Effect of PVA doping on flux pinning in bulk MgB 2
Abstract
The synthesis and characterization of PVA (Poly Vinyl Acetate) doped bulk MgB 2 superconductor is reported here. PVA is used as a carbon source. PVA doping effects made two distinguishable contributions: first enhancement of Jc field performance and second an increase in Hc2 value, both because of carbon incorporation into MgB 2 crystal lattice. The susceptibility measurement reveals that Tc decreased from 37 to 36 K. Lattice parameter ‘ a’ decreased from 3.085 Å to 3.081 Å due to the partial substitution of carbon at boron site. PVA doped sample exhibited the Jc values greater than 10 5 A/cm 2 at 5 and 10 K at low fields; which is almost 3 times higher than the pure one, while at high fields the Jc is increased by an order of magnitude in comparison to pure MgB 2. From ρ( T) H measurements we found higher Tc values under magnetic field for doped sample; indicating an increase in Hc2. Also the magnetization measurements exhibited a significant enhancement in Hirr value. The improved performance of PVA doped MgB 2 can be attributed to the substitution of carbon at boron site in parent MgB 2 and the resulting impact on the carrier density and impurity scattering. The improved flux pinning behavior could easily be seen from reduced flux pinning force plots.
- Publication:
-
Physica C Superconductivity
- Pub Date:
- November 2007
- DOI:
- 10.1016/j.physc.2007.05.046
- arXiv:
- arXiv:0708.3885
- Bibcode:
- 2007PhyC..466...46V
- Keywords:
-
- Condensed Matter - Superconductivity;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- 14 Pages of Text + Figs. To appear in Physica C