• Journal of the Korean Ceramic Society
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• v.28 no.5
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• pp.359-364
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• 1991

The effects of Pb5Ge3O11 on the sinterbility and lattice variation of the semiconducting 0.15 mol% Y2O3 doped BaTiO3 have been investigated as functions of additive contents (from 0.25 mol% to 2.5 mol%) and sintering temperatures (from 110$0^{\circ}C$ to 130$0^{\circ}C$). As the amount of Pb5Ge3O11 increases, the sinterbility of BaTiO3 increases abruptly at around 115$0^{\circ}C$. During the sintering, the most of Pb+2 ions in additives penetrate into BaTiO3 lattices and Ge+4 ions present at grain boundaries. Therefore the c lattice of the BaTiO3 increases largely and then the tetragonality increases due to the diffusion of the Pb+2 ions.

• Analytical Science and Technology
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• v.15 no.1
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• pp.15-19
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• 2002

The pretreatment of tungsten added $BaTiO_x$ ceramics was performed to improve the recovery of Ba, Ti and W. $BaTiO_x$ ceramics were digested with HF : HCl ( 1 : 2 ) mixture in an acid digestion bomb at $220^{\circ}C$ for 3 hrs. The concentration of Ba, Ti and W were determined by ICP-AES. Recoveries of Ba, Ti and W were 99.6%, 99.8% and 99.2%, respectively. And their C.V. values were 1.02%, 0.73% and 1.79%. Using this method, the analytical results of Ba, Ti and W for a real sample were obainted to be 25.9% (w/w), 38.8% (w/w) and 3.31% (w/w), respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.6
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• pp.278-282
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• 2010

The doping effect of thulium on electrical properties and degradation behavior in barium titanate ceramics ($BaTiO_3$) was investigated in terms of generations of core-shell structure and micro-chemical changes through highly accelerated degradation test. The dielectric specimens of pellet type and multi-layered sheets were prepared by using $BaTiO_3$ with undoped and doped with 1 mol% $Tm_2O_3$. The $BaTiO_3$ ceramics doped with 1 mol% $Tm_2O_3$ had 40% higher dielectric constant (${\varepsilon}$ = 2700) than that of the undoped $BaTiO_3$ specimen at curie temperature and met X7R specification. According to the result of highly accelerated degradation test conducted at $150^{\circ}C$, 70 V, and 24 hr, the oxygen diffusion was declined in dielectrics doped with 1 mol% $Tm_2O_3$. The $Tm^{3+}$ ion substituted selectively Ba site and Ti site and contributed to the generation of the core-shell structure. Oxygen vacancies occurred by substitution for Ti site could reduce excess oxygen that reacted to the Ni electrode.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1491-1493
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• 2002

The 0.5$Ba_2Ti_9O_{20}$-0.5Mg$TiO_3$ ceramics were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature by XRD. According to the X-ray diffraction patterns, major phases of the 0.5$Ba_2Ti_9O_{20}$-0.5Mg$TiO_3$ ceramics were coexisted. Also the secondary phase of Mg$Ti_2O_5$, Ba$Mg_6Ti_6O_{19}$ and the unreacted $TiO_2$ phase were existed. In the case of 0.5$Ba_2Ti_9O_{20}$-0.5Mg$TiO_3$ ceramics sintered $1350^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 33.7, 54,900GHz, -12.5ppm/$^{\circ}C$, respectively.

• Korean Journal of Materials Research
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• v.17 no.10
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• pp.548-554
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• 2007

[ $BaTiO_3$ ] thick film by an interfacial polymerization method was prepared at the liquid/liquid interface between benzyl alcohol saturated solution with the basic catalyst [diethyl amine ($NHEt_2$) or triethylamine ($NEt_3$)], and the water dissolved with $TiO_2$ and $Ba(CH_3COO)_2$. The film thickness increased gradually with an increase in diethyl amine($NHEt_2$) or triethylamine($NEt_3$) volume and the reaction time. The homogeneity of $BaTiO_3$ thick film after sintered at $600^{\circ}C$ was confirmed by EPMA analysis, which showed that both of Ba and Ti element were homogeneously distributed on the surface as well as in the perpendicular direction of the film. The thickness of $BaTiO_3$ film obtained by this process was $8.75\;{\mu}m$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.8-11
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• 1988

(1-x-y)Pb($Zn_{1/3}Nb_{2/3})0_3-BaTiO_3PbTiO_3(0.05{\leq}x{\leq}0.20, 0.05{\leq}y{\leq}0.15$) ternary compound ceramics were fabricated by the mixed oxide method. The dielectric properties with temperature and frequency of the specimens were investigated. Relative dielectric constants of the specimens were increased with $BaTiO_3$ contents. Increasing the $BaTiO_3$contents, the variation in the relative dielectric constant with frequency, the temperature coefficient of capacitance (TCC) and the dielectric loss were decreased.

