SYNTHESIS AND PROPERTIES OF TL-BA-CA-CU-O SUPERCONDUCTORS

We review the synthesis methods and properties of single crystal, powd er, and thin film T1BaCaCuO high-temperature superconducting (T1-HTS) materials. With transition temperatures greater than or equal to 100 K for several compounds, T1-HTS materials present real opportunities fo r applications above 77 K. Experiments using (1) single crystals: dete rmined precise structural parameters and identified the complex T1(1+) -T1(3+) equilibrium model; (2) powders: studied the complex thermodyna mic phase diagram; and (3) epitaxial films: studied fundamental proper ties such as electron pair symmetry and the effect of controlled extri nsic defects on flux pinning strength, as well as providing the large- area surfaces required for device applications.