ENVIRONMENTAL REACTIVITY CHARACTERISTICS OF K3C60 AND YBA2CU3O7-X HIGH-TEMPERATURE SUPERCONDUCTOR THIN-FILMS

Recently the environmental reactivity behavior of the copper-oxide sup erconductors has been studied and the following reactivity trends have been established: YBa2Cu3O7 > Ti2Ba2Ca2Cu3O10 > Bi2Sr2CaCu2O8 greater than or equal to La1.85Sr0.15CuO4 > Nd1.85Ce0.15CuO4 > Nd1.85Th0.15Cu O4 In this paper, the degradation characteristics of the most reactive cuprate material, YBa2Cu3O7, are compared with those of the fulleride superconductor, K3C60. Conductivity vs. exposure time measurements ac quired for thin film samples in eight different environments are utili zed to estimate the degradation rates for the two superconductor mater ials. The cuprate superconductor remains relatively stable in the pres ence of dry nitrogen, dry oxygen, vacuum, air and acetonitrile environ ments, but degrades rapidly upon exposure to water solutions. Samples of K3C60 are also unreactive in dry nitrogen and under vacuum, but dec ompose extremely rapidly upon exposure to dry oxygen, air, acetonitril e or water solutions resulting in the complete loss of the superconduc ting properties.