The phase transformations and structural changes occurring during initial h
eating and annealing of an Ag-clad high-T-c superconducting tape of the (Bi
, Pb)(2)Sr2Ca2Cu3Ox type are investigated. The annealing takes place in air
at an operating temperature of 835 degrees C. Using x-ray diffraction with
100 keV photons from a synchrotron source the concentration, stoichiometry
and texture of the dominant phases are monitored in situ during the transf
ormation of BiSCCO from (Bi, Pb)(2)Sr2CaCu2Ox, (2212) to (Bi, Pb)(2)Sr2Ca2C
u3Ox, (2223). In addition, information on grain size and residual strain is
obtained. During heating the (Ca, Sr)(2)PbO4 additive decomposes between 7
00 degrees C and 820 degrees C. Simultaneously, the residual strain in the
2212 grains is relieved and the c-axis alignment of the grains is substanti
ally improved. Moreover, the Pb content of the 2212 structure increases con
tinuously. We interpret these results as being related to a temperature-dep
endent solubility limit of Pb in 2212, leading to a substantial grain growt
h of the phase. Above 812 degrees C 2212 partly decomposes to form (Ca, Sr)
(2)CuO3 and a liquid. At the operating temperature 2212 and (Ca, Sr)(2)CuO3
react with the liquid to form 2223. During the conversion the 2212 lattice
expands, indicating that the remaining 2212 grains contain less and less P
b. The final 2212 and 2223 textures are approximately identical, and Avrami
plots of the transformation kinetics give exponents m in the range 1 < m <
2. During the annealing the 2212 linewidth is constant, implying that ther
e is neither strain nor finite-size broadening of the 2212 peaks during the
transformation. This points to a transformation mechanism where only a few
2212 grains transform at a given time. Implications of these findings are
discussed in relation to intercalation and nucleation-and-growth models.