Magnetic instability in irradiated MgB2 dense samples

Abstract

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Doping effect of nano-SiC on structural and superconducting properties of MgB2 bulks prepared by PIST method in air

“…At 5 K, J C jumps abruptly at lower fields where the estimation of J C may not be accurate due to the flux jump. Materials with high critical current density, high magnetic diffusivity and low heat capacity usually cause thermomagnetic flux jumps in magnetization hysteresis loop [20,21]. J C (H) behavior of all doped samples is significantly enhanced with respect to the pure sample and it is the best for samples MS4 and MS5 at higher fields.…”

Burned Rice Husk: An Effective Additive for Enhancing the Electromagnetic Properties of MgB2 Superconductor

“…A detailed experimental and theoretical study of flux jumps in magnetization curves of a highly dense polycrystalline MgB 2 superconductor was recently provided by Romero‐Salazar and colleagues 27,5 The BRH‐doped MgB 2 samples show a drastic enhancement of J C compared with pure MgB 2 . Of all the doped samples, the 5 wt% BRH‐doped sample gives the best performance and the level of J C enhancement in high magnetic fields is very similar to that of the J C increase exhibited by nano‐SiC doping 5–9 . For the undoped sample, J C drops rapidly in the presence of the magnetic field but for doped samples, the J C values at higher fields increase by more than an order of magnitude.…”

“…Therefore, the improvement of J C under magnetic field is essential for the development of MgB 2 for magnetic applications. Different approaches such as chemical doping and irradiation have been used to introduce flux‐pinning centers in MgB 2 matrix to enhance the pinning strength 4–9 …”

“…Different approaches such as chemical doping and irradiation have been used to introduce flux-pinning centers in MgB 2 matrix to enhance the pinning strength. [4][5][6][7][8][9] Of the various elements and compounds being doped in MgB 2 , carbon-containing nanosized compounds such as SiC, C, and B 4 C have been found to be the most effective dopants for significant J C enhancement in high magnetic fields. [6][7][8][9][10][11][12][13][14][15][16][17] This is mainly due to the substitution of carbon for boron, which has a great impact on the carrier density and impurity scattering because MgB 2 is a two-gap superconductor.…”

Estudo das propriedades supercondutoras e da microestrutura do supercondutor Mg'B IND. 2' puro e dopado com compostos de carbono

“…Na literatura comenta-se que esse tipo de fenômeno costuma ocorrer para medidas abaixo de 10K (YANMAZ et al, 2009) Comparando os gráficos das Figuras 5.28 a 5.31, nota-se que a amostra MgB 2 +SIL, é a que apresenta menos "flux jump", em contraste a MgB 2 +SiC é a que apresenta mais "flux jump". Segundo Durán et al (2008), a presença de saltos pode estar relacionada à dissipação térmica, movimento das linhas de fluxo e a alta quantidade de defeitos, causando instabilidades térmica e magnética.…”