• Title/Summary/Keyword: Strontium ferrite

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The Effect of Curie Point Annealing on Electrophysical Phenomena at the Magnetized SrO 6$Fe_{2}O_{3}$ Ceramics/Electrolyte Interface (자화된 SrO 6$Fe_{2}O_{3}$ 세라믹스와 전해질 계면의 전기물리적 현상에 미치는 Curie점 열처리 효과)

  • 천장호;손광철;라극환
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.7
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    • pp.63-68
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    • 1994
  • The Curie point annealing effects on electrophysical phenomena at the magnetized strontium ferrite(SrO$\cdot$ 6$Fe_{2}O_{3}$) ceramics electrode/10$^{-3}$M KC1 aqueous electrolyte interfaces have been studied using cyclic voltammetric, normal pulse voltammetric, chronocoulometric, and electrochemical impedance techiques. After the Curie point annealing the magnetic flux densities of the speciment was decreased from 900-1100 gauss to 1-2 gauss, i.e. demagnetized. The real component of interfacial impedance was decreased from 7280-7320 ohm to 790-830 ohm. The adsorption and the charge on the electrical double layer was increased from 0 $\mu$C to -58 $\mu$C. The Curie point annealing and the related electrical double layer effect can influence not only the electrophysical properties of the strontium ferrite ceramics electrode itself but also the electrochemical phenomena at the electrode interface. This experimental results suggest that the Curie point annealing and the related electrical double layer effect can be applied to electrochemical magnetic sensors.

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Characterization and Electrochemical Performance of Composite BSCF Cathode for Intermediate-temperature Solid Oxide Fuel Cell

  • Kim, Yu-Mi;Kim-Lohsoontorn, Pattaraporn;Bae, Joong-Myeon
    • Journal of Electrochemical Science and Technology
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    • v.2 no.1
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    • pp.32-38
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    • 2011
  • The composite barium strontium cobalt ferrite (BSCF) cathodes were investigated in the intermediate temperature range of solid oxide fuel cells (SOFCs). The characteristics and electrochemical performances of composited BSCF/samarium doped ceria (SDC); BSCF/gadolinium doped ceria (GDC); and BSCF/SDC/GDC were compared to single BSCF cathode. The BSCF used in this study were synthesized using glycine nitrate process and mechanically mixing was used to fabricate a composite cathode. Using a composite form, the thermal expansion coefficient (TEC) could be reduced and BSCF/SDC/GDC exhibited the lowest TEC value at $18.95{\times}10^{-6}K^{-1}$. The electrochemical performance from half cells and single cells exhibited nearly the same trend. All the composite cathodes gave higher electrochemical performance than the single BSCF cathode (0.22 $Wcm^{-2}$); however, when two kinds of electrolyte were used (BSCF/SDC/GDC, 0.36$Wcm^{-2}$), the electrochemical performance was lower than when the BSCF/SDC (0.45 $Wcm^{-2}$) or BSCF/GDC (0.45 $Wcm^{-2}$) was applied as cathode ($650^{\circ}C$, 97%$H_2$/3%$H_2O$ to the anode and ambient air to the cathode).

Effects of Particle Size Distribution on The Magnetic Properties of Hexagonal Sr-Ferrite (육방정 Si-폐라이트의 자기적 특성에 미치는 입도 분포의 영향)

  • Song, Chang-Yul;Shin, Yong-Deok
    • Proceedings of the KIEE Conference
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    • 1994.07b
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    • pp.1314-1316
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    • 1994
  • $0.36[wtx]Sio_2$ and $0.1[wtx]H_3BO_3$ were added to strontium ferrite magnets of the magnetoplumbite phase SrO $5.7Fe_2O_3$. This experiment was carried out to investigate the effects of particle size distribution as a function of milling time(20,30,40,50,60,70 hours) on the magnetic properties of SrO $5.7Fe_2O_3$ ferrite magnet. The B-H Curve, density and the degree of orientation were measured. The optimal conditions of making magnets and properties of a typical sample are the following : The milling time was 60 hours. Magnetic and physical properties are $B_r$=4000[G], $_BH_c$=3330[Oe], $_IH_c$=3525[Oe], (BH)max=3.786 [MGOe], density= $5.0063g/cm^2$, orientation factor f=0.813.

