• 한국세라믹학회지
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• 제23권6호
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• pp.45-51
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• 1986

$SrTiO_3$ reaction mechanism formed from $TiCl_4$ and $SrCl_2$ solution by direct-wet-process was studied. Through this study it is identified that crystalline $SrTiO_3$ is formed above pH 13.8 amorphous $SrTiO_3$ above pH7 and crystallization temperature of amorphous $SrTiO_3$ is at 37$0^{\circ}C$. the final products are composed of 60% crystalline $SrTiO_3$ and 40% amorphous $SrTiO_3$ The amorphous $SrTiO_3$ is identified with the IR absorption spectrum of Sr-Ti-O by FT-IR spectrometer. Under pH 7 gelationus metatitanate (H2TiO3) is formed from TiCl4 but above pH7 the activity by the formation of metatitnic acid ion $[TiO_3]^{2-}$ is so high that $SrTiO_3$is formed more easily through the reaction with $Sr^{2+}$.

• 한국세라믹학회지
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• 제37권10호
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• pp.1008-1013
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• 2000

SrTi $O_3$(001) 단결정 기판 위에 졸-겔 스핀코팅으로 $SrBi_2(Ta,Nb)_2O_9$ 박막을 도포하고 그 결정화 과정을 고온 X-선 회절분석 (HTXRD)으로 추적하면서 Pt(111)/Ti/ $SiO_2$/Si 위에 성장한 박막과 비교하였다. SrTi $O_3$(001) 단결정 기판 위에 도포된 $SrBi_2Nb_2O_{9}$ 박막은 fluorite-like phase와 같은 transient phase를 거치지 않고 곧바로 순수한 $SrBi_2Nb_2O_9$ 상으로 결정화가 시작되었으며 결정화가 시작되는 온도인 ${\sim}540^{\circ}C$부터 c축 배향성장하였다. 또한 $SrB i_2(Ta,Nb)_2O_9$ 박막은 Ta/Nb 비에 관계없이 $SrTiO_3$(001) 위에서 모두 $(00{\ell})$로 배향되었으며, 코팅 횟수가 늘어나 필름의 두께가 증가함에 따라 c축 배향성은 미세한 감소를 보였다. $SrBi_2Nb_2O_9/SrTiO_3$단면을 TEM으로 관찰한 결과 $SrBi_2Nb_2O_9$은 대체로 불규칙한 크기의 다결정체로 되어 있었으나 계면 부근에서는 [001]$_{SBN}$//[001]$_{SrTi}$ $O_3$/, [100]$_{SBN}$//[100]$_{SrTi}$ $O_3$/라는 결정학적 관계를 가지며 에피탁샬 성장했음을 알 수 있었다.있었다.

• 한국세라믹학회지
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• 제20권1호
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• pp.43-48
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• 1983

The formation of strontium titanate from several molar $SrCO_3$ and $TiO_2$ mixtures was studied in air and $CO_2$ gas Mixtures of $SrCO_3$ and $TiO_2$ were heated in air at 400-$600^{\circ}C$ DTA-TG was used to obtain thermal histories of simples heated in air and $CO_2$ gas. X-ray diffraction analysis was used to determine both the phase composition and the amounts of each phase present. The phase relationship of various compounds $SrTiO_3$, $Sr_2TiO_4$, $Sr_2Ti_3O_7$ and $Sr_4Ti_3O_{10}$ formed by the sintering in each composition was shown by the calibration curves. High temperature X-ray analysis was used to determine both the formation process and deformation process of each products. Small amount of SrTiO3 is formed first at the surface af contact SrTiO3 reacts with $SrCO_3$ to form Sr2TiO4 this is affected on the $CO_2$ pressure.

• 한국재료학회지
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• 제18권7호
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• pp.389-393
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• 2008

Nano-sized $TiO_2$-60 wt% SrO composite powders were synthesized by a sol-gel method using titanium isopropoxide and $Sr(OH)_2\;{\cdot}\;8H_2O$ as precursors. 3, -5, -7 wt%Ag spot-coated $TiO_2$-60 wt% SrO composite powders were synthesized by a Ag electroless deposition method using $TiO_2$-60 wt% SrO composite powders calcined at $1050^{\circ}C$, which mainly exhibited the $SrTiO_3$phase. However, a small number of rutile $TiO_2$, $Sr_2TiO_4$ and $SrO_2$ phases were also detected. In the Ag spot-coated powders synthesized by electroless deposition, nano-sized particles about 5-25 nm in diameter adhered to the $TiO_2$-60 wt% SrO composite powders. The photocatalytic activity of Ag spot-coated $TiO_2$-SrO and $TiO_2$-SrO composite powders for degradation of phenol showed that all of $TiO_2$-SrO composite powders were highly active under UV light irradiation. 7 wt%Ag spot-coated $TiO_2$-60wt.%SrO composite powders had a relatively higher photocatalytic activity than did $TiO_2$-SrO composite powders under visible light.

