199
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• 2011

In this study, non-stoichiometric 1-x$[(K_{0.5}Na_{0.5})_{0.97}(Nb_{0.96}Sb_{0.04})O_3]$ + x $CeMnO_3$ + 0.8 mol%CuO + 0.2 wt% $Ag_2O$ (x=0, 0.005) ceramics were prepared by a conventional mixed oxide and carbonate method, their dielectric and piezoelectric properties were investigated with the variations of sintering temperature. As $CeMnO_3$ substitution incereased, the density, piezoelectric constant($d_{33}$) and dielectric constant($\varepsilon_r$) were increased and the mechanical quality factor(Qm) was decreased. At the sintering temperature of $1100^{\circ}C$, the density, electromechanical coupling factor($k_p$), dielectric constant($\varepsilon_r$) and piezoelectric constant($d_{33}$) of 0.5mol% $CeMnO_3$ specimen showed the optimun values of 4.475 $g/cm^2$, 0.437, 552 and 166 pC/N, respectively. However, the mechanical quality factor($Q_m$) showed the minimum value of 380.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.66-67
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• 2005

In this study, in order to develop multilayer piezoelectric actuator, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3-Na_2CO_3$ as sintering aids and their piezoelectric and dielectric characteristics were investigated with the function of PNN substitution. With increasing PNN substitution, dielectric constant(${\varepsilon}r$), electromechanical coupling factor(kp), and piezoelectric d constant($d_{33}$) were increased at 10~12[mol%] PNN substitution and then decreased at all sintering temperature. With increasing PNN substitution, phase changed from tetragonal to rhombohedral at [10~12mol%] PNN substitution. At the 12[mol%] PNN substituted PMN-PZT composition ceramic sintered at 950[$^{\circ}C$], density, ${\varepsilon}r$, kp, $d_{33}$ and Qm showed the optimum value of 7.79[$g/cm^3$], 1160, 0.599, 419[pC/N) and 894, respectively for multilayer piezoelectric actuator application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.477-483
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• 2003

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.855-861
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• 2006

Sinterability and microwave dielectric properties of $xZWO_{4}-(1-x)TiO_{2}$ ceramic systems with zinc-borosilicate glass and $TiO_{2}$ contents for LTCC(Low Temperature Co-fired Ceramics) were investigated. The addition of $3{\sim}10\;wt%$ ZBS glass ensured the sinterability below $900^{\circ}C$. In general, increasing ZBS glass content seemed to enhance the sinterability, but the quality factor($Qxf_{0}$) significantly decreased due to the formation of an excessive liquid and second phases. As for the addition of $TiO_{2}$, the dielectric constant(${\varepsilon}_{r}$) and temperature coefficient of resonant frequency(${\tau}_{f}$) showed to increase, while the quality factor($Qxf_{0}$) did not show an apparent change. The composition of $0.7xZnWO_{4}-0.3TiO_{2}$ ceramics sintered at $900^{\circ}C$ with 5 wt% ZBS glass demonstrated 21.6 in dielectric constant(${\varepsilon}_{r}$), 14,800 in quality factor($Qxf_{0}$), and $+5\;ppm/^{\circ}C$ in temperature coefficient of resonant frequency(${\tau}_{f}$).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.203-204
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• 2008

In this study, in order to develop the multilayer piezoelectric actuator and ultrasonic resonator, PMN-PNN-PZT ceramics were fabricated by the variations of ball size at sintering temperature of $900^{\circ}C$ and their piezoelectric and dielectric characteristics were investigated as a function of the variations of ball size. When the ball size was 3mm$\phi$, density, dielectric constant$({\varepsilon}r)$, electromechanical coupling factor(kp) and piezoelectric d constant$(d_{33})$ were increased. At the ball size of 3mm$\phi$, the specimen showed the optimum values of density=7.909g/$cm^3$, kp=0.592, Qm=1292, $d_{33}$=368pC/N, $\varepsioln_r$=1502, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.284-287
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• 2002

The $BaTi_{4}O_{9}$ ceramics with CoO(0.5wt%) were prepared by the conventional mixed oxide method. The sintering temperature and time were $1350^{\circ}C$, 3hr., respectively. The structural properties were investigated with sintering temperature by XRD. Also the microwave dielectric properties of the $BaTi_{4}O_{9}$ ceramics were studied. According to the X -ray diffraction patte구 of the $BaTi_{4}O_{9}$ ceramics with CoO(0.5wt%), the orthorhombic $BaTi_{4}O_{9}$ structure was appeared. In the case of $BaTi_{4}O_{9}$ ceramics with CoO(0.5wt%), dielectric constant $(\varepsilon_{r})$, quality factor$(Q{\times}f_r)$ and temperature coefficient of resonant frequency$(\tau_{f})$ were 40.8, 43,270 and $2.5ppm/^{\circ}C$, respectively.ࠀࠀ Ѐ耀
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• Journal of the Korean Ceramic Society
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• v.31 no.11
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• pp.1293-1298
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• 1994

(Zr, Sn)TiO4 powders were prepared in 0.05~0.13 ${\mu}{\textrm}{m}$ by coprecipitating (Zr4+, Ti4+)hydroxide on SnO2 particles and followed by calcination at 90$0^{\circ}C$ for 2 h. They sinter to 95% of relative density at 140$0^{\circ}C$ for 2 h. and shows dielectric constant, $\varepsilon$r=37.5 and quality factor, Qxf(GHz)=46,000. With 3 mol% of ZnO it sinters to rel=97.5%, $\varepsilon$r=39 and Qxf(GHz)=40,050 at 135$0^{\circ}C$ for 2 h., but raising sintering temperature to 140$0^{\circ}C$ deteriorates quality factor, relative density and microstructure with developing second phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.279-279
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• 2007

Synthesis and dielectric properties of glass-ceramic composites with zinc borosilicate glass(here after ZBS glass) were investigated as functions of $ZnAl_2O_4$ phase synthesis method, glass addition (50~60 vol%) and sintering temperature ($600{\sim}950^{\circ}C$ for 2 hrs). The 50 vol% ZBS glass-$Al_2O_3$ and 60 vol% ZBS glass-$ZnAl_2O_4$ ensured successful sintering below $900^{\circ}C$. But the composition of 100-x-y vol% ZBS glass-x vol% $Al_2O_3-y$ vol% ZnO exhibited poor sinterability below $900^{\circ}C$ and the swelling phenomenon occurred in this composite with the large amount of ZBS glass. The sintering behavior of Glass-ceramic composites was affected by the crystallization of $ZnAl_2O_4$ which was formed by the reaction between ZBS glass and $Al_2O_3$. Dielectric constant (${\varepsilon}_r$), $Q{\times}f$ value and temperature coefficient of resonant frequency (${\tau}_f$) of the composite with 50 and 60 vol% ZBS glass contents demonstrated $ZBS-Al_2O_3({\varepsilon}_r=5.7)$, $ZBS-ZnAl_2O_4({\varepsilon}_r=5.8)$ which is applicable to substrate requiring an low dielectric properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.559-562
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• 2000

In this paper, coplanar waveguide fed antennas (CPWFAs) insetting two slits to boundary of the square microstrip patch are presented. These slits play roles in not only lowering a resonant frequency but also fine-tuning for the proposed antenna together with open stub of CPW feed line. The CPWFAs were designed and manufactured using microwave dielectrics (Al,Mg)TaO$_2$ having high dielectric-constant ($\varepsilon$r=20). The return loss and input impedance of the CPWFAs were investigated in terms of the slit length and open stub length of CPW feed line. It is shown that a resonant frequency decreases as the slit length increases.