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A Study on the Effect of $La_2O_3$ on Characteristics of $Sr{\cdot}nFe_2O_3$ ($Sr{\cdot}nFe_2O_3$에 미치는 $La_2O_3$의 영향에 관한 연구)

  • Oh, Eung-Choul;Cho, Jae-Won;Moon, Hyun-Wook;Shin, Yong-Jin
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1992.11a
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    • pp.31-33
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    • 1992
  • This paper is studies the addition effects of $La_2O_3$ on the magnetic properties of Sr ferrite. Compositions were chosen according to the formula $[SrO{\cdot}nFe_2O_3]_{100-x}(La_2O_3)_x$. where n was varied between 5.8~6.1 and x between 0~3. The composition of the best value $(BH)_{max}$=1.48MGOe was n=6(stoichiometric composition) and x=2 at $La_2O_3$ addition. This value was higher than that of ordinary isotropic strontium ferrite.

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Oxygen Permeation Properties and Phase Stability of Co-Free $La_{0.6}Sr_{0.4}Ti_{0.2}Fe_{0.8}O_{3-{\delta}}$ Oxygen Membrane

  • Kim, Ki-Young;Park, Jung-Hoon;Kim, Jong-Pyo;Son, Sou-Hwan;Park, Sang-Do
    • Korean Membrane Journal
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    • v.9 no.1
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    • pp.34-42
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    • 2007
  • A perovskite-type ($La_{0.6}Sr_{0.4}Ti_{0.2}Fe_{0.8}O_{3-{\delta}}$) dense ceramic membrane was prepared by polymerized complex method, using citric acid as a chelating agent and ethylene glycol as an organic stabilizer. Effect of Ti addition on lanthanum-strontium ferrite mixed conductor was investigated by evaluating the thermal expansion coefficient, the oxygen flux, the electrical conductivity, and the phase stability. The thermal expansion coefficient in air was $21.19\;{\times}\;10^{-6}/K$ at 473 to 1,223 K. At the oxygen partial pressure of 0.21 atm ($20%\;O_2$), the electrical conductivity increased with temperature and then decreased after 973 K. The decrement in electrical conductivity at high temperatures was explained by a loss of the lattice oxygen. The oxygen flux increased with temperature and was $0.17\;mL/cm^2{\cdot}min$ at 1,223 K. From the temperature-dependent oxygen flux data, the activation energy of oxygen ion conduction was calculated and was 80.5 kJ/mol at 1,073 to 1,223 K. Also, the Ti-added lanthanum-strontium ferrite mixed conductor was structurally and chemically stable after 450 hours long-term test at 1,173 K.

A Study on the Effects of first and second additives Magnetic Characteristics of Anisotropic $SrO-5.7Fe_2O_3$. (1,2차 첨가제가 이방성 $SrO-5.7Fe_2O_3$의 자기적 특성에 미치는 효과)

  • Song, Joon-Tae;Shin, Yeong-Duck;Jeong, In-Young;Jin, Hong-Bum
    • Proceedings of the KIEE Conference
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    • 1990.07a
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    • pp.239-242
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    • 1990
  • The effect of $CaCo_3$, $SrCo_3$, $SiO_2$ and $H_3BO_3$ in the range of 0.1-1.0 wt% on strontium ferrites consisting of the magnetoplumbite phase $SrO-5.7Fe_2O_3$ were investigated. The hysteresis loop, density, demagnetization curve and the intrinsic coercive force were measured on anisotropic ferrite. The particle diameter and 0.5(wt%) of second additive $CaCo_3$ is particularly important for the properties of anisotropic ferrite. When the particle diameter is decreased from 1.98(${\mu}m$) to 1.07(${\mu}m$), the remance is increased from 2900 to 4010(G) and the coercive force from 2150 to 2850(Oe) at a sintering temperature 1230 ($^{\circ}C$). Remance Br(G), coercleve force(Oe) and maximum energy product of sample A-16 are87(%), 56(%), 67(%) of S-W model theoretical value.

