Electronic Structures and Superconducting Mechanism of Ba₂Y₁Cu₃O₇

Abstract

The high- T c superconductor Ba 2 Y 1 Cu 3 O 7 with the oxygen-deficient perovskite structure was prepared almost in a single-phase with T co of 125 K, T c of 95 and T ce of 93 K. The XPS valence-band spectrum showed a relative large N ( E F ), density of states at the Fermi level. The XPS Cu 2p 3/2 peak is divided into three peaks which are attributed to monovalent, bivalent and trivalent Cu ions with the concentration ratio of 1:2:1. These results and the peculiar lattice structure lead to the T c enhancement mechanism from the plasmon or exciton origin due to the Cu d-hole creation and annihilation resonating with vibration modes of the CuO 5 and CuO 4 clusters. The T c value was calculated.