Superconducting Properties of Carbonaceous Chemical Doped MgB2

Li, Wenxian; Dou, S. X.

doi:10.5772/10121

Cited by 4 publications

(3 citation statements)

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“…A FTER THE discovery of superconductivity in MgB 2 [1], the Powder in Tube (PIT) technique has been widely used to manufacture MgB 2 -based wires [2] and tapes [3]. The PIT technique can be divided into ex-situ [4]- [6] and in-situ [7]- [9] methods, which differs in the stage at which the reaction take place: for ex-situ tubes are filled with pre-reacted powder, while for in-situ they are filled with precursors of MgB 2 (Mg and B).…”

Section: Introductionmentioning

confidence: 99%

The Influence of Wire Heat Treatment on PIT <inline-formula> <tex-math notation="TeX">$\hbox{MgB}_{2}$</tex-math></inline-formula> Conductors Manufactured Using Laboratory-Made Boron

Bovone

Matera

Bernini

et al. 2015

IEEE Trans. Appl. Supercond.

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In this paper, we discuss the influence of heat treatment (applied to the wire as sintering for ex situ wire, or synthesis for in situ wire) on critical current density of MgB 2 -based wires. A comparison of this influence (changing the synthesis/sintering parameters, i.e., time and temperature, applied to wire samples) for different manufacturing techniques has been given. Boron synthesized in our laboratory by magnesiothermic reduction has been used as precursor. In this paper, we show its behavior with different PIT manufacturing techniques. Different heat treatments of synthesis/sintering have been performed on short wires, to evaluate the suitable one for each manufacturing technique. Ex situ wire shows its best results in terms of J c (10 5 A/cm 2 at 2 T) after heat treatment at 920 • C, while for in situ wires a heat treatment at 800 • C was observed to be the best. A sample prepared following a mixed (ex-situ-in-situ) technique shows an independent J c behavior from the final heat treatment. Here, we report the J c analysis performed from transport and magnetic measurements by using Bean's model for wire samples. The transport J c of the mixed sample shows the best behavior at high magnetic field, one order of magnitude higher than the ex situ wire.

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Section: Introductionmentioning

confidence: 99%

The Influence of Wire Heat Treatment on PIT <inline-formula> <tex-math notation="TeX">$\hbox{MgB}_{2}$</tex-math></inline-formula> Conductors Manufactured Using Laboratory-Made Boron

Bovone

Matera

Bernini

et al. 2015

IEEE Trans. Appl. Supercond.

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“…Specifically, selective doping or selective introduction of disorder in  and  bands are obtained by chemical substitution on the B and Mg site, respectively. The most studied substitution of the former type is Mg(B 1-x C x ) 2 9 , while of the latter type is Mg 1-x Al x B 2 10,11 . On the other hand, neutron irradiation is a very effective and controlled technique to induce disorder in bulk MgB 2 , producing both point defects (vacancies and interstitials) and nanometric size defects, which affect progressively both reversible and irreversible superconducting properties 12 .…”

Section: Introductionmentioning

confidence: 99%

Band filling and disorder effects on the normal state thermoelectric behavior in MgB₂

