A series of polycrystalline MgB2 samples were prepared with different amounts of nanosized CeO2 inclusions. Samples were subjected to x-ray diffraction, scanning electron microscopy, and atomic force microscopy characterization. We found that nano- CeO2 inclusions affect the lattice parameters as well as the microstructure of MgB2 superconductor. An increase in the lattice parameters a and c was observed due to nanoinclusions up to 2 wt %. The morphology of the surface of pure samples reveals a considerable number of weak-links, randomly oriented grains and clean grain boundaries. While in samples with nanoinclusions, grain surfaces and boundaries were decorated with nanosized CeO2 particles and low traces of secondary phases. A reduction in the average grain size and roughness was also observed for samples with highest inclusions. The superconducting properties have been measured using the magnetization measurement M (H) in magnetic field up to 5 T. Significant enhancement of the superconducting critical current density Jc and the pinning force Fp in applied magnetic field was observed due to nano- CeO2 addition. However, no considerable change in the transition temperature Tc and transition width was observed. These results were interpreted in terms of the scaling of the flux pinning in granular superconducting networks which leads to a better basic understanding of the performance of MgB2 system in relatively high applied magnetic fields.
ASJC Scopus subject areas
- Physics and Astronomy(all)