Very low-frequency anelastic study of YBa₂Cu₃O_7-δin thermal cycling

Abstract

Internal friction (IF) measurement techniques are used to study high-Tc superconducting cuprates. IF peaks associated with oxygen deficiency are located over a temperature range from room temperature to 623 K at frequencies from 10-2 to 5 Hz. IF characteristics, i.e. activation energies, relaxation strength and ordering critical temperature, are investigated in relation to the orthorhombic-to-tetragonal transition, superconducting properties and electrical behaviour with progressively increasing oxygen deficiency, achieved through appropriate thermal cycling. Relationships between these properties are discussed and it is suggested that a fundamental connection exists between the migration of oxygen vacancies and the onset of superconductivity.