Microstructural studies of Tl2Ba2Ca2Cu3Ox thin films on LaAlO3 and MgO substrates.

Tl(2)Ba2Ca(2)Cu(3)O(x) thin films have been fabricated on (001) LaAlO3 and (001) MgO substrates. Films grown on LaAlO3 have T-c=112K and R-s(80K, 10GHz)=0.2m Ohm, while films on MgO have T-c=117K and R-s(80K; 10GHz)=0.7m Ohm. The grain size and alignment of the Alms has been investigated using X-ray diffraction, Scanning Electron Microscopy and Electron Backscattered Diffraction. We show evidence for a markedly higher in-plane angular spread for films on MgO and believe that for films grown on this substrate the lowest achievable values of R-s are limited by disorder in the in-plane alignment of the TBCCO film caused by the large lattice mismatch between the materials.