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  • 1
    Electronic Resource
    Electronic Resource
    Flux pinning in melt-processed ternary (Nd–Eu–Gd)Ba2Cu3Oy superconductors with Gd2BaCuO5 addition (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5705-5711 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The flux pinning behavior of ternary melt-processed (Nd–Eu–Gd)Ba2Cu3Oy superconductors is studied with varying Gd2BaCuO5 second-phase (Gd-211) defect concentrations using magnetotransport and magnetization measurements. The critical current density, Jc increases with the addition of Gd-211 particles displaying a maximum value of Jc for 30% at zero and in intermediate field range and decreases on further addition of Gd-211 particles. A pronounced field-induced bump feature in the resistivity was observed. The dynamic scaling of the resistance suggests the low temperature phase as the vortex-glass phase. The current–voltage characteristics over the whole transition temperature regime show a linear flux–flow type behavior that favors the phenomenon of vortex entanglement in the liquid phase. The Nd/Ba substitution sites along with Gd-211 second-phase particles refined by the addition of a small amount of Pt are one of the possible reasons for the vortex entanglement in the liquid phase. The in-plane and out-of-plane resistance measurements clearly show the correlation of the vortices in the liquid state favoring some influence of twin planes and occasionally occurring natural grain boundaries on the liquid state as well. These defects give rise to high critical current density at low temperature with significant enhancement in pinning favoring the glassy phase to occur. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371582
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  • 2
    Electronic Resource
    Electronic Resource
    Evidence of strong flux pinning in melt-processed ternary (Nd–Eu–Gd)Ba2Cu3Oy superconductors (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 253-255 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The flux pinning behavior of ternary melt-processed (Nd–Eu–Gd)Ba2Cu3Oy superconductors is studied with varying defect concentrations using magnetotransport and magnetization measurements. A huge field-induced bump feature in the resistivity with increasing defect density, field-induced magnetization kink and linear voltage-current (V-I) characteristics over the whole transition temperature regime favor the phenomenon of vortex entanglement in the liquid phase. The Nd/Ba substitution sites along with the fine second-phase particles are one of the possible reasons for the vortex entanglement and these defects give rise to high critical current density and reduced dissipation at low temperature with significant enhancement in pinning. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124339
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  • 3
    Electronic Resource
    Electronic Resource
    Flux pinning in ternary (Nd0.33Eu0.33Gd0.33)Ba2Cu3Oy melt-processed superconductors (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2351-2353 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The flux pinning characteristics of ternary melt-processed (Nd0.33Eu0.33Gd0.33)Ba2Cu3Oy (NEG) superconductors are studied in the temperature range 60≤T≤90 K. NEG samples exhibit a strongly developed peak effect in the dependence of the critical current densities on the external field, Ha. The scaling of the pinning forces versus the reduced field h=Ha/Hirr (where Hirr denotes the irreversibility field) yields a peak at h0=0.5 which is an indication of pinning provided by a spatial variation of the transition temperature. The presence of a weaker superconducting second phase is demonstrated by means of field cooling and warming experiments in fields up to 7 T. Furthermore, we discuss the possible effect of the magnetic moments of Gd and Nd on the flux pinning. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122458
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  • 4
    Electronic Resource
    Electronic Resource
    Flux pinning in ternary (Nd–Eu–Gd)Ba2Cu3O7−δ: Optimization for the highest pinning (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2033-2035 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optimization of high-quality melt-processed ternary (Nd–Eu–Gd)Ba2Cu3O7−δ composite samples has been carried out to achieve the largest pinning. Our results suggest that the interaction between the twin planes and the fine second-phase precipitate forms a strongly pinned entangled vortex liquid in which vortices are correlated along the c axis. This pinned vortex liquid freezes into a glassy state at low temperature rendering high critical current density, Jc. The maximum Jc can be achieved in as-grown optimally annealed twinned sample with second phase precipitate without disturbing the twin influence. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1312863
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  • 5
    Electronic Resource
    Electronic Resource
