The Microstructure of High—Critical Current Superconducting Films

High TC Superconducting Films from Metallo-Organic Precursors

High Tc superconducting films of heavy metal soaps (derived from carboxylic acid precursors) have been prepared on Si and other substrates. The precursors were synthesized and mixed in appropriate molar ratios to form the high Tc compound YBa2Cu3O7−x, using a high boiling point common solvent base. The precursor solution was deposited by a spin casting technique on the substrates. Film thicknesses of 0.1–1.0μm were achieved after heat treatment at 550°-850°C ≤4 hours. Films were analyzed as to orientation, appropriate phase, interfacial reaction and superconducting properties.

Direct Observation of Structural Defects in Laser-Deposited Superconducting Y-Ba-Cu-O Thin Films

The defect structure of in situ pulsed, laser-deposited, thin films of the high-transition temperature superconductor Y-Ba-Cu-O has been observed directly by atomic resolution electron microscopy. In a thin film with the nominal composition YBa(2)Cu(3)O(7) (123), stacking defects corresponding to the cationic stoichiometry of the 248, 247, and 224 compounds have been observed. Other defects observed include edge dislocations and antiphase boundaries. These defects, which are related to the nonequilibrium processing conditions, are likely to be responsible for the higher critical currents observed in these films as compared to single crystals.