EXOEMISSION FROM THE SURFACE OF YBA2CU3O7-Y FILMS

Low-temperature electron exoemission from YBa2CU3O7-y superconducting films on MgO, ZrO2(Y2O3), Al2O3, and SrTiO3 single-crystal substrates was studied in the range 77-300 K. Emission-current surges were detect ed at the temperatures of structural transformations in the YBa2CU3O7- y ceramic. According to exoemission data, the films on ZTO(2)O(2)(Y2O3 ) exhibit the highest stability during low-temperature cycling, while the films on Al2O3 exhibit the lowest stability. During low-temperatur e cycling in vacuum, all of the films studied exhibit less pronounced degradation than ceramic materials.