• Korean Journal of Materials Research
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• v.3 no.4
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• pp.410-421
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• 1993

Phase equilibria and reaction paths of the superconducting phases and other compatible phases at $850^{\circ}C$ in the Bi-Sr-Ca-Cu-O system were studied. $Bi_2O_3$ was added to $Sr_2CaCu_2O_x$ by 5% up to 40 mole% Bi in the pseudo-binary $Bi_2O_3-(Sr_2CaCu_2O_x)$ system and the heat treated samples were analysed using XRD. SEM, EDS. and DT A. When Bi contents were greater than 35 mole% Bi, liquid phase was formed which was compatible with $Bi_2Sr_2CaCu_2O_8$ phase. The m.p. of $Bi_2Sr_2CaCu_2O_8$ phase decreased as the content of (Sr+Ca)decreased. $Bi_{2+x}Sr_2CaCu_2O_8$ phase first segregated out of liquid phase around $Bi_2Sr_2CaCu_2O_8$ phase during cooling of liquid phase.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.1927-1928
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• 2014

• Transactions on Electrical and Electronic Materials
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• v.15 no.5
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• pp.249-252
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• 2014

The aim of this work is to investigate the effect of $Ca_xSr_{2-x}$ and activator on the structural and luminescent properties of green-emitting $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ nano phosphor. Using urea as fuel and ammonium nitrate as oxidizer, $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ has been successfully synthesized, using a combustion method. The particles were found to be small, spherical and of round surface. SEM imagery showed that the phosphors particles are of nanosize. The $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ emission spectrum for 360 nm excitation showed a single band, with a peak at 490 nm, which is a green emission. The highest luminous intensity was at $1,000^{\circ}C$, which was obtained when the $Eu^{2+}$ content (y) was 0.05. The results support the application of $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ phosphor as a fluorescent material for ultraviolet light-emitting diodes (UV-LEDs). Characteristics of the synthesized $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ phosphor were investigated by means of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and photoluminescence (PL) detection.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.284-287
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• 2001

Multi-pole anisotropic Sr-ferrite sintered magnets has been studied by powder injection molding under applied magnetic field. The orientation of anisotropic Sr-ferrite powders higher than 80% during injection molding is achieved at the following conditions; apparent viscosity lower then 2500 poise in 1000 $sec^{-1}$ shear rate and applied magnetic field higher then 4 kOe. For the high fluidity and strength of injection molded compact, and the effective binder removal without defects during solvent extraction and thermal debinding, the optimum multi-binder composition is paraffin wax(PW)/carnauba wax(CW)/HDPE = 50/25/25 wt%. The rate of binder removal is proportional to the mean particle size of Sr-ferrite powders whereas it is inversely proportional to the content of Sr-ferrite powders and the sample thickness. The high magnetic properties of Sr-ferrite sintered magnets are; 3.8 kG of remanent flux density, 3.4 kOe of intrinsic coercivity, and 1.2 kG of surface flux density (l-mm-thick) in the direction of applied magnetic field.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.360-363
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• 2006

We synthesized $(La,\;Sr)MnO_{3+{\delta}$ as a cathode for SOFC by glycine nitrate process(GNP) and knew the different properties of $(La_{1-x}Sr_x)MnO_3$ by using nitrate solution and oxide solution as starting material. In case of using nitrate solution as a starting material, main crystal phase peak of $LaMnO_3$ increased as Sr content added up and a peak of $Sr_2MnO_4\;and\;La_2O_3$ was showed as a secondary phase. We added Mn excess to control a crystal phase. In this case, the electrical conductivity had a high value 210.3S/cm at $700^{\circ}C$ On the other side, when we used oxide solution as a starting material, we found main crystal phase of $LnMnO_3$ to increase as Sr content added up and a peak of $La_2O_3$ as a secondary phase. Similary, we added Mn excess to control a crystal phase in this case. We knew $(La,\;Sr)MnO_3$ powder to sinter well and the electrical conductivity of the sintered body at $1200^{\circ}C$ for 4hrs was 152.7s/cm at $700^{\circ}C$. The sintered $(La,\;Sr)MnO_3$ powder at $1000^{\circ}C$ for 4hrs got the deoxidization peak, depending on the temperature md in case of using nitrate solution as a start ing material the deoxidization peak was showed at $450^{\circ}C$ which is lower than used a oxide solution as a starting material. As a result, when $(La,\;Sr)MnO_3$ powder was synthesized to add Mn excess and to use nitrate solution as a starting material, we found it to have the higher deoxidization property and considered it as a cathode for m properly. And we found it to have different electrical conduct ivity the synthesized $(La,\;Sr)MnO_3$ powder by using different start ing materials like nitrate solution and oxide solution which influence a sintering density and crystal phase.

