• Title/Summary/Keyword: Praseodymium Oxide

Search Result 8, Processing Time 0.029 seconds

Effect of Cobalt Oxide Addition on Electrical Properties of Praseodymium-based Zinc Oxide Varistors (프라세오디뮴계 산화아연 바리스터의 전기적 특성에 코발트 산화물 첨가의 영향)

  • Nahm, Choon-Woo;Park, Jong-Ah;Yoo, Dae-Hoon;Suh, Hyoung-Kwon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.18 no.10
    • /
    • pp.896-901
    • /
    • 2005
  • The microstructure and electrical properties of praseodymium-based zinc oxide varistors were investigated at various cobalt oxide contents in the range of $0.5{\~}5.0 mol\%$. The ceramic density increased in the range of $5.25{\~}5.55 g/cm^3$ with increasing cobalt oxide content. The varistor doped with cobalt oxide of $1.0 mol\%$ exhibited the highest nonlinearity, with 66.6 in nonlinear exponent and 1.2 $\mu$A in leakage current. The donor concentration, density of interface states, and tamer height were in the range of $(1.06{\~}1.69){\times}10^{18}/cm^3$, $(3.11 {\~}3.56){\times}10^{12}/cm^2$, and 0.80${\~}$1.07 eV, respectively.

Zinc Oxide Varistors with Praseodymium Oxide (Praseodymium계 ZnO 바리스터의 제조 및 미세구조 연구)

  • Soh, J.J.;Han, S.W.;Kim, H.S.;Cho, H.G.;Kim, I.S.
    • Proceedings of the KIEE Conference
    • /
    • 1997.07d
    • /
    • pp.1342-1344
    • /
    • 1997
  • Zinc oxide varistors which contain rare earth metal oxides have been developed. These Varistors are widely used for low voltage surge-protection devices and high voltage arresters for electric power stations. The characteristics of varistors with praseodymium oxide as a principal additive are discussed. A two-phase microstructure with an intergranular phase between the ZnO grains.

  • PDF

A Study on the Stability of Praseodymium-Based Zinc Oxide Varistor with Tittria Additives. (이트리아가 첨가된 프라세오디뮴계 산화아연 바리스터의 안정성에 관한 연구)

  • 남춘우;박춘현
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.11 no.10
    • /
    • pp.842-848
    • /
    • 1998
  • The stability of paraseodymium-based zinc oxide varistor consisting of Zn-Pr-Co-Cr-Y oxide was investigated according to yttria additives under different stress conditons, such as 0.8V\ulcorner\ulcorner/373K/12h and 0.85V\ulcorner\ulcorner/393K/12h. Wholly, all varistor after the stress showed nearly symmetric and stable I-V characteristics. Particularly, in the case of 2.0mol% and 4.0mol% yttria-added varistor showing a good I-V characteristics, the varation rate of varistor voltage were less 1% and that of nonlinear coefficient were about degree of 5%, and what is remarkable, leakage current with increasing stress time during the applied stress was almost constant. It the light of these facts, it is estimated that varistor constituents having 2.0mol% and 4.0mol% yittria, respectively, will be utilized to various application fields.

  • PDF

Characteristics of ZnO Varistors with Praseodymium Oxide

  • Lee, Sang-Ki;Cho, Sung-Gurl;Shim, Young-Jae
    • The Korean Journal of Ceramics
    • /
    • v.5 no.4
    • /
    • pp.357-362
    • /
    • 1999
  • ZnO varistors containing cobalt, praseodymium and calcium oxides were prepared. The current-voltage charcteristics and microstructures of the specimens were investigated with respect to calcium addition and sintering temperature. The potential barrier heights and the carrier densities were estimated from C-V relations. The compatibility of Ag-Pd as an internal electrode for multilayer chip varistor was also examined.

  • PDF

Leaching Kinetics of Praseodymium in Sulfuric Acid of Rare Earth Elements (REE) Slag Concentrated by Pyrometallurgy from Magnetite Ore

