• Electrical & Electronic Materials
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• v.10 no.7
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• pp.674-681
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• 1997

Ternary compound ceramics, (1-y-x) BaTiO$_3$-y SrTiO$_3$-x MgTiO$_3$(0.00 x 0.20), were fabricated by the conventional ceramic process. The structural and dielectric properties of specimens were investigated while varying the composition and sintering temperature(1,200~1,45$0^{\circ}C$) in order to obtain the optimum condition of capacitor. As is well known, Curie temperature(T$_{c}$) of high dielectric-based ceramic(BaTiO$_3$) was shifted and temperature of capacitance was decreased in according to increase of solid solution with (Sr, Mg)TiO$_3$. As a result, a suitable condition of compound rate for capacitor was obtained such as the BSM-11(0.8BaTiO$_3$-0.1SrTiO$_3$-0.1MgTiO$_3$), and sintering temperature was sintered at 1,25$0^{\circ}C$ for two hours. In this case, dielectric constant<1,300, dielectric loss(tan$\delta$)<0.03, and the variation rate of capacitance had less than 3% in the range -10~7$0^{\circ}C$.>.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.547-550
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• 2000

The (1-x)MgTiO$_3$-xSrTiO$_3$(x=0.03~0.04) ceramics were fabricated by the conventional mixed oxide method. The sintering temperature and time were 125$0^{\circ}C$~135$0^{\circ}C$, 2hr., respectively. From the X-ray diffraction patterns, it was found that the perovskite SrTiO$_3$ and ilmenite MgTiO$_3$ structures coexisted in the (1-x)MgTiO$_3$-xSrTiO$_3$(x=0.03~0.04) ceramics. The dielectric constant($\varepsilon$$_{r}$) was increased with addition of SrTiO$_3$. The temperature coefficient of resonant frequency($\tau$$_{f}$) was gradually varied from negative value to the positive value with increasing the SrTiO$_3$. The negative temperature coefficient of resonant frequency of the magnesium titanate was adjusted to near zero at x=0.036, where the dielectric constant, quality factor, and $\tau$$_{f}$ were 20.65, 95120, and +1.3ppm/$^{\circ}C$, respectively. The temperature stability of qualify factor in (1-x)MgTiO$_3$-xSrTiO$_3$(x=0.03~0.04) ceramics increased as the amount of MgTiO$_3$./TEX>.

• Korean Journal of Materials Research
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• v.14 no.2
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• pp.115-120
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• 2004

Perovskite barium-strontium titanate, $(Ba, Sr)TiO_3$ was prepared and effects of $Sb_2$O$_3$ additives on its PTCR properties were investigated. $The (Ba,Sr)TiO_3$ with 0.05～0.25 mol% $Sb_2$$O_3$ showed semiconducting PTCR behavior and anomalous grain growth was also observed when it was sintered above $1330^{\circ}C$. It was considered that charge compensation by doping 8b203 as well as abnormal grain growth by sintering lead to resistivity reduction from insulating to semiconducting transition.

• Journal of Sensor Science and Technology
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• v.18 no.6
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• pp.456-461
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• 2009

Perovskite-structure $Sr(Ti_{1-x}Fe_x)O_3$ thick films, in which x is 0.4 or 0.6, were prepared by normal ceramic process on alumina substrate. Electrical resistance was measured as a function of thermal treatment condition including atmosphere, time, and temperature. The resistance of $Sr(Ti_{1-x}Fe_x)O_3$ films is lower than those of $SrTiO_3$ or $SrFeO_3$ films. The temperature coefficient of resistance over $550^{\circ}C$ was measured to be 0 for the $Sr(Ti_{1-x}Fe_x)O_3$ films after thermal treatment at $1100^{\circ}C$ in air. The sensing property of the films was also measured as a function of temperature and gas such as $O_2$, CO, $CO_2$, NO and $NO_2$. $Sr(Ti_{1-x}Fe_x)O_3$ films showed a good sensing property for $O_2$, but no sensing signal for CO, $CO_2$, NO and $NO_2$.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1075-1079
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• 1999

LaSrCoO3 thin films were spin-coated onto the SrTiO3(100) substrates by the chemical solution process. X-ray diffraction $\theta$-2$\theta$ scans and X-ray diffraction $\beta$ scans were used to determine the crystallinity and in -plane alignment behavior of the films. The X-ray diffraction pattern showed the film obtained by annealing at 80$0^{\circ}C$ was highly oriented. The X-ray diffraction pole-figure analysis and reciprocal-space mapping (2$\theta$-$\Delta$$\omega$ scans) of the resulting film showed that the film comprising the pseduocubic phase had an epitaxial relationship with the SriO3 substrate.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.56-62
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• 1999