• Journal of the Korean Ceramic Society
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• v.44 no.1 s.296
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• pp.52-57
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• 2007

We synthesized $(La_{1-x}Sr_x)MnO_3$ as a cathode for SOFC by glycine nitrate process (GNP) and knew the different properties of $(La_{1-x}Sr_x)MnO_3$ by using nitrate solution and oxide solution as a starting material. In case of using nitrate solution as a starting material, main crystal phase peak of $LaMnO_3$ increased as Sr content added up and a peak of $Sr_2MnO_4\;and\;La_2O_3$ was showed as a secondary phase. We added Mn excess to control a crystal phase. In this case, the electrical conductivity had a high value 210.3 S/cm at $700^{\circ}C$. On the other side, when we used oxide solution as a starting material, we found main crystal phase of $LaMnO_3$ to increase as Sr content added up and a peak of $La_2O_3$ as a secondary phase. Similary, we added Mn excess to control a crystal phase in this case. We knew $(La,Sr)MnO_3$ powder to sinter well and the electrical conductivity of the sintered body at $1200^{\circ}C$ for 4 h was 152.7 S/cm at $700^{\circ}C$. The sintered $(La,Sr)MnO_3$ powder at $1000^{\circ}C$ for 4 h got the deoxidization peak, depending on the temperature and in case of using nitrate solution as a starting material, the deoxidization peak was showed at $450^{\circ}C$ which is lower than used a oxide solution as a starting material. As a result, when $(La,Sr)MnO_3$ powder was synthesized to add Mn excess and to use nitrate solution as a starting material, we found it to have the higher deoxidization property and considered it as a cathode for SOFC properly. And we found it to have different electrical conductivity the synthesized $(La,Sr)MnO_3$ powder by using different starting materials like nitrate solution and oxide solution which influence a sintering density and crystal phase.

• Progress in Superconductivity
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• v.6 no.1
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• pp.37-40
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• 2004

We investigated the effects of impurity doping on the electrical transport and magnetic properties of TEX>$(Ru, Sn)(Sr, La)<_2$$EuCeCu_2$$O_{z}$ samples. We found that Sn substitution fur Ru causes a significant decrease of the volume fraction of ferromagnetic phase, as well as a decrease of the temperature where the ferromagnetic component is observed. La substitution for Sr leads to an increase of the magnetic ordering temperature with a moderate change of ferromagnetic component. The experimental results are discussed in conjunction with the structural data, transport properties and a possible change of oxygen content.

• Journal of the Korean Ceramic Society
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• v.33 no.1
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• pp.35-40
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• 1996

The influence of grain boundary on the electrical properties of WO3-doped SrTiO3 ceramics has been investi-gated. From the result resistivity and capacitance of grains and boundaries were obtained by employing impedance spectrocopy. And the temperature dependance of capacitance of WO3-doped SrTiO3. was influenced directly by the variation of grain boundary capacitance. It was also found by impedance spectroscopy that the dispersion frequency characteristics showed discernibly that the resistivity of the specimen varied with WO3 content.

• Journal of the Korean Ceramic Society
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• v.24 no.4
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• pp.321-328
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• 1987

The chemical durability of six alumino fluorophosphate glass samples studied. The composition of glass varied with MgF2 content from 0 to 12.5wt% in 30AlF3-2MgF2-(50-x)MF2-10P2O5(M; Sr, Ba). Samples were maintained in distilled water at 95$^{\circ}C$ from 1 to 100hrs. Weight loss, pH change and leached elements of the solution, and IR transmittance of samples were measured and also their surfaces were observed by SEM. Chemical durabilities of these samples were increased with increasing MgF2 contents. The following various properties were increased rapidly up to 10 hours after that changed slowly. The sample after leached at 95$^{\circ}C$ during 100 hrs showed 0.5mg/$\textrm{cm}^2$ in weight loss. The pH of leached solution is 6.2 and concentration of Mg, Sr, and Ba element of that leached solution were 24,115 and 125 ppm, respectively. The infrared transmittance of leached sample decreased 7% compare to unleached one. And also SEM photomicrograph and EDS analysis showed that the corrosion of samples were decreased with respect to increasing MgF2 content.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.288-291
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• 2002

An alkoxide-based sol-gel method was used to fabricate $(Pb_{x},Sr_{1-x})$TiO3 (PST) thin films on a Pt/Ti/SiO2/Si substrate, and the dielectric properties of the PST thin films were investigated as a function of the Pb/Sr composition for use in tunable microwave device applications. The dielectric properties of the PST films were strongly dependent on the Pb/Sr ratio. The dielectric constant and dielectric loss of the PST films increased with increasing Pb content, and the figure of merit (FOM) reached a maximum value of 27.5 at a Pb/Sr ratio of 4:6. The tunability increased with increasing Pb content. The dielectric constant, loss factor, and tunability of PST (50/50) thin films were 404, 0.023, and 51.73%, respectively. From the result, the PST films with good dielectric properties are useful candidates for tunable microwave device.