YBa2Cu3O7-delta bicrystal grain boundary T-c microstructure

We use an SalphaSbetaISbetaSalpha tunneling/proximity-effect model with mea sured YBa2Cu3O7-delta (YBCO) grain boundary junction (GBJ) normalized criti cal current temperature dependence eta (T) = I-c(T)/I-c(0) to infer microst ructural transition temperature profiles T-c(x) for bicrystal GBJs with var ious misorientation angles theta, We discuss the rationale for selecting an optimum value for a numerical analysis parameter e (associated with the S, SB interface T, discontinuity). We determine the extent to which inferred T ,Gr) profiles vary with +/- 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,locations can be determined wit h less than or equal to +/-l nm precision for T-c < 60 K, Finally, we prese nt new inferred T-c(x) profiles for bicrystal junctions with <theta> = 24 d egrees and 32 degrees and compare these profiles with those of bicrystal JJ s with theta = 19 degrees and 36.8 degrees which we previously reported. Ou r inferred T,(x) profiles for these junctions exhibit a clear correlation w ith theta: as theta increases so does the extent of the grain boundary regi on with suppressed T-c. This expected result gives us confidence that our a pproach should prove useful as a tool for elucidating the structure and pro perties of high temperature superconductors.