• 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 Magnetics
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• v.13 no.2
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• pp.57-60
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• 2008

This study examined the effect of various types of epitaxial strain on the magnetic properties of $SrRuO_3$ thin films. Epitaxial $SrTiO_3$ (001), $SrTiO_3$ (110), and $SrTiO_3$ (111) substrates were used to apply different crystal symmetries to the grown films. The films were grown using pulsed laser deposition. The X-ray diffraction patterns of the films grown under optimum conditions showed very clear peaks for the $SrRuO_3$ film and $SrTiO_3$ substrates. The saturated magnetic moment at 5 K after 7 Tesla field cooling was $1.2-1.4\;{\mu}_B$/Ru. The magnetic easy axis for all three types of films was along the surface normal. The magnetic transition temperature for the $SrRuO_3$ film with lower symmetry was slightly larger than the $SrRuO_3$ film with higher symmetry.

• Journal of the Korean Ceramic Society
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• v.39 no.11
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• pp.1023-1027
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• 2002

In this paper, we have prepared phase-pure $SrTiO_3:\;Pr^{3+}$ phosphor powder by Supercritical Fluid Mixing using $Sr(OH)_2{\cdot}8H_2O$ and $TiO_2$ powders as starting materials. Its luminescent properties were investigated in comparison with $SrTiO_3:\;Pr^{3+}$ powders prepared by solid-state method with conventional mixing. $SrTiO_3:\;Pr^{3+}$ phosphor powders by Supercritical Fluid Mixing have spherical shapes and narrow particle size distribution. We have investigated the luminescent properties of $SrTiO_3:\;Pr^{3+}$ phosphor using $Al^{3+}$ and $Ga^{3+}$ as sensitizer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.483-484
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• 2006

$Eu^{3+}$와 $Pr^{3+}$이 첨가된 $SrTiO_3$형광체를 고상반응법으로 제조하였다. $SrTiO_3:Pr$형광체는 $^3P_J(J=0,1,2){\rightarrow}^3H_4$에 의한 490nm 부근의 녹색발광과 $^1D_2{\rightarrow}^3H_4$에 의한 618nm 의 적색발광이 동시에 나타났다. $SrTiO_3:Eu$형광체는 $SrTiO_3:Pr$형광체와 달리 $^5D_0{\rightarrow}^7F_1$에 의한 583nm와 $^5D_0{\rightarrow}^7F_2$에 의한 610nm의 적색발광만 각각 관찰되었다. $SrTiO_3$의 모체에서 $Eu^{3+}$는 inversion sysmmetry를 가짐으로써 610nm의 electric dipole transition 보다는 583nm의 magnetic dipole transition이 강하게 일어났다.

• Journal of the Korean Ceramic Society
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• v.28 no.4
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• pp.261-268
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• 1991

The dielectric properties and microstructure of SrTiO3-based grain boundary layer (GBL) capacitor were investigated, and SrTiO3 GBL capacitor was made by penetrating the Frit (PbO-Bi2O3-B2O3 system). The Nb2O5-doped SrTiO3 ceramics were fired for 4-hours, at 145$0^{\circ}C$ in H2-N2 atomsphere to get semiconductive ceramics. The grain size of SrTiO3 sintered at reduction atmosphere had increased as the amount of Nb2O5 increases and then decreased as the amount of Nb2O5 exceeded 0.2 mole%. Insulating reagents which contained PbO-Bi2O3-B2O3 system frit and oxide mixture were printed on the each semiconductive ceramics and fired at varying temperature and for different holding time. The optimum dielectric properties could be obtained by second heat treatment at 110$0^{\circ}C$ for 1 hour, when frit paste was printed. A SrTiO3-based GBLC had the apparent permitivity of about 3.2$\times$104, the dielectric loss of 0.01~0.02 and the stable temperature coefficient of capacitance. The influence of frit paste on dielectric properties was similiar to that of oxide paste but the stability of temperature property of capacitance was improved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.8-11
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• 1997

