Characteristics of YBa2Cu3Ox films heat-treated in inert gases

Abstract Influences of gases used for heat treatment upon the crystallization and superconductivity of sputter-deposited YBa 2 Cu 3 O x films were investigated. The heat treatment process consists of three stages; heating up and holding at a certain temperature and then cooling down. On each stage, the air, O 2 , N 2 , Ar, He was flowed and exchanged step by step. The film heated up and held at 800°C in N 2 followed by cooling down in O 2 exhibits the zero-resistivity temperature ( T c ) to be 71 K. Low content of O 2 (less than 1%) in the ambient atmosphere during the stages at high temperature promotes the crystallization of the film, and O 2 is incorporated into the film during the step of cooling down in O 2 resulting in the superconducting phase.