Magnetic characterization of sintered MgB<sub>2</sub>samples: effect of substitution or ‘doping’ with Li, Al and Si

Cimberle, M. R.; Novák, M.; Manfrinetti, P.; Palenzona, A.

doi:10.1088/0953-2048/15/1/308

Cited by 82 publications

(56 citation statements)

References 18 publications

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“…Initially, different substitutions on the Mg site were tested experimentally [21][22][23][24][25][26][27][28][29][30][31][32][33] and theoretically [34][35][36] in an attempt to increase the T c of MgB 2 . Additive elements were also investigated to increase the pinning potential of the material in order to reach higher j c values.…”

Section: Hp-ht Synthesised Substituted (Mg 1-x a X )B 2 Samplesmentioning

confidence: 99%

High-pressure synthesis of pure and doped superconducting MgB₂compounds

Toulemonde¹,

Musolino²,

Flükiger

2003

Supercond. Sci. Technol.

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Superconducting properties of bulk, dense, pure MgB 2 and doped (Mg 1-x A x )B 2 samples with A = Na, Ca, Cu, Ag, Zn and Al were studied for compositional ranges 0 < x ? 0.20. The effect on pinning properties and critical current were investigated, particularly for A = aluminium. The samples were sintered and/or synthesised at high pressure -high temperature in a cubic multi-anvils press (typically : 3.5-6 GPa, 900-1000 °C). They were characterised by x-ray diffraction, scanning electron microscopy and their superconducting properties were investigated by a.c. susceptibility, magnetisation (VSM and SQUID) and transport measurements under magnetic field. Only Al substitutes really on the Mg site. The other elements form secondary phases with B or Mg which do not act as pinning centres. No positive effect is observed on the superconducting properties of the bulk MgB 2 samples added with these doping elements : T c , j c critical current, H irr and H c2 . For Al, the effect on H c2 remains small, and the irreversibility line does not move, thus not improving the critical current of the Al-doped MgB 2 samples.

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Section: Hp-ht Synthesised Substituted (Mg 1-x a X )B 2 Samplesmentioning

confidence: 99%

High-pressure synthesis of pure and doped superconducting MgB₂compounds

Toulemonde¹,

Musolino²,

Flükiger

2003

Supercond. Sci. Technol.

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“…There have been several theoretical predictions of an increase in T c by chemical substitutions at the Mg and B sublattice 6,7 . There have been experimental reports of substituting Mg by Al 8,9 , Li 10,11 , Si 10 , 3d transition metals 12,13,14 and recently 4d transition metals 15 . Almost all substitutions have led to a decrease in T c , with an exception of Zn 14 , which shows no change even for 30% substitution.…”

Section: Introductionmentioning

confidence: 99%

Carbon solubility and superconductivity in MgB2

Bharathi

Balaselvi

Kalavathi

et al. 2002

Physica C: Superconductivity

119

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Successful replacement of B by C in the series MgB 2-x C x for values of x upto 0.3 are reported. Resistivity and ac susceptibility measurements have been carried out in the samples. Solubility of carbon, inferred from the observed change in the lattice parameter with carbon content indicates that carbon substitutes upto x=0.30 into the MgB 2 lattice. The superconducting transition temperature, T C measured both by zero resistivity and the onset of the diamagnetic signal shows a systematic decrease with increase in carbon content upto x=0.30, beyond which the volume fraction decreases drastically. The temperature dependence of resistivity in the normal state fits to the Bloch-Gruneisen formula for all the carbon compositions studied. The Debye temperatures, θ D , extracted from the fit is seen to decrease with carbon content from 900K to 525K, whereas the electron-phonon interaction parameter, λ, obtained from the McMillan equation using the measured T C and θ D , is seen to increase monotonically from 0.8 in MgB 2 to 0.9 in the x=0.50 sample. The ratio of the resistivities between 300K and 40K versus T C is seen to follow the Testardi correlation for the C substituted samples. The decrease in T C is argued to mainly arise due to large decrease in θ D with C concentration and a decrease in the hole density of states at N(E F ).

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“…In particular, proton irradiation [14] increased B irr at 20 K, but also suppressed low-field J c , whereas alloying seems to enhance J c , but has little effect on B irr [12,13]. Better results were recently obtained by adding nanoparticles to MgB 2 [19,20,21].…”

Section: Introductionmentioning

confidence: 99%

Correlated vortex pinning in Si-nanoparticle doped MgB2

Kušević

Babić

Husnjak

et al. 2004

Solid State Communications

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The magnetoresistivity and critical current density of well characterized Si-nanoparticle doped and undoped Cu-sheathed MgB2 tapes have been measured at temperatures T ≥ 28 K in magnetic fields B ≤ 0.9 T. The irreversibility line Birr(T ) for doped tape shows a stepwise variation with a kink around 0.3 T. Such Birr(T ) variation is typical for high-temperature superconductors with columnar defects (a kink occurs near the matching field B φ ) and is very different from a smooth Birr(T ) variation in undoped MgB2 samples. The microstructure studies of nanoparticle doped MgB2 samples show uniformly dispersed nanoprecipitates, which probably act as a correlated disorder. The observed difference between the field variations of the critical current density and pinning force density of the doped and undoped tape supports the above findings.

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Magnetic characterization of sintered MgB₂samples: effect of substitution or ‘doping’ with Li, Al and Si

Cited by 82 publications

References 18 publications

High-pressure synthesis of pure and doped superconducting MgB₂compounds

High-pressure synthesis of pure and doped superconducting MgB₂compounds

Carbon solubility and superconductivity in MgB2

Correlated vortex pinning in Si-nanoparticle doped MgB2

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Magnetic characterization of sintered MgB2samples: effect of substitution or ‘doping’ with Li, Al and Si

Cited by 82 publications

References 18 publications

High-pressure synthesis of pure and doped superconducting MgB2compounds

High-pressure synthesis of pure and doped superconducting MgB2compounds

Carbon solubility and superconductivity in MgB2

Correlated vortex pinning in Si-nanoparticle doped MgB2

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Product

Resources

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Magnetic characterization of sintered MgB₂samples: effect of substitution or ‘doping’ with Li, Al and Si

High-pressure synthesis of pure and doped superconducting MgB₂compounds

High-pressure synthesis of pure and doped superconducting MgB₂compounds