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Long-term Testing and Analysis of a ScSZ/LaSrCuFe Cell

  • Wackerl, Jurgen;Peck, Dong-Hyun;Markus, Torsten
    • Journal of the Korean Ceramic Society
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    • v.45 no.12
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    • pp.788-795
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    • 2008
  • An electrolyte supported SOFC cell was tested at $800^{\circ}C$ in air for 3600 h with an applied current density of $200\;mA/cm^2$ to examine possible cathode degradation issues. A scandium- stabilized zirconia (ScSZ) with additional manganese doping (ScSZ: Mn) was used as electrolyte. A strontium and copper-doped lanthanum ferrite (LaSrCuFe) and platinum were used as cathode and quasi-anode material, respectively. The DC resistance was logged over the complete testing period. Additionally, impedance spectroscopy was used from time to time to track changes of the cell in-situ. Post-test analysis of the cell using methods like scanning electron microscopy imaging and other electrochemical testing methods allow the identification of different degradation sources. The results indicate a promising combination of electrolyte and cathode material in terms of chemical compatibility and electrical performance.

Magnetic Properties of Mn and La-Mn Substituted Strontium Ferrite (Mn 및 La-Mn 치환 Sr 페라이트의 자기적 특성 변화)

  • 장세동;김종오;김종희
    • Journal of the Korean Magnetics Society
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    • v.11 no.6
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    • pp.267-271
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    • 2001
  • These experiments were carried out to examine the effects of elemental substitution of Mn and La-Mn on Sr-ferrite. The calcined properties for the Mn and La-Mn substitution were examined, and the sintered magnetic properties were compared with the stoichiometric condition. The magnetic properties of calcined SrM and (La-Mn)$_{0.3}$-SrM composition were as follows, respectively; M$_{s}$ : 61.06 emu/g, $_{i}$H$_{c}$ : 4.45 kOe and M$_{s}$ : 61.06 emu/g, $_{i}$H$_{c}$ : 4.46 kOe. Also, the sintered ferrite magnets of Mn$_{0.3}$-SrM and [(La-Mn)$_{0.3}$-SrM exhibited a similar properties to the stoichiometric composition but the coercivity of (La-Mn)$_{x}$-SrM was decreased rapidly with x=0.5.

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Studies on the Chemical and Physical Properties of Perovskite-Type Ferrites Containing Strontium (스트론티움을 포함하는 페롭스카이트형 페라이트의 화학적·물리적 성질에 관한 연구)

  • Lee, Eun-Seok;Yo, Chul-Hyun
    • Applied Chemistry for Engineering
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    • v.4 no.2
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    • pp.342-348
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    • 1993
  • At 1473 K under atmospheric pressure, the homogeneous samples of the $Sm_{1-x}Sr_xFe^{3+}{_{1-t}}Fe^{4+}{_t}O_{3-y}$ ($0.00{\leq}x{\leq}1.00$) ferrite system were prepared. With the increase in x value, the amount of $Fe^{4+}$ ion increased and the crystallographic structure was changed from orthorhombic symmetry to cubic symmetry. The electrical conductivity at constant temperature sharply increases and the activation energy decreases with the increase of $Fe^{4+}$ ion. $M{\ddot{o}}ssbauer$ spectrum of the sample x=0.00 shows six-line pattern indicating the presence of $Fe^{3+}$ ion in the octahedral sites.

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