Enhanced superconducting transition temperature through a small amount of Nd substitution for Ba in NdBa₂Cu₃Oy

Abstract Single-phase samples of polycrystalline Nd 1+ x Ba 2− x Cu 3 O y with a narrow range of x ≤ 0.05 have been successfully synthesized by sintering under a reduced oxygen atmosphere. The oxygen content increases with increasing x to maintain charge neutrality, while the hole concentration in the CuO 2 plane remains nearly constant. The superconducting transition temperature ( T c ) increases from 95.0 K at x = 0 to 96.6 K at x = 0.05. It has been widely believed that the substitution of Nd for Ba suppresses superconductivity. However, this study has shown that a small amount of Nd substitution for Ba enhances T c .