Enhanced flux pinning in neutron irradiated<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Mg</mml:mi><mml:msub><mml:mi mathvariant="normal">B</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Pallecchi, I.; Tarantini, C.; Aebersold, H. U.; Braccini, V.; Fanciulli, Carlo; Ferdeghini, C.; Gatti, F.; Lehmann, Eberhard; Manfrinetti, P.; Marré, D.; Palenzona, A.; Siri, A. S.; Vignolo, M.; Putti, M.

doi:10.1103/physrevb.71.212507

Cited by 63 publications

(80 citation statements)

References 18 publications

(10 reference statements)

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“…Several superconducting properties of the samples have been reported in Refs. [13,14,15,16,17]. For simplicity and ease of comparison, we label the two samples as in Ref.…”

Section: Experimental Apparatus and Samplesmentioning

confidence: 99%

“…In any cases, the inclusion of defects, besides to change the inter-band scattering, might increase the upper critical field and the critical current, strongly affecting the fluxon dynamics. Very recently, the effects of neutron irradiation have extensively been investigated on polycrystalline Mg 11 B 2 [13,14,15,16,17]. It has been shown that irradiation leads to an improvement in both critical field and critical current density for an exposure level in the range 1 ÷ 2 × 10 18 cm −2 .…”

Section: Introductionmentioning

confidence: 99%

“…[13,14,15,16,17]. We have investigated the unirradiated sample, which clearly shows two-gap superconductivity, and the sample irradiated at the highest neutron fluence, in which the two gaps merge into a single value.…”

Section: Introductionmentioning

confidence: 99%

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Microwave surface resistance of pristine and neutron-irradiated MgB2 samples in magnetic field

et al. 2008

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Abstract. We report on the microwave surface resistance of two polycrystalline Mg 11 B2 samples; one consists of pristine material, the other has been irradiated at very high neutron fluence. It has already been reported that in the strongly irradiated sample the two gaps merge into a single value. The mw surface resistance has been measured in the linear regime as a function of the temperature and the DC magnetic field, at increasing and decreasing fields. The results obtained in the strongly irradiated sample are quite well justified in the framework of a generalized Coffey and Clem model, in which we take into account the field distribution inside the sample due to the critical state. The results obtained in the pristine sample show several anomalies, especially at low temperatures, which cannot be justified in the framework of standard models for the fluxon dynamics. Only at temperatures near Tc and for magnetic fields greater than 0.5Hc2(T ) the experimental data can quantitatively be accounted for by the Coffey and Clem model, provided that the upper-critical-field anisotropy is taken into due account. PACS

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“…Several superconducting properties of the samples have been reported in Refs. [13,14,15,16,17]. For simplicity and ease of comparison, we label the two samples as in Ref.…”

Section: Experimental Apparatus and Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microwave surface resistance of pristine and neutron-irradiated MgB2 samples in magnetic field

et al. 2008

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“…Large engineering applications have been hampered so far by low density and poor flux pinning behaviour of MgB 2 which induces degradation of J c in high magnetic fields. Many researchers have attempted to improve the flux pinning behaviour through several types of processes such as high energy ion-irradiation 11 , chemical doping using different metallic and non-metallic phases and nano particles admixing [12][13][14] . Recent studies have shown that chemical doping may be effective and feasible approach for increasing critical current density of MgB 2 superconductors [15][16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

High critical current density and improved flux pinning in bulk MgB2 synthesized by Ag addition

Shekhar¹,

Giri²,

Tiwari³

et al. 2007

Journal of Applied Physics

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In the present investigation, we report a systematic study of Ag admixing in MgB 2 prepared by solid-state reaction at ambient pressure. All the samples in the present investigation have been subjected to structural/ microstructural characterization employing x-rays diffraction (XRD) and transmission electron microscopic (TEM) techniques. The magnetization measurements were performed by physical property measurement system (PPMS). The TEM investigations reveal the formation of MgAg nanoparticles in Ag admixed samples. These nanoparticles may enhance critical current density due to their size (~ 5-20 nm) compatible with coherence length of MgB 2 (~ 5-6 nm) . In order to study the flux pinning effect of Ag admixing in MgB 2 , the evaluation of intragrain critical current density (J c ) has been carried out through magnetic measurements on the fine powdered version of the as synthesized samples. The optimum result on intragrain J c is obtained for 10 at.% Ag admixed sample at 5K. This corresponds to ~9.23 x 10 7

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“…The inter-grain connectivity (A F ) of the samples varies between 11%-20%. All the additives result in a critical current density (J c ) higher than the stoichiometric MgB 2 sample, where the highest values (e.g., J c (1 T and flux pinning [10][11][12][13][14][15] has been a very active research area. Despite the effort, MgB 2 continues to pose challenges linked with inter-grain connectivity, pinning, and anisotropy.…”

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confidence: 99%

Connectivity and critical current density of in-situ processed MgB2 superconductors: Effect of excess Mg and non-carbon based additives

Bhadauria

Gupta

Kishan

et al. 2014

Journal of Applied Physics

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Articles you may be interested inMicrostructural and crystallographic imperfections of MgB2 superconducting wire and their correlation with the critical current density AIP Advances 4, 017113 (2014) In a sequel to our previous paper (J. Appl. Phys. 113, 036908 (2013)), where we reported comprehensive analysis of inter-grain connectivity (A F ), pinning, percolation threshold (P c ), and anisotropy (c) in a series of ex-situ processed MgB 2 , we address the same issues in in-situ processed samples. MgB 2 samples with stoichiometric composition, excess Mg (5 wt. %) and further 3 wt. % addition of various non-carbon based additives like nano-Ag, nano-Ni, and YBCO are synthesised by the in-situ route. Detailed investigations of X-ray diffraction, magnetization (M), and resistivity (q) as a function of temperature (T) and field (B) in the range 5-300 K and 0-8 T are carried out in all the samples. The resistive superconducting onset T con $ 38.6 6 0.3 K and offset (where q goes to zero) T c0 $ 38.1 6 0.3 K of the samples stay nearly unchanged. The inter-grain connectivity (A F ) of the samples varies between 11%-20%. All the additives result in a critical current density (J c ) higher than the stoichiometric MgB 2 sample, where the highest values (e.g., J c (1 T, 5 K) $ 1.2 Â 10 9 A/m 2 ) are observed for the sample with 5 wt. % excess Mg. The major findings based on quantitative analysis of q (T, B) and J c (B, T) data in all the samples are: (1) along with previously studied ex-situ samples, the J c (A F ) shows a significant increase at A F $ 7%; (2) the irreversibility lines lie lower than the characteristic T c0 (B) lines in the B-T phase diagram; (3) a universal core pinning (dl-and/or dT c -type) mechanism is revealed in the entire T range 5-30 K; and (4) typical values of P c $ 0.57 6 0.04 is indicative of weak link networks. V C 2014 AIP Publishing LLC.

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Enhanced flux pinning in neutron irradiatedMgB2

Cited by 63 publications

References 18 publications

Microwave surface resistance of pristine and neutron-irradiated MgB2 samples in magnetic field

Microwave surface resistance of pristine and neutron-irradiated MgB2 samples in magnetic field

High critical current density and improved flux pinning in bulk MgB2 synthesized by Ag addition

Connectivity and critical current density of in-situ processed MgB2 superconductors: Effect of excess Mg and non-carbon based additives

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