Intergrain Connectivity and Resistive Broadening in Vortex State: A Comparison Between ${\rm MgB}_{2}$, ${\rm NbSe}_{2}$ and ${\rm Bi}_{2}{\rm Sr}_{2}{\rm Ca}_{2}{\rm Cu}_{3}{\rm O}_{10}$ Superconductors

Kaushik, S. D.; Patnaik, S.

doi:10.1109/tasc.2007.899387

Cited by 3 publications

(4 citation statements)

References 16 publications

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“…This curvature may arise from the difference in magnitude of B c2 (0) between the single-crystal sample used for pulsed-field measurements and our tape, optimized for high J c , or our assumption that κ is independent of temperature. A concave curvature of B c2 (T) has been observed in several BiSCCO systems [35][36][37] which can be characterized using a scaling function 1 , where fitting parameters from the J c data for our BiSCCO sample are B c2 (0) = 84.5 T and T c = 110.8 K. The data in figure 2 show that there is reasonably good agreement between the reduced temperature dependence and the free parameters obtained from different measurements on different samples. For BiSCCO, the current densities are a significantly smaller fraction of the depairing current density than, for example, in YBCO.…”

Section: Experimental Functional Form Of J Csupporting

confidence: 54%

“…In figure 2, we have compared these functional forms with B c2 values from the literature, as well as with those obtained from in-house ac magnetic 8 K] respectively. The data from the literature are from Godeke [33], Sekitani [34], Osofsky [35], Zavaritsky [36] and Kaushik [37]. susceptibility measurements.…”

Section: Experimental Functional Form Of J Cmentioning

confidence: 99%

“…The lines describe the reduced temperature relations for B c2 (T) given in (a)-(c) that were obtained from fits to the J c data, where B c2 (0)[T c ] are 26.3 T [16.2 K], 68.5 T [87.6 K] and 84.5 T [110.8 K] respectively. The data from the literature are from Godeke[33], Sekitani[34], Osofsky[35], Zavaritsky[36] and Kaushik[37].…”

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confidence: 99%

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The critical current density of grain boundary channels in polycrystalline HTS and LTS superconductors in magnetic fields

Sunwong¹,

Higgins²,

Tsui³

et al. 2013

Supercond. Sci. Technol.

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We provide evidence that a single mechanism-flux flow along channels-can explain the functional form of the critical current density (J c) in the low temperature superconductor Nb 3 Sn and in the high temperature superconductors (HTS) YBa 2 Cu 3 O 7-δ (YBCO) and (Bi,Pb) 2 Sr 2 Ca n-1 Cu n O x (BiSCCO) in low and high magnetic fields. In this paper, we show that standard flux pinning theories, used for the last four decades to describe J c in low temperature superconductors (LTS), cannot explain the strain dependence of J c in YBCO because J c is a function of strain but the average superconducting properties are not. We conclude that in the polycrystalline samples presented here, the channels are grain boundaries that are narrow and metallic in Nb 3 Sn and YBCO but wide and semiconducting in BiSCCO. Strain alters J c by changing the superconducting properties of the grains in Nb 3 Sn but by changing the grain boundaries in YBCO.

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Section: Experimental Functional Form Of J Csupporting

confidence: 54%

Section: Experimental Functional Form Of J Cmentioning

confidence: 99%

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The critical current density of grain boundary channels in polycrystalline HTS and LTS superconductors in magnetic fields

Sunwong¹,

Higgins²,

Tsui³

et al. 2013

Supercond. Sci. Technol.

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“…Their results indicate that the low packing factor and poor connectivity strongly restrict J C in MgB 2 . Many experimental methods, such as Campbell's method, 10 magneto-optical and electromagnetic studies, 11 magnetoresistance and radio frequency penetration depth techniques 12 have been used to investigate the intergrain connectivity of MgB 2 .…”

Section: Introductionmentioning

confidence: 99%

Intergrain connectivity of MgB2 ceramics studied by impedance analysis

Wang¹,

Wang²,

Zeng³

et al. 2010

Journal of Applied Physics

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First, by using of the conventional Rowell analysis, we demonstrated that the addition of nano BN particles can effectively eliminate MgO and pores in MgB 2 resulting in a very high density and good connectivity of BN-doped MgB2. Then, another method-low-frequency dielectric impedance analysis-was introduced to characterize the properties of the grain boundaries of MgB 2 . A comparative impedance study was performed in the frequency range from 100 Hz to 100 MHz on pure and nano BN-doped MgB 2 . The study revealed some following interesting results: (1) a dielectric resonance around frequency of 10 8 in both samples was observed, which was argued to be related to an inductance-capacitance and (2) the pure sample has two dielectric relaxations originating from intergrains, while the doped sample has only one intergranular contribution. This convinces that the electric connectivity of the doped sample is really improved by the addition of nano BN particles. Our results indicate that dielectric technique may be a useful tool to characterize the grain boundary properties and grain boundary-related properties of MgB 2 . KeywordsIntergrain, connectivity, MgB2, ceramics, studied, impedance, analysis First, by using of the conventional Rowell analysis, we demonstrated that the addition of nano BN particles can effectively eliminate MgO and pores in MgB 2 resulting in a very high density and good connectivity of BN-doped MgB 2 . Then, another method-low-frequency dielectric impedance analysis-was introduced to characterize the properties of the grain boundaries of MgB 2 . A comparative impedance study was performed in the frequency range from 100 Hz to 100 MHz on pure and nano BN-doped MgB 2 . The study revealed some following interesting results: ͑1͒ a dielectric resonance around frequency of 10 8 in both samples was observed, which was argued to be related to an inductance-capacitance and ͑2͒ the pure sample has two dielectric relaxations originating from intergrains, while the doped sample has only one intergranular contribution. This convinces that the electric connectivity of the doped sample is really improved by the addition of nano BN particles. Our results indicate that dielectric technique may be a useful tool to characterize the grain boundary properties and grain boundary-related properties of MgB 2 .

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