  This paper aims to study Na doping in Bi-2212 superconducting ceramics.
Na-doped Bi-2212 samples powders with a Bi2-uSr2-vCa1-wCu2-xNayOz stoichiometry
are prepared by means of thermal treatments. The intended Na substitution
level, y, is fixed at 0.3. The initial content of the other ions is adopted so
that Na substitution on one crystallographic site only is expected. Samples are
characterized by electrical properties, X-ray diffraction analysis (XRD) and
Energy Dispersive X-ray analysis (EDX). The influence of Na on the crystal
chemistry and phases compatibility for 2212 materials is emphasized. Electrical
resistivity results show that the critical temperature is independent of the
sample initial stoichiometry. In some cases the production of a Bi-2223 phase
is however enhanced.