This study makes SrTiO$_{3}$ with nonpolarity among ferroelectrics by RF sputtering as dielectric layer, produces thin film of Si/SrTiO$_{3}$ and Si/Ti/SrTiO$_{3}$ of MOS structure using Ti as buffer layer, measures and examines the electrical features with optical refractive index, absorption rate, permittivity, photon energy and as a result, ferroelectrics oscillation occurrs by the interaction within a film by light temperature and the absorption of thin film with Ti as buffer layer is increased. It is found that the pea\ulcorner of permittivity value of Ti/SrTiO$_{3}$ thin film has low values and is appeared late and as dipole which is found in dielectric is shown, the experiment satisfies the theory In the nature of permittivity by photon energy, imaginary value is higher and current variation slope of thin film of thickness SrTiO$_{3}$ has lower values in reverse bias.

• Journal of the Korean Ceramic Society
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• v.22 no.1
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• pp.19-24
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• 1985

The synthetic method was studied on the $SrTiO_3$ powder of pure and homogeneous ultra fine particle of $SrTiO_3$. Pure and ultra fine particle was synthesized from $Sr(OH)_2$.$8H_2O$ and Ti(OH) at 3$0^{\circ}C$~9$0^{\circ}C$ in the $N_2$ gas atmosphere.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.6
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• pp.538-542
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• 2005

The structural and microwave dielectric properties of $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics with sintering temperature were investigated. All the sample of the $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics were prepared by conventional miked oxide method and the sintering temperature was $1425\~1500^{\circ}C$. The hexagonal phase of $Mg_4Ta_2O_9$ and the cubic phase of $SrTiO_3$ were coexisted. The porosity of $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics were reduced with increasing sintering temperature. In the case of $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics sintered at $1475^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 14.51, 82,596 GHz and $-3.14\;ppm/^{\circ}C$, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.9
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• pp.810-814
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• 2005

[ $Pb(Zr_{0.2}Ti_{0.8})O_3/SrRuO_3$ ] heteroepitaxial thin films were deposited at various temperatures on single crystal $SrTiO_3$ substrates by pulsed laser deposition and characterized for the microstructural and ferroelectric properties. The $SrTiO_3$ substartes etched by buffered oxide etch $(pH{\thickapprox}5.8)$ solution for 20s followed by the thermal annealing at $1000^{\circ}C$ for 1h showed the terrace ledges with a 0.4nm height. The $SrRuO_3$ bottom electrodes with a thickness of 52nm grown on $SrTiO_3$ single crystal also exhibit a terrace ledge similar to that of $SrTiO_3$. The PZT thin films were grown with an epitaxial relationship and showed typical P-E hysteresis loops shown at the epitaxial films. The 56nm thick-PZT films deposited at $650^{\circ}C$ exhibit a remanent polarization $(p_r)$ of $80{\mu}C/cm^2$ and a coercive field $(E_c)$ of 160kV/cm.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.525-530
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• 2011

We investigated the electrical properties the starting material and sintering condition on the laminated PTC thermistor for micro circuit protection. The influences of $BaTiO_3$ powder with the 0.3 and 0.45 ${\mu}m$ size and the electrical characteristics (Ba,Sr)$TiO_3$ sintered at 1350~1400$^{\circ}C$ for 2 h in a reducing atmosphere (1% $H_2/N_2$). The sintered (Ba,Sr)$TiO_3$ was increased pore and the grain size was decreased according to increasing Sr additions. In relative permittivity, the phase transition temperature of (Ba,Sr)$TiO_3$ was decreased for 2.5$^{\circ}C$ according to increasing 0.01 mole Sr additions, and the phase transition dose not appeared about 0.3 mole Sr addition. The (Ba,Sr)$TiO_3$ was show the low resistance from 0.01 mole to 0.05 mole by Sr addition, regardless of sintering temperature. The (Ba,Sr)$TiO_3$ was show $10^2$ jump order at 0.1 and 0.2 mole Sr addition, and PTCR of the sintered $(Ba_{0.7}Sr_{0.3})TiO_3$ does not appeared about 0.3 mole Sr addition, regardless of the sintering temperature and starting material size.