Remarkable properties of Tl-Ba-Ca-Cu-O thin films following post-growth high-temperature annealing

Tl-2212 and Tl-1212 are the two easiest unsubstituted Tl-Ba-Ca-Cu-O superconducting thin films to grow. Both phases exhibit T/sub c//spl ges/95 K, J/sub c/(5 K)>10 MA/cm/sup 2/ and smooth morphologies. We report on the properties of both materials following one hour furnace anneals in dry ambients of pure oxygen or nitrogen at temperatures ranging from 50-700/spl deg/C. The stability of these films to high temperatures in each ambient is important for device processing. Of equal interest is the controlled partial volatilization of Tl-oxide at modest temperatures from nano-site regions within Tl-1212 films. We correlate such modifications with increases in flux pinning strength in Tl-1212 films. Tl-2212 films maintain their superconducting properties to even higher temperatures than Tl-1212 films. Optimum annealing appears to also increase flux pinning, although not to the same degree as for Tl-1212 films.