Preparation of YBa₂Cu₃O_y with Various y by the Heat Treatment in a Vacuum

Abstract

Non-stoichiometric YBa₂Cu₃O_y with the wide composition range (6.15≤y≤6.8) was prepared by the reduction of samples with y??7.0 in a vacuum at around 400°C. The orthorhombic to tetragonal phase transition occurred at y??6.2 at 400°C.