The Influence of Stearic Acid Addition on the Superconducting Properties of MgB₂

Increase of the critical current density of MgB2 superconducting bulk samples by means of methylene blue dye additions

“…This is especially important if MgB2 is meant to be used at an operation temperature of 20 K. One strategy for this purpose consists in the addition of nanoparticles acting as flux pinning centers [7][8][9][10][11]. Carbon doping on the boron sites in the MgB2 crystal lattice is also known to be effective in enhancing the pinning force and hence the jc of MgB2 under high magnetic fields [12][13][14][15][16][17][18][19][20]. This is in contrast to the general tendency resulting from foreign element doping on the Mg sites [21][22][23][24][25][26], as well as of Al doping on the B sites [27][28][29][30][31], which induce adverse effects or only limited improvements of the jc(B) performance due to the influence of these elements on various parameters.…”

Critical current density improvements in MgB 2 superconducting bulk samples by K 2 CO 3 additions

“…For several applications involving high magnetic fields such as magnets [1,2], energy storage devices [3,4], high power cables [5], etc., exploiting the superconducting properties of MgB 2 on a large-scale commercial level requires further improvements of the critical current density (j c ) performance of wires and bulk samples, because this parameter tends to be severely suppressed as soon as a magnetic field is acting on the material. This is especially important if MgB 2 is meant to be used at an operation temperature of 20 K. Besides the addition of nanoparticles acting as flux pinning centers [6][7][8], doping on the boron sites in the MgB 2 crystal lattice has been found to be effective in enhancing the pinning force and hence the j c of MgB 2 under high magnetic fields [9][10][11][12][13][14][15][16]. It must however be underscored that only carbon substitution for boron results in improvements, whereas Al, the only other element able to substitute for B to a significant extent, induces adverse effects due to the different influence of these elements on H c2 [17][18][19][20].…”

Artificial pinning centers in MgB2 superconducting bulks

“…Many research groups have worked with chemical doping in an attempt to replace Mg and/or B in the crystalline structure of MgB 2 . Some chemical elements, such as Ti, Zr, Hf, Al, Mn, Li, Si, Ta, Zr and others [3][4][5][6][7][8][9], were used as doping elements. Changes in the intrinsic properties were observed, such as the enhancement of the critical temperature (T c ) and the upper critical magnetic field (H c2 ).…”

“…Changes in the intrinsic properties were observed, such as the enhancement of the critical temperature (T c ) and the upper critical magnetic field (H c2 ). Other effective doping methods occur with addition of carbon sources (including organic sources) [9][10][11][12][13][14][15][16], causing the replacement of B with C atoms in the crystalline structural of MgB 2 [10,11].…”