High T_c Superconductor YBa₂Cu₃O_y–Oxygen Content vs T_c Relation–

Abstract

High T c superconductor YBa 2 Cu 3 O y , having various oxygen contents have been examined by a.c. susceptibility, d.c. conductivity and Raman spectrum measurements. The T c is greatly affected by the oxygen content, being lowered by decreasing oxygen content. Particularly, the T c drops markedly when the compound takes a tetragonal form. To confirm the y vs temperature relation, the compound was reexamined by thermogravimetry. The new results cast doubt on our previous y value (6.5> y >5.8).