Bulk MgB2 with added SiO2 nanoparticles was synthesized by using a simple solid-state reaction route. The lattice constant in the c-direction increased with additive content due to a small amount of Si being doped into the lattice of the MgB2. However, TC was almost fixed at 37.2K. The addition of SiO2 nanoparticles also improved the JC–H and Hirr–T characteristics of MgB2 when the doping content was lower than 7%. At 20K and 1T, JC for the sample with 7% doping attained 2.5 x 105A/cm2. Microstructural analysis revealed that a high density of MgSi2 nanoparticles (10–50nm) existed inside the MgB2 grains; leading to the formation of a nanocomposite superconductor.

Improved Flux Pinning Behaviour in Bulk MgB2 Achieved by Nano-SiO2 Addition. X.F.Rui, Y.Zhao, Y.Y.Xu, L.Zhang, X.F.Sun, Y.Z.Wang, H.Zhang: Superconductor Science and Technology, 2004, 17, 689-91