In this study, (Ba, Sr)$TiO_3$ thin films were etched with $Cl_2$/Ar gas mixing ratio in an inductively coupled plasma (ICP) by varying the etching parameter such as rf power, dc bias voltage, and chamber pressure. The etch rate was 56 nm/min under $Cl_2$/($Cl_2$+Ar) gas mixing ratio of 0.2, rf power of 600 W, dc bias voltage of 250 V, and chamber pressure of 5 mTorr. At this time, the selectivity of BST to Pt, $SiO_2$ was respectively 0.52, 0.43. The surface reaction of the etched (Ba, Sr)$TiO_3$ thin films was investigated with X-ray photoelectron spectroscopy (XPS). Ba is removed by chemical reaction between Sr and Cl to remove Sr. Ti is removed by chemical reaction such as $TiCl_4$ with ease. The results of secondary ion mass spectrometer (SIMS) analysis compared with the results of XPS analysis and the results were the same.

• Journal of the Korean Chemical Society
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• v.25 no.4
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• pp.236-245
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• 1981

The electrical conductivities of oxidized pure and Ni-doped $SrTiO_3$ single crystals were measured as a function of the oxygen partial pressure($Po_2$) at temperature from 700 to $1200^{\circ}C$ and $Po_2$ of $10^{-8}$ to $10^{-1}$ atm. Plots of log ${\sigma}$ vs. 1/T at constant $Po_2$ were found to be linear, and the activation energies obtained from the slopes of these plots have an average value of 1.34 eV for oxidized pure and 1.06 eV for oxidized Ni-doped $SrTiO_3$ single crystals at $Po_2$'s between $10^{-8}$ to $10^{-1}$ atm. The log ${\sigma}$ vs. log $Po_2$ curves at constant temperature were found to be linear with an average slope of ${\frac{-1}{5.6}}\;{\sim}\;{\frac{-1}{6.2}}$ in the $Po_2$ ranges. From the agreement between experimental and theoretically predicted values for the electrical conductivity dependences on $Po_2$, an oxygen vacancy defect model was found applicable to oxidized pure and Ni-doped $SrTiO_3$ single crystals over the temperature range, 700~$1200^{\circ}C$. Conduction mechanisms were proposed to explain the dependences of electrical conductivity on temperature and $Po_2$.

• Journal of the Korean Ceramic Society
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• v.33 no.2
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• pp.177-182
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• 1996

strontium titanate (SrTiO3) thin films deposited on Pt/MgO were prepared by Plasma Enhanced Metal Orgainc Chemical vapor Deposition (Pe-MOCVD). The crystallinity of SrTiO3 thin films increased with increasing depo-sition temperature and SrF2 second phase disappeared at 55$0^{\circ}C$ The films showed a dielectric constant of 177 and a dissipation factor of 0.0195 at 100 kHz. The variation of capacitance of the films with applied voltage was small showing paraelectric properties. The charge storage density and leakage current density were 40fC/${\mu}{\textrm}{m}$2 and 3.49$\times$10-7 A/cm2 at 0.25 MV/cm, respectively.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.123-130
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• 1997

In this study, (Sr.Pb.Ca)TiO3-Bi2O3.3TiO2(SPCT) systems were investigated to develop a new material which has a high dielectric constant, a low dielectric loss and a small TCC(Temperature Coefficient of Capa-citance), and are suitable for high voltage applications as a function of the additions of Bi2O3.3TiO2 from 5 mol.% to 9 mol.%. The result obtained from our investigation showed that up to 6 mol.% Bi2O3.3TiO ad-dition the dielectric constant increased and it deteriorated at higher concentrations with increasing amount of the acicular grains. As a result of some dopants (SiO2, Nb2O3, MnO2) addition to SPCT, the specimens with MnO2 showed good dielectric properties. The dielectric constant decreased, but the TCC was improved with the addition of MnO2 from 0.15 wt.% to 0.45 wt. %.

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.401-405
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• 2004

Undoped SrB $i_2$T $a_2$O$_{9}$, donor-doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ and acceptor-doped SrB $i_2$(Ta$_{0.99}$Ti$_{0.01}$)$_2$O$_{8.99$ ceramics were prepared and their microstructure, ferroelectric P-E hysteresis and Curie temperature were investigated. Grain size did not influence P-E hysteresis curve in undoped SrB $i_2$T $a_2$O$_{9}$ ceramics. Donor-Doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ ceramics showed more saturated P-E hysteresis curve with larger remanent polarization (P$_{r}$) than undoped SrB $i_2$T $a_2$O$_{9}$ ceramics while acceptor-doped SrB $i_2$(Ta$_{0.99}$Ti$_{0.01}$)$_2$O$_{8.99}$ ceramics led to a pinched P-E hysteresis loop. Larger polarization in donor-doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ ceramics resulted from easier domain wall motion by Sr-vacancies.