• Journal of the Korean Ceramic Society
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• v.40 no.12
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• pp.1177-1182
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• 2003

The porous sensing materials for BaTiO$_3$ gas sensors were fabricated by adding the graphite powders. The crystalline structure and microstructure of the porous BaTiO$_3$-based ceramics were studied. All the sintered bodies showed a tetragonal perovskite structure. The porosity increased with increasing graphite contents. This is mainly due to an enhanced evolution of CO and $CO_2$ gases resulting from the exothermic reactions of graphite and oxygen during the sintering. It was found that the discrepancy in the resistivities measured in air and CO atmospheres at high temperatures (>∼20$0^{\circ}C$) became remarkable with increasing temperature. The sensitivity of CO gas increased with porosity, since the reactions between CO gas and $O_2$$^{[-10]}$ and between CO gas and $O^{[-10]}$ are active due to the formation of many reaction sites. The porous BaTiO$_3$-based ceramics could be promising as a sensing material for CO gas sensors.

• Journal of Powder Materials
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• v.28 no.2
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• pp.127-133
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• 2021

One-dimensional (1D) piezoelectric nanostructures are attractive candidates for energy generation because of their excellent piezoelectric properties attributed to their high aspect ratios and large surface areas. Vertically grown BaTiO₃ nanotube (NT) arrays on conducting substrates are intensively studied because they can be easily synthesized with excellent uniformity and anisotropic orientation. In this study, we demonstrate the synthesis of 1D BaTiO₃ NT arrays on a conductive Ti substrate by electrochemical anodization and sequential hydrothermal reactions. Subsequently, we explore the effect of hydrothermal reaction conditions on the piezoelectric energy conversion efficiency of the BaTiO₃ NT arrays. Vertically aligned TiO₂ NT arrays, which act as the initial template, are converted into BaTiO₃ NT arrays using hydrothermal reaction with various concentrations of the Ba source and reaction times. To validate the electrical output performance of the BaTiO₃ NT arrays, we measure the electricity generated from each NT array packaged with a conductive metal foil and epoxy under mechanical pushings. The generated output voltage signals from the BaTiO₃ NT arrays increase with increasing concentration of the Ba source and reaction time. These results provide a new strategy for fabricating advanced 1D piezoelectric nanostructures by demonstrating the correlation between hydrothermal reaction conditions and piezoelectric output performance.

• Journal of the Korean Ceramic Society
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• v.46 no.2
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• pp.181-188
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• 2009

The electrical property and microstructure in $BaTiO_3$ ceramics doped rare-earth ions with intermediate ionic size ($Dy^{3+},Ho^{3+},Y^{3+}$) were investigated. Microstructures have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Incorporation of rare-earth ions to $BaTiO_3$ ceramics depended on their ionic radius sensitively. Compared to Ho and Y ions, Dy ions provide $BaTiO_3$ ceramics with the high rate of densification and well-developed shell formation, due to their high solubility in the $BaTiO_3$ lattice, but the microstructure of Dy doped $BaTiO_3$ ceramics is unstable at high temperature, because Dy ions could not play a role of grain growth inhibition, leading to diffuse into $BaTiO_3$ lattice continuously after completion of densification during sintering. Comparing electrical property and microstructure, it is shown that the reliability of capacitor improved by high shell ratio.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.6
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• pp.367-371
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• 2014

We investigated dielectric relaxation properties of $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ ceramics by addition (0~0.3 wt%) of $(Ba,Ca)SiO_3$ glass frit. All composition of $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ added $(Ba,Ca)SiO_3$ glass frit showed the same crystallographic properties, coexistence of orthorhombic and tetragonal phase. By increasing addition of $(Ba,Ca)SiO_3$ glass frit, the Curie temperatures of $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ ceramics were decreased, whereas maximum dielectric constants of $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ ceramics were dramatically increased. Especially the deviations of Curie temperature $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ ceramics were increased by increasing amount of $(Ba,Ca)SiO_3$ glass frit, and it indicated that $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ ceramics added $(Ba,Ca)SiO_3$ glass frit have relaxor characteristics.