YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// bicrystal grain boundary T/sub c/ microstructure

We use an S/sub /spl alpha//S/sub /spl beta//IS/spl beta//sub S/spl alpha// tunneling/proximity-effect model with measured YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) grain boundary function (GBJ) normalized critical current temperature dependence /spl eta/(T)=I/sub c/(T)I/sub c/(O) to infer microstructural transition temperature profiles T/sub c/(x) for bicrystal GBJs with various misorientation angles /spl theta/. We discuss the rationale for selecting an optimum value for a numerical analysis parameter /spl epsi/ (associated with the S/sub /spl alpha//S/sub /spl beta// interface T/sub c/ discontinuity). We determine the extent to which inferred T/sub c/(x) profiles vary with /spl plusmn/20% rms deviations from nominal values for the fixed input parameters whose a priori values are not precisely known. This sensitivity analysis shows that specified T/sub c/ locations can be determined with /spl les//spl plusmn/1 nm precision for T/sub c/<60 K. Finally, we present new inferred T/sub c/(x) profiles for bicrystal junctions with /spl theta/=24/spl deg/ and 32/spl deg/ and compare these profiles with those of bicrystal JJs with /spl theta/=19/spl deg/ and 36.8/spl deg/ which we previously reported. Our inferred T/sub c/(x) profiles for these functions exhibit a clear correlation with /spl theta/: as /spl theta/ increases so does the extent of the grain boundary region with suppressed T/sub c/. This expected result gives us confidence that our approach should prove useful as a tool for elucidating the structure and properties of high temperature superconductors.