ELECTRICAL AND STRUCTURAL-PROPERTIES OF YBA2CU3O7 FILMS ON POLY AND SINGLE CRYSTALLINE OXIDES OF CU AND NI

YBa2Cu3O7 films were deposited by inverted cylindrical magnetron sputtering on metallic substrates as e.g. Ni sheet covered with the natural oxide as barrier layer. These films grow c-axis oriented with a T(c),R = 0 of about 80 K. For a better understanding of the growth procedure on metal oxides, thin YBa2Cu3O7 films were prepared on single crystalline NiO with the orientations (100), (110) and (111). These are also c-axis oriented and exhibit T(c),R = 0 = 86 K. So far (100) oriented NiO yields the best results, as can be seen from the rocking curve with FWHM = 0.4-degrees, from channeling measurements and from the critical current density J(c),77K,B = 0 = 10(5) A/cm2. Even in a magnetic field of 12 T with B parallel-to c-axis the critical current density at 50 K exceeds 10(5) A/cm2. On other substrate orientations J(c) is much smaller. Similar investigations were performed on the Cu/Cu2O/YBa2Cu3O7-system. Films on polycrystalline Cu2O exhibit metallic R(T) behavior with T(c),R = 0 almost-equal-to 80 K. First results on single crystalline Cu2O substrates are quite promising.