The isostructural phases in Bi-2212-type HTSC were studied by structur
al and optical methods. The epitaxial intergrowth was shown to be a fe
ature typical of single crystals composed of several isostructural pha
ses. The physical properties of the multi-phase samples were interpret
ed on the basis of reference mono-phase samples. A presence of the int
ergrowth interface was assumed to be responsible for particular featur
es in multi-phase samples.