Effects of Metal (Ag, Sn and Zn) Nanoparticles Inserted into MgB₂ Grain Boundaries on Transport and Superconducting Properties

Abstract

MgB 2 grains were coated with metal nanoparticles (Ag, Zn and Sn) using the barrel sputtering technique, and transport and superconducting properties were evaluated. Almost all MgB 2 grains were uniformly coated with metal nanoparticles with average diameters of less than 20 nm. The electrical resistivity of the coated MgB 2 decreased as the amount of metal coating increased. The critical current densities of almost all coated MgB 2 were enhanced compared to those of bare MgB 2 . These results explained the improvement of intergranular connectivity between MgB 2 grains by the insertion of metal nanoparticle in grain boundaries. After annealing at 473 K, only MgB 2 coated with Sn nanoparticles showed a decrease in electrical resistivity and the enhancement of the critical current density. These results can be understood by the effect of improvement of intergranular connectivity between MgB 2 grains by annealing.

Zinc Nanoparticles at Intercrystallite Sites of (Cu0.5Tl0.5)Ba2Ca3Cu4O12−δSuperconductor

“…The suppression of superconducting properties was observed after addition of core shell Ni/NiO nanoparticles and ZnFe 2 O 4 nanoparticles in CuTl-1223 matrix, which was attributed to scattering/pair-breaking of carriers across these magnetic nanoparticles due to spin-interaction [7,8]. Metallic nanoparticles (i.e., Ag, Zn, and Sn) in MgB 2 superconducting matrix have enhanced , which was attributed to increased intergrains connectivity [9]. Mechanical and electrical properties of (Cu 0.5 Tl 0.5 )-1223 superconducting 2 Journal of Nanomaterials phase added with Fe 2 O 3 nanoparticles were studied and increase in was observed with low concentration of these nanoparticles (up to = 0.2 wt.%) followed by systematic decrease with > 0.2 wt.% [10].…”

Flux Pinning in Y- and Ag-Doped MgB<sub>2</sub>

“…If, on the contrary, substitution of Magnesium with Copper occurs, a hole-donor compound is obtained, which produced an unexpected reduction in c T [20] [21]. Also Silver doping in MgB 2 yielded an increase of the critical current, due to the formation of MgAg nanoparticles that acted as pinning centres [22]- [24].…”