Secondary phase particles in bulk, infiltration-growth processed YBCO investigated by transmission Kikuchi diffraction and TEM

Abstract

We present results of the first application of the transmission Kikuchi diffraction (TKD) technique to bulk, infiltration growth (IG)-processed YBa2Cu3O7−δ (YBCO) superconductors with embedded Y2BaCuO5(Y-211) nanoparticles. By means of focused ion-beam (FIB) milling, TEM slices were prepared from mechanically polished surfaces of bulk, IG-processed YBCO samples. The required optical transparency was reached by additional polishing the resulting surfaces using the FIB and Ar-ion milling. For TKD, the sample was mounted on a homebuilt sample holder in the SEM, which provides the required inclination for TKD. The improved spatial resolution of TKD enabled the investigation of the small Y-211 particles (diameter of about 60–210 nm) embedded in the superconducting YBCO matrix. The fabricated TEM slices further enable the application of transmission electron microscopy to the same sample sections. These tiny Y-211 particles embedded within the YBCO matrix are, together with their strain fields, directly responsible for the high irreversibility fields due to the effective flux pinning of the IG-processed samples.