• Journal of the Korean Ceramic Society
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• v.30 no.2
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• pp.101-106
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• 1993

Effects of CaO on microwave dielectric properties of (Ba, Pb)O-Nd2O3-TiO2 ceramic ystem were investigated. As the content of CaO increases, the sintered bulk density decreases due to the decrease of sinterability. However, with increasing the sintering tmperature, the relative dielectric constants increases. This has been attributed on the formation of the 2nd phase inclusion, TiO2(rutile). The Q values increase due to the compensation effect of Ca ions up to 1 wt%, and then decrease due to the interfacial relaxation effects. The temperature coefficient of resonance frequency increases to a positive direction with increasing the amounts of CaO.

• Journal of the Korean Ceramic Society
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• v.12 no.2
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• pp.10-14
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• 1975

Bodies whose compositions are in the ternary system BaCO3-TiO2-SnO2 containing from 5 to 90 mol % stannic oxide were prepared to improve the thermal characteristics of barium titanate dielectrics. Bodies having dielectric constant (K) of 2100 at 1 KHz, low negative temperature coefficients of 1500ppm up to about 9$0^{\circ}C$, Curie Temperature of 2$0^{\circ}C$, and dissipation factor of 0.2-0.4% were obtained with addition of 15 mole % stannic oxide.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.315-320
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• 1988

The Nb doped BaTiO3 was synthesized by coprecipitation method using H2O2 media in region from pH 8 to pH 11. The powder prepared by using this method was crystallized at about 20$0^{\circ}C$ and average particle size was controlled by heat treatment. Because of preparation having fine particle and relatively narrow particle size distribution, high performance PTC device was made of these precipitated powders.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.284-284
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• 2010

YBCO ceramic specimens were fabricated by added $BaTiO_3$ as donors and sintered $950^{\circ}C$/24hrs. Average grain size decreased with increased in added $BaTiO_3$. Affect to grain growth. XRD result, peak strength was lowed then crystallization not well all specimens. All specimens critical temperature about 90k.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.32-32
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• 2008

Microstructure and positive temperature coefficient of resistivity (PTCR) characteristics of $0.9BaTiO_3-0.1(Bi_{0.5}Na_{0.5})TiO_3$ [BaBiNT] ceramics doped with $Nb_2O_5$ were investigated in order to develop the Pb-free high Curie temperature ($T_c$)(>$160^{\circ}C$) PTC thermistor. The BaBiNT ceramics showed a tetragonal perovskite structure, irrespective of the added amount of $Nb_2O_5$. They also have a homogeneous microstructure. The resistivity of BaBiNT ceramics was gradually decreased by doping $Nb_2O_5$, which might be due to $Nb^{+5}$ ions substituting for $Ti^{+4}$ sites. The PTCR characteristics of BaBiNT ceramics appeared when the amount of doped $Nb_2O_5$ exceeded 0.0025mol%. Moreover, the abrupt grain growth was observed for the 0.03mol% $Nb_2O_5$added BaBiNT ceramics. It showed an especially high $T_c$ of approximately $172^{\circ}C$ and good PTCR characteristics of a high $\rho_{max}/\rho_{min}$ ratio ($2.96\times10^3$), a high resistivity temperature factor (11.40/$^{\circ}C$) along with a relatively low resistivity ($3.5\times10^4\Omega{\cdot}cm$).

• Journal of the Korean Ceramic Society
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• v.43 no.1 s.284
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• pp.62-67
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• 2006

Time-of-flight impact-collision ion scattering spectroscopy (TOF-ICISS) using 2 keV $He^+$ ion was applied to study the geometrical structure of the $BaTiO_3$ thin film which was grown on the MgO(100) surface. Hetero-epitaxial $BaTiO_3$ layers were formed on the MgO(100) surface by thermal evaporation of titanium followed first by oxidation at $400^{\circ}C$, subsequently by barium evaporation, and finally by annealing at $800^{\circ}C$. The atomic structure of $BaTiO_3$ layers was investigated by the scattering intensity variation of $He^+$ ions on TOF-ICISS and by the patterns of reflection high energy electron diffraction. The scattered ion intensity was measured along the <001> and <011> azimuth varying the incident angle. Our investigation revealed that perovskite structured $BaTiO_3$ layers were grown with a larger lattice parameter than that of the bulk phase on the MgO(100) surface.

• The Korean Journal of Ceramics
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• v.5 no.2
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• pp.189-194
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• 1999

Crystallization of glasses in the system (Ca, Sr, Ba)$O-Al_2O_3-B_2O_3-SiO_2-TiO_2$ and dielectric properties of crystallized glasses were investigated. As increasing B2O3 content and decreasing SiO2 content in the glass, the major crystalline phase changed from $(Sr, Ba)_2TiSi_2O_8$ to (Ca, Sr, Ba)TiO3, the dielectric constant of crystallized glasses increased and the Temperature Coefficient of Capacitance (TCC) changed to negative. The dielectric constant and TCC was estimated for (Sr, Ba)2TiSi2O8 phase as 18 and -440 $ppm/^{\circ}C$, respectively and for (Ca, Sr, Ba)TiO3 phase as 307 and -1900 $ppm/^{\circ}C$, respectively. The dielectric properties of (Ca, Sr, Ba)TiO3 phase (in this study) were similar to those of (Ca, Ba) TiO_3 solid-solution^12)$, but $(Sr, Ba)_2TiSi_2O_8$ phase (in this study) and $Sr_2TiSi_2O_\;8^4$ showed the different properties.

• Journal of the Korean Ceramic Society
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• v.29 no.4
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• pp.259-264
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• 1992

The crystal structures and the bonding characteristics in $(Ba_xPb_{1-x})TiO_3$ have been investigated by X-ray diffraction analysis and infrared spectrophotometry. As $Ba^{2+}$ ion in $BaTiO_3$ were substituted by $Pb^{2+}$ ion, the structures were changed to orthorhombic from tetragonal, and also the covalent character in Ti-O bond increased, and then the dielectric constants decreased gradually. In the mixed oxide containing $Pb^{2+}$ ion more than 50%, the change-transfer energy of titanium ion increased.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1516-1519
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• 1996

In this paper, a study on the electrical properties of ternary compound ceramics $[(1-y-x)BaTiO_{3}-ySrTiO_{3}-xMgTiO_3]$ fabricated 7 samples with each mol[%] by using the mixed oxide method. In this case, the sintering temperature were at $1,250[^{\circ}C]$ for 2[hr]. Also made ceramic capacitors from 7 samples, temperature coefficient of the capacitance and the variation of relative dielectric constants and loss with fixed frequency (1KHZ) were studied. In some ceramic capacitors, has shown very good properties of the dielectric constants and loss. In case of BSM-11 ceramic capacitor, is sure to the commercial capacitor which shows steady properties.

• Journal of the Korean Ceramic Society
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• v.36 no.7
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• pp.705-710
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• 1999

Stability and chemical durability for aqueous casting of BaTiO3 slurry with polycarylic acid(PAA) were studied. PAA was well chemisorbed on surface of BaTiO3 powder at neutral pH but did not chemically adsorbed at low pH. The amount of Ba dissolution in aqueous BaTiO3 slurry was abruptly increased at strong acid pH2 and also at high amount of PAA. Protection of Ba dissolution and stability of slurry could be obtained through the optimization of slurry conditions such as pH amount of surfactant and solid content.