Study Of Preparing YBCO High Temperature Superconductor On Silver Substrates

Since silver does not react with the YBCO, and fills the pores and empty spaces between the grains, it won lower the Jc of superconductor. It the only metal on which YBCO can be deposited without buffer layers. So it very important to prepare YBCO films on silver substrates.In this thesis, superconducting YBa2Cu3O7..^YBCO films were grown by pulsed laser deposition on Ag( 100), Ag( 111) and Ag( 110) single-crystal surfaces. The electrical and morphological properties of the films have been investigated. It was tested that Ag(1 10) is more suitable for the growth of C-axis oriented YBCO films.Superconducting YBCO films were grown by PLD on biaxially textured Ag(l 10)<21 1> tapes. The influences of temperature, pressure, deposition velocity and laser rates are discussed, and the film with a current density Jc of 1 05A/cm2 was obtained.In order to improve the strength of superconducting tapes, we added Cu in the silver substrates. By using a silver-rich target, the superconducting film with better Jc was obtained. It results from the diffusion of silver into the boundaries of superconducting grains, which degrade the weak-link behavior. Also the silver lowered the melting temperature and makes the YBCO grains growing in C-axis orientaion easier.