  • Kim, Chul-Joo;Yoon, Ho-Sung;Chung, Kyung Woo;Lee, Jin-Young;Kim, Sung-Don;Shin, Shun Myung;Kim, Hyung-Seop;Cho, Jong-Tae;Kim, Ji-Hye;Lee, Eun-Ji;Lee, Se-Il;Yoo, Seung-Joon
    • Korean Chemical Engineering Research
    • /
    • v.53 no.1
    • /
    • pp.46-52
    • /
    • 2015
  • A leaching kinetics was conducted for the purpose of recovery of praseodymium in sulfuric acid ($H_2SO_4$) from REE slag concentrated by the smelting reduction process in an arc furnace as a reactant. The concentration of $H_2SO_4$ was fixed at an excess ratio under the condition of slurry density of 1.500 g slag/L, 0.3 mol $H_2SO_4$, and the effect of temperatures was investigated under the condition of 30 to $80^{\circ}C$. As a result, praseodymium oxide ($Pr_6O_{11}$) existing in the slag was completely converted into praseodymium sulfate ($Pr_2(SO_4)_3{\cdot}8H_2O$) after the leaching of 5 h. On the basis of the shrinking core model with a shape of sphere, the first leaching reaction was determined by chemical reaction mechanism. Generally, the solubility of pure REEs decreases with the increase of leaching temperatures in sulfuric acid, but REE slag was oppositely increased with increasing temperatures. It occurs because the ash layer included in the slag is affected as a resistance against the leaching. By using the Arrhenius expression, the apparent activation energy of the first chemical reaction was determined to be $9.195kJmol^{-1}$. In the second stage, the leaching rate is determined by the ash layer diffusion mechanism. The apparent activation energy of the second ash layer diffusion was determined to be $19.106kJmol^{-1}$. These relative low activation energy values were obtained by the existence of unreacted ash layer in the REE slag.

A Study on the Reaction Characteristics of Rare Earth Oxides with Lithium Oxide in LiCl Molten Salt (LiCl 용융염 중에서 희토류 산화물과 산화리튬의 반응특성에 관한 연구)

  • 오승철;박성빈;김상수;도재범;박성원
    • Proceedings of the Korean Radioactive Waste Society Conference
    • /
    • 2003.11a
    • /
    • pp.447-452
    • /
    • 2003
  • We had clarified the reactions of the rare earth oxides($RE_2O_3$) with lithium oxide produced in lithium reduction process of oxide fuels. Oxides of scandium, yttrium, praseodymium, neodymium, samarium, europium, gadolinium, ytterbium and lutetium reacted with lithium oxide in the higher concentration than the respective certain critical concentration of lithium oxide and formed complex oxides($LiREO_2$). The critical lithium oxide concentrations for the formation of complex oxides of scandium, yttrium, praseodymium, neodymium, samarium, europium, gadolinium, ytterbium and lutetium oxide were respectively 0.1 wt%, 1.9 wt%, 5.3 wt%, 5.0 wt%, 3.0 wt%, 3.9 wt% 2.9 wt%, 2.6 wt% and 0.3 wt%. Cerium and lanthanum oxide did not react with lithium oxide. These complex oxides obtained from experiments have limited solubility in lithium chloride at $650^{\circ}C$.

  • PDF

I-V Characteristics of Praseodymium-Based ZnO Varistors Doped with Neodymium (네오디뮴이 첨가된 프라세오디뮴계 ZnO 바리스터의 I-V 특성)

  • 박춘현;윤한수;남춘우
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 1999.05a
    • /
    • pp.312-316
    • /
    • 1999
  • I-V characteristics of Praseodymium-based ZnO varistor doped with $Nd_2O_3$ in the range 0.0-2.0mol% sintered at 130$0^{\circ}C$ and 135$0^{\circ}C$ were investigated. In the all sides, ZnO varistors sintered at $1300^{\circ}C$ exhibited much better varistor characteristics than that at 135$0^{\circ}C$. All ZnO varistors doped with $Nd_2O_3$ sintered at $1300^{\circ}C$ exhibited good varistor characteristics but particularly ZnO varistor doped with l.Omol% $Nd_2O_3$ exhibited the best characteristics, which the nonlinear is 65.2 and the leakage current is 4.5pA. It is estimated that ZnO varistor doped with l.Omol% $Nd_2O_3$ will begin to be sufficiently used as basic composition to fabricate a good varistor.

  • PDF

Dielectric properties of Pr$_2$O$_3$ high-k films grown by metalorganic chemical vapor deposition on silicon

  • Nigro, Raffaella-Lo;Vito Raineri;Corrado Bongiomo
    • Electrical & Electronic Materials
    • /
    • v.16 no.9
    • /
    • pp.65.2-65
    • /
    • 2003
  • Praseodymium oxid ($Pr_2$$O_3$) thin films have been deposited on Si(100) substrates by metalorganic chemical vapor deposition using praseodymium tris-2,2,6,6-tetramethyl-3,5-heptandionate as source material. Film structural, morphological, and compositional characterizations have been carried out. Dielectric properties have been studied as well by capacitance-voltage and current-voltage measurements on metal-oxide-semiconductor capacitors of several areas. The $Pr_2$$O_3$ films have shown a dielectric constant = 23-25 and a leakage current density of $8.8{\times}10$-e $A/\textrm{mm}^2$ at +1 V.

  • PDF