Stability of Tl-Ba-Ca-Cu-O superconducting thin films

We report the stability of TlBa2CaCu2O7 and Tl2Ba2CaCu2O8 on LaAlO3(100) ep itaxial thin films, under a variety of conditions. All films are stable in acetone and methanol and with repeated thermal cycling to cryogenic tempera tures. Moisture, especially vapor, degrades film quality rapidly. These mat erials are stable to high temperatures in either N-2 or O-2 ambients. While total degradation, resulting from Tl depletion, occurs at the same tempera tures for both phases, 600 degrees C in N-2 and 700 degrees C in O-2, the o nset of degradation occurs at somewhat lower temperatures for TlBa2CaCu2O7 than for Tl2Ba2CaCu2O8.