Twin spacing and its correlation with critical current density in melt-textured YBCO with yttria nanoparticle addition

Twin boundaries have been proved to be effective flux pinning centers in YBa₂Cu₃O_7-x (YBCO). Increases in twin density yield higher values of critical current density. Twin spacings in melt-textured grown (MTG) YBCO with different amounts of yttria nanoparticles were investigated with a new x-ray method. Twin spacings from the x-ray method were compared with those from transmission electron microscopy to show applicability. From investigation, MTG-YBCO with 11.9 weight percent yttria and oxygenation temperature at 680°C showed a colony size of 3.65 microns. This particular sample had a small twin spacing of 33 nm with a corresponding high value of critical current density (J_c) of 1.2 × 10⁴ A/cm².