Stable {110}⟨112⟩ textured Ag ribbons for biaxially-aligned YBa₂Cu₃O_7-δcoated tapes

Abstract

Texture development in pure Ag was investigated in order to obtain {110}⟨uvw⟩ textured Ag ribbons that can be used as a substrate for YBa2Cu3O7 superconducting coated tapes without any buffer layer. The starting material was 99.95% pure commercial Ag foils. A 20% deformation reduction was used at each step of the cold rolling process after which an optimal annealing was achieved at 800 °C for 4 h in a primary vacuum. This process leads to large-grain ribbons with the {110}⟨112⟩ orientation. A sharp and pure texture is obtained with a FWHM smaller than 6° in the three x-ray pole figures that were used to calculate the orientation distribution function. Crystallographic orientation maps achieved by electron back-scattering diffraction show a misorientation from the normal direction of less than 4°. A twinning mechanism is used to explain the formation of the {110}⟨112⟩ texture. The stability of the {110}⟨112⟩ texture is confirmed by further annealings up to 900 °C, a practical temperature for coated tapes preparation. Lengths up to 25 cm with a uniform {110}⟨112⟩ texture have been obtained.