Pallecchi

Monni²,

Manfrinetti

et al. 2019

J. Phys.: Condens. Matter

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By a combined experimental and theoretical approach, we investigate normal state thermoelectric transport in MgB 2 , as a probe of selective disorder and doping in the  and  bands. We calculate the temperature dependent diffusive Seebeck coefficient S diff (T) with the Boltzmann equation resolved in relaxation time approximation, taking into account the scattering with phonons and impurities, the effect of renormalization and the effect doping in a rigid band approximation. We show that selective disorder has a sizeable effect on the S diff magnitude, as it tunes the relative contributions of  and  bands. Disorder also affects the S diff temperature dependences, eventually yielding a linear S diff (T) behavior in the dirty limit. We also show that band filling has opposite effects on S, depending on which band dominates transport. In parallel, we carry out Seebeck effect measurements on neutron-irradiated Mg 11 B 2 , and on two series of doped samples Mg 1-x Al x B 2 and Mg(B 1-x C x ) 2 . From comparison of calculated S diff (T) and experimental S(T) curves, we demonstrate that diffusive and phonon drag terms give comparable contributions in clean samples, but the phonon drag term is progressively suppressed with increasing disorder. In C and Al doped samples we observe very different experimental behaviors in terms of sign, magnitude and temperature dependence. Indeed, notwithstanding the similar electron doping introduced by both substitutions, C or Al doping yields disorder which mainly affects either  or  bands, respectively. With the help of our ab-initio approach, we are able to disentangle the several effects and prove that Seebeck coefficient is a very sensitive probe of the kind of disorder.

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“…Since the discovery of copper-based superconductors [1], researchers have been very active in this field with the developing of powder in tube (PIT) method [2]. Since the discovery of superconductivity in MgB 2 [3], this technique has been widely used to manufacture MgB 2 wires [4] and tapes [5]. PIT process is divided in ex situ [6,7,8] and in situ [9,10,11], that differs from the stage at which the reaction take place: for ex situ the tube is filled with pre-reacted powder, while for in situ it is filled with precursors of MgB 2 .…”

Section: Introductionmentioning

confidence: 99%

Manufacturing process influence on superconducting properties of MgB₂wires prepared using laboratory made boron

Bovone

Matera

Bernini

et al. 2015

Supercond. Sci. Technol.

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Here we report a systematic study of superconductive properties of mono-filamentary MgB 2 -based wires, manufactured with different filling technique. A detailed comparison of the influence of filling technique and final heat treatment on superconducting properties has been given. Boron used was synthesized in laboratory following magnesiothermic reduction of boron oxide, purified thanks to several acid leaching and heat treated at high temperature, to enhance crystalline degree. Critical current density and critical temperature have been investigated at different synthesis/sintering temperature in order to evaluate their dependence to applied final heat treatment. Critical current density has been evaluated on short wire pieces by magnetic measurement in a MPMS 5.5T Quantum Design SQUID, while critical temperature has been measured with a four probe system, by the drop of resistivity during the cooling of the sample in a liquid helium dewar.

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Superconducting Properties of Carbonaceous Chemical Doped MgB2

Cited by 4 publications

References 75 publications

The Influence of Wire Heat Treatment on PIT <inline-formula> <tex-math notation="TeX">$\hbox{MgB}_{2}$</tex-math></inline-formula> Conductors Manufactured Using Laboratory-Made Boron

The Influence of Wire Heat Treatment on PIT <inline-formula> <tex-math notation="TeX">$\hbox{MgB}_{2}$</tex-math></inline-formula> Conductors Manufactured Using Laboratory-Made Boron

Band filling and disorder effects on the normal state thermoelectric behavior in MgB₂

Manufacturing process influence on superconducting properties of MgB₂wires prepared using laboratory made boron

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Superconducting Properties of Carbonaceous Chemical Doped MgB2

Cited by 4 publications

References 75 publications

The Influence of Wire Heat Treatment on PIT <inline-formula> <tex-math notation="TeX">$\hbox{MgB}_{2}$</tex-math></inline-formula> Conductors Manufactured Using Laboratory-Made Boron

The Influence of Wire Heat Treatment on PIT <inline-formula> <tex-math notation="TeX">$\hbox{MgB}_{2}$</tex-math></inline-formula> Conductors Manufactured Using Laboratory-Made Boron

Band filling and disorder effects on the normal state thermoelectric behavior in MgB2

Manufacturing process influence on superconducting properties of MgB2wires prepared using laboratory made boron

Contact Info

Product

Resources

About

Band filling and disorder effects on the normal state thermoelectric behavior in MgB₂

Manufacturing process influence on superconducting properties of MgB₂wires prepared using laboratory made boron