Orientation distribution of grain planes in polycrystal Ag/Bi-2223 tape

For polycrystalline Ag/Bi-2223 tapes, the preferential orientation of grains is a very important issue. The platelike grains in the tapes are generally believed in a high-order alignment. However, microstructural observation by SEM shows that the grain alignment is far from perfect. Theoretically, upper critical field, H-c2, for H parallel to ab plane and 0 axis was calculated form the relation of IM(H). However, the ratio of H-c2 ((H//ab)) to H-c2(H//c) depends on the angle (theta) between the ab plane of grains and the broad surface of the tapes; Based on the ratio, the orientation distribution of grains is obtained. The results show that grains in Ag/Bi-2223 tapes can grow with ab plans at any angle between 75 degrees > theta > -75 degrees, but no grain can grow with its ab plane perpendicular to the tape broad surface. The overall distribution is that: > 90% grains orient in the angle range of /theta/ < +/- 75 degrees, about 5% grains at +/- 75 degrees less than or equal to /theta/ less than or equal to +/- 85 degrees, and no grains at /theta/ > +/- 85 degrees.