Buffer layer/film interactions in the growth of Tl_2Ba_2Ca_1Cu_2O_x films on CeO_2 buffered sapphire

摘要

Tl_2Ba_2Ca_1Cu_2O_x thin films have been grown on highly textured CeO_2 layers deposited onto R -plane sapphire substrates. The Tl_2Ba_2Ca_1Cu_2O_x films have critical temperature (T_c) values around 95 K and current density (J_c) values up to 8 x 10~4 A/cm~2. The films are c-axis oriented even though we have identified the formation of a polycrystalline BaCe(Tl)O_3 layer by reaction between the buffer layer and the superconducting precursor during the thalliation process.