• 한국세라믹학회지
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• 제21권2호
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• pp.165-173
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• 1984

It is desirable to establish reliable synthetic methods for electro-ceramic materials. To synthesize $SrTiO_3$ in this study direct solid state reactions and wet chemical processes were used. Previous study of $SrTiO_3$ synthesis included oxalated-method($SrTiO(C_2O_4)_2$.$4H_2O$) co-precipitation$(SrCO_3+TiO(OH)_2)$ and direct solid state reaction$(SrCO_3+TiO(OH)_2)$ The methods in question lead to intermediate inclusion during the reactions and less controllable in particle sizes of $SrTiO_3$. To obtain highly pure $SrTiO_3$ so-called "direct wet process method" was added in this investigation. In the study the "direct wet process" was for the first time applied to synthesize chemically pure and fine particle $SrTiO_3$. $SrCl_2$ and $TiCl_4$<\ulcornerTEX> at KOH solution at room temperature to 10$0^{\circ}C$ precipitated $SrTiO_3$ The particle size increased as temperature increased.mperature increased.

• 한국세라믹학회지
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• 제28권3호
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• pp.215-224
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• 1991

The synthesis of SrTiO3 powders having high purity and homogeneous submicron particle size was attempted by the oxalate method. The microstructure and dielectric properties of SrTiO3 based boundary layer capacitor (BLC) were investigated. Strontium titanyl oxalate[SrTiO(C2O4)2.4H2O] was prepared from the mixing solution of (Sr, Ti) using oxalic acid(H2C2O4) as a precipitating agent at 8$0^{\circ}C$. The crystalline SrTiO3 powder was obtained by thermal decomposition of the precipitate above $600^{\circ}C$. The crystalline SrTiO3 powder containing Nb2O5 as a dopant, TiO2 and SiO2 as additives was sintered at 1360~144$0^{\circ}C$ in the reducing atmosphere to get semiconductive SrTiO3. Insulating material containing PbO-Bi2O3-B2O3 frit was printed on the sintered semiconductive SrTiO3 and fired at 120$0^{\circ}C$ for 2h to get the grain boundary diffusion.

• 한국세라믹학회지
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• 제38권3호
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• pp.225-230
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• 2001

저전압용 형광체로 주목받고 있는 SrTiO$_3$:Pr,Al 형광체를 고상반응법으로 제조하였다. 부활성체 Al이 23 mol% 첨가되었을 때 SrTiO$_3$:Pr 형광체는 최대 발광 강도를 보여주었다. 최대 발광 강도를 보인 형광체에 대해 제한시야회절상과 투과전자현미경을 이용하여 SrTiO$_3$:Pr,Al 적색 형광체내 2차상 형성에 대한 연구를 행하였고 또한 에너지 분산 분광 분석을 행하여 SrTiO$_3$:Pr,Al 형광체내 주입된 부활성제 Al의 함량을 결정하였다. 제한시야회절상의 결과에 의하면 SrTiO$_3$:Pr,Al 적색 형광체내에 단사정 SrAl$_2$O$_4$, 삼사정 Ti$_4$O$_{7}$, 육방정 SrAl$_{12}$O$_{19}$가 2차상으로 존재함을 보여 주었다. 에너지 분산 분광 분석 결과 부활성제 Al의 함량 중 일부는 SrTiO$_3$:Pr,Al 적색 형광체 격자에 고용되고 일부 Al은 SrAl$_{12}$O$_{19}$와 SrAl$_2$O$_4$의 2차상을 형성하는데 소모됨을 보여주었다.주었다.

• The Korean Journal of Ceramics
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• 제5권2호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.194-196
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• 2004

$BaTiO_3/SrTiO_3$ heterolayered thick films on the $Al_2O_3$ substrate by screen printing method with stacking periodicity. The stacking periodicity of $BaTiO_3/SrTiO_3$ heterolayer structure was varied from $(BaTi_O_3)_1/(SrTiO_3)_1$ to $(BaTi_O_3)_3/(SrTiO_3)_3$. The total thickness of the $BaTiO_3/SrTiO_3$ films was about $120{\mu}m$. There was an interdiffusion at the interface of the $BaTiO_3$ and $SrTiO_3$ layers. The dielectric constant of $BaTiO_3/SrTiO_3$ heterolayered thick films was increased with decreasing stacking periodicity of the $BaTiO_3/SrTiO_3$. The dielectric constant of the ($(BaTi_O_3)_1/(SrTiO_3)_1$ herterolayered thick films was about 1780.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권7호
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• pp.344-348
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• 2006

The effect of x on microwave dielectric properties of the $(1-x)Mg_4Ta_2O_9-x(TiO_2,\;CaTiO_3,\;SrTiO_3)$ ceramics for microwave components were investigated. All spcecimens prepared by the conventional mixed oxied method and sintered at $1450^{\circ}C$. Microwave dielectric properties of the $(1-x)Mg_4Ta_2O_9-xTiO_2$ ceramics were influenced by $MgTi_2O_5$ phase. Also the microwave dielectric properties of the $(1-x)Mg_4Ta_2O_9-x(TiO_2,\;CaTiO_3,\;SrTiO_3)$ ceramics were dominated with an addition of $CaTiO_3\;and\;SrTiO_3$. The dielectric constant $(\varepsilon_r)$, quality factor $(Q{\times}f_r)$ and temperature coefficient of the resonant frequency $(TCRF,\;\tau_f)$ of the $(1-x)Mg_4Ta_2O_9-x(TiO_2,\;CaTiO_3,\;SrTiO_3)$ ceramics were $12.96\sim70.98,\;5,132\sim186,410GHZ$ and $-35.82\sim+75.96ppm/^{\circ}C$, respectively, and depend on x and addition materials.