• Title/Summary/Keyword: Lanthanum-140

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Measurement of the Flow Characteristics and Vertical Density Profile of Catalyst in RFCCU by Radioisotope (방사성동위원소를 이용한 정유설비 내 촉매유동 특성 및 수직밀도 분포 측정)

  • Moon, Jinho;Kim, Jong Bum;Park, Jang Guen;Jung, Sung-Hee
    • Journal of Radiation Industry
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    • v.5 no.4
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    • pp.317-323
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    • 2011
  • Radioisotopes have been widely used throughout industry to optimize processes, solve problems and improve product quality. A gamma scanning technique using radiation via sealed source (Co-60) was carried out in order to investigate vertical density profile of catalyst regenerator of RFCCU. Also through the radiotracer experiments, the flow characteristics of catalyst was measured. The catalyst samples were irradiated with neutron in HANARO reactor to produce lanthanum-140 to be used as radiotracer for tracing the catalyst itself in catalyst regenerator of RFCCU. The radiotracer was monitored around the catalyst regenerator using collimated NaI scintillation detectors. The results of the experiments were used to diagnose the performance of the RFCCU.

Effect of grinding on Lanthanum Aluminate Ceramics (분쇄효과가 $LaAlO_3$세라믹스에 미치는 영향)

  • 조정호;최상수;김강언;정수태
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.07a
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    • pp.705-708
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    • 2001
  • The effect of grinding on the synthesis of LaAO$_3$ceramics was investigated. The mixture ground by plantary ball mill showed 70nm particle size (wet ball mill or unground=0.5 $\mu$m). Monophase LaAlO$_3$powders were formed when ground samples were heated at 100$0^{\circ}C$, however unground samples required temperatures above 130$0^{\circ}C$. Density of the ground samples sintered at 140$0^{\circ}C$ showed 98.3% of theoretical density (unground=93.5% at 150$0^{\circ}C$). Dielectric constant of the ground samples($\varepsilon$r=22.4) showed higher values than that of the unground samples($\varepsilon$r=20.32). Temperature coefficient of capacitance($\tau$$_{c}$) and dielectric loss (tan$\delta$) of the ground samples were similar to those of unground samples.s.

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Thermal Decomposition and Sintering Characteristics of Cr-Deficient $(La,Ca)CrO_3$ (크롬부족 (란탄, 칼슘)크로마이트의 열분해과정 및 소결특성)

  • 이상기;조성걸
    • Journal of the Korean Ceramic Society
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    • v.34 no.11
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    • pp.1182-1186
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    • 1997
  • La0.8Ca0.2Cr0.98O3 powder was prepared using the modified Pechini process. Various crystalline phases formed during thermal decomposition were investigated. (La,Ca)CrO4 phase, first formed from the precursor, was transformed to (La,Ca)CrO3 and CaCrO4 above 80$0^{\circ}C$, which remained up to 110$0^{\circ}C$. However, only (La,Ca)CrO3 phase consisting of orthorhombic and intermediate rhombohedral polymorphs was observed after sintering at 125$0^{\circ}C$. The specimens sintered at 140$0^{\circ}C$ exhibited 98% of relative density and rather wide grain size distribution with average grain size of 3-4 ${\mu}{\textrm}{m}$. Densification and grain growth of the specimens observed above 125$0^{\circ}C$ were presumably attributed to liquid phase sintering resulted from melting of Ca3(CrO4)2 phase.

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Fabrication, Magnetic and Magnetoresistive Properties of Bi-Doped Lanthanum Manganites (Bi 첨가 란탄 망가나이트의 제조, 자기 및 자기저항 특성)

  • 김덕실;조재경
    • Journal of the Korean Magnetics Society
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    • v.9 no.5
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    • pp.239-244
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    • 1999
  • Bi-doped lanthanum magnetics $(La_{0.67-x}Bi_xCa_{0.33}MnO_3(x\;=\;0,\; 0.04,\; 0.1,\; 0.2))$ samples have been prepared by standard ceramic process. The crystallinity and microstructures of the samples have been investigated by x-ray diffractometry and optical microscopy, respectively. The magnetic and magnetoresistive properties of the samples have been measured by vibrating sample magnetometery and van der Pauw method, respectively, at the temperatures ranging of 100 K~300 K with applied magnetic field of 0.4~0.5 T. Good crystallinity and high Curie temperature (275 K) have been obtained for the Bi-doped samples with small dosage (x = 0.04, 0.1) even they were sintered at 120$0^{\circ}C$, which is about 20$0^{\circ}C$ lower than normal sintering temperature of 140$0^{\circ}C$. The Bi-doped samples with the small dosage showed lower relative electrical resistivity and higher magneto-resistive ratio compared to the undoped sample in the most temperatures measured. The Bi-doped samples also exhibited large magnetoresisitve ratio (maximum of 15% for x = 0.1) at room temperature even under a weak magnetic field of 0.4 T.

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