Angular distribution of crystal grains in polycrystal Bi-2223/Ag tape

Grain alignment in Bi-2223/Ag superconducting tapes was investigated by measuring critical current density, J c (T), in applied magnetic field (H//ab and H//c). Based on Bean model, the magnetization intensity M(T,H) was determined from the data of J c (H,T). Upper critical field, H c2 , for H parallel to ab plane and c-axis was then theoretically calculated from the relation of M(H). Based on the fact that the ratio of H c2(H//ab) to H c2(H//c) depends on the angle θ between the ab plane of grains and the broad surface of the tape, the orientation distribution of grains was determined. The calculated results showed that ab planes of grains in Bi-2223/Ag tapes may have an orientation angle at any value between 75°>θ>-75°. Few grains can have an angle in the region of 75°>/θ/ >85° and no grain can orient with its ab plane perpendicular to the broad surface of the tape. This means that in polycrystalline Bi-2223/Ag tapes grains tend to have certain preferential orientation, but do not tend to form a perfect orientation. The distribution of grain orientation has significant effect on critical current density (J c ) and J c behaviour in applied magnetic field.