    Strong pinning in ternary (Nd–Sm–Gd)Ba2Cu3Oy superconductors (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1016-1018 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the flux pinning in melt-textured (Nd0.33Sm0.33Gd0.33)Ba2Cu3Oy NSG-123 superconductors with various numbers of Gd2BaCuO5 (Gd-211) particles. Transmission electron microscopy (TEM) showed that submicron Gd-211 particles are uniformly distributed in the superconductive matrix. Dark-field TEM observations further showed that a high density of RE rich RE1+xBa2−xCu3Oy (RE-123ss) clusters 3–10 nm in size were distributed in the NSG-123 matrix. A strongly developed fishtail was observed in the magnetization hysteresis loops of all the samples. A critical current density of 100 kA/cm2 (77 K) was achieved at the secondary peak field of 2 T for the H(parallel) c axis in the NSG-123 sample with 10 mol % Gd-211. Large grain NSG-123 pellets with 30 mol % Gd-211 and 20 wt % AgO2, 30 mm in diameter and 15 mm in height, exhibited a single-cone profile with a peak value of 1.2 T at 77 K. A higher trapped-field value of 1.5 T was recorded at 2 T, reflecting the secondary peak effect. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1447582
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  • 6
    Electronic Resource
    Electronic Resource
    Enhancement of Jc by 211 particles in ternary (Nd0.33Eu0.33Gd0.33)Ba2Cu3Oy melt-processed superconductors (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 91-93 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: (Nd0.33Eu0.33Gd0.33)2BaCuO5 (NEG-211) particles are added to ternary (Nd0.33Eu0.33Gd0.33)Ba2Cu3Oy (NEG) bulk, melt-processed superconductors. By means of transmission electron and polarized light microscopy, we found that two types of 211 particles are formed; large NEG-211 and submicron-sized particles containing mostly Gd in the rare earth site are formed which can act as effective flux pinning sites. The critical current density at zero field increases monotonously as a function of the NEG-211 concentration, but the secondary peak vanishes above 40 mol % 211 addition. As a result, a critical current density of 68 000 A cm−2 at 77 K and 2.5 T applied field is achieved with at 40 mol % 211 additions. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125666
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  • 7
    Electronic Resource
    Electronic Resource
    Optimization of matrix chemical ratio for high flux pinning in ternary (Nd–Eu–Gd)Ba2Cu3Oy (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3107-3109 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We prepared (Nd, Eu, Gd)Ba2Cu3Oy samples with various Nd: Eu: Gd ratios in the rare earth site. It was found that the three elements contributed to flux pinning in different ways. Nd mainly enhanced flux pinning at low magnetic fields, Eu controlled the second peak position and the irreversibility field, while Gd slightly enhanced intermediate and high-field Jc values. Scaling analyses for the pinning force density as a function of the reduced field h=Ha/Hirr (where Hirr denote the irreversibility field) showed that the highest peak was achieved at h=0.56. This value is even higher than the theoretically predicted highest value of h=0.5. We also show that a maximum flux pinning can be achieved in the whole magnetic field when very fine secondary phase particles are dispersed in a superconducting (Nd, Eu, Gd)Ba2Cu3Oy matrix with an optimum Nd: Eu: Gd ratio. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1414303
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  • 8
    Electronic Resource
    Electronic Resource
    Enhanced room-temperature magnetoresistance in partially melted La0.67Ca0.33MnO3 manganites (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 763-765 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed magnetic and transport measurements on La0.67Ca0.33MnO3 polycrystalline and partially melted samples. The magnetization and resistance decrease as sintering temperature is increased. The insulator-to-metal transition temperature is remarkably enhanced in the partially melted sample, enabling its possible applications at room temperature. The microscopic studies in melt samples show an excellent connectivity between grains, suggesting the enhancement of percolative transport by opening new conduction channels and the disappearance of magnetic phase boundary at elevated temperature by the ordering of Mn spins blocked at the grain boundary of sintered samples. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125887
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  • 9
    Electronic Resource
    Electronic Resource
    Control of neuronal pathway selection by a Drosophila receptor protein-tyrosine kinase family member (1995)
    [s.l.] : Nature Publishing Group
    Nature 376 (1995), S. 171-174 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] DURING development, neurons are capable of selecting specific pathways that lead them to their appropriate target areas. A variety of molecular mechanisms are thought to be involved in pathway recognition, including cell adhesion1, repulsion2,3and ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/376171a0
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  • 10
    Electronic Resource
    Electronic Resource
    D.C susceptibility studies on silver doped BPSCCO (2223) superconductors
    Amsterdam : Elsevier
    Physica C: Superconductivity and its applications 235-240 (1994), S. 3199-3200 
    Details
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0921-4534(94)91126-6
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