LOW-TEMPERATURE PROCESSING OF SUPERCONDUCTING TL2BA2CA1CU2OX FILMS ONCEO2 BUFFERED SAPPHIRE

Tl2Ba2Ca1Cu2Ox thin films with excellent alignment have been grown on CeO2 buffered R-plane sapphire using an ex situ anneal step in argon a tmospheres at temperatures of 720-740 degrees C. With this low-tempera ture process we have overcome the serious problem of reaction layers b eing formed at the CeO2/Tl2Ba2Ca1Cu2Ox interface, which can degrade fi lm properties. The presence of a sharp CeO2/Tl2Ba2Ca1Cu2Ox interface h as been confirmed by x-ray diffraction, transmission electron microsco py, and high resolution electron microscopy observations. Films have w ell connected morphologies, with critical temperature (T-c) values of up to 101.6 K and critical current density (J(c)) values of up to 1.25 x 10(5) A cm(-2). (C) 1996 American Institute of Physics.