Nanoscale characterization of the doped SrZrO3 nanoparticles distribution and its influence on the microstructure of Bi2Sr2CaCu2O8+δ film

Abstract

Due to the doping of SrZrO3 nanoparticles, the performance improvement of Bi2Sr2CaCu2O8+δ (Bi-2212) high-temperature ceramic superconducting films is significant. To comprehensively explore the reasons for the performance enhancement, in this study, the distribution of doped SrZrO3 nanoparticles and its influence on the Bi-2212 matrix microstructure were characterized at the nanoscale. A small amount of interfacial SrZrO3 nanoparticles have a semi-coherent heterointerface with the SrTiO3 substrate accompanied by a non-ideal arrangement of misfit dislocations. In some cases, the interfacial SrZrO3 lattice has a tilt of ∼3.5° off the heterointerface. For the SrZrO3 nanoparticles embedded in the film, due to the different interplanar spacing between the Bi-2212 and the SrZrO3 lattice, a large number of intergrowths were generated which triggered the subsequent yield of a high density of stacking faults and lattice distortions in the Bi-2212 matrix. Moreover, due to thermal expansion mismatch, the maximum shear stress between the SrZrO3/Bi-2212 heterointerface reached to 0.685 GPa. The intergrowth, stacking fault, lattice distortion, and shear stress are believed to be primary magnetic flux pinning centers that cause the improved performance of Bi-2212(SrZrO3) nanocomposite films.