Comparative study of thermal fluctuation induced conductivity in YBa2Cu3O7-d containing Nano-Zn0.95Mn0.05O and Nano-Al2O3 particles

Abstract In this report we presented the fluctuation induced excess conductivity in polycrystalline superconducting samples of YBa2Cu3O7-δ (for brevity YBCO or Y123) with nano-Al2O3 (20 nm) and nano- Zn0.95Mn0.05O (30 nm) particles prepared under the same conditions using the solid-state reaction route. The crystal structure and microstructure were analyzed via X-ray diffraction, scanning and transmission electron microscopies. The crystal structure of Y123 was conserved for samples added with both kinds of nanoparticles. The electrical resistivity dependence with temperature (ρ(T)) was measured and the excess conductivity in the mean field region was analyzed using the Aslamazov and Larkin approach. The fluctuation regions and the critical parameters including the coherence lengths, penetration depth and the effective layer thickness were estimated and compared for both series of samples. The critical physical quantities Bc1(0), Bc2(0) and Jc(0) were computed. Improvements in these critical physical quantities were obtained for samples sintered with 0.02 wt% nanoparticles. The nano-Al2O3 particles are more adequate than nano-Zn0.95Mn0.05O particles for enhancement of flux pinning properties of YBa2Cu3O7-δ.