The BiI.7Sbo.JSr..,.,cal.OlCuJ.IOy superconductors are prepared by
sol·gel method and the effect ofW~ and MnOz additives on their properties
are studied. Structural studies show that the find samples are homogeneous
and are mainly composed of 2223 and lower percents of 2212 phases.
Analysis ofthe X-ray diffraction patterns indicate that the penetration of~
ions into superconducting phase considerably increases for more than 2 wt%
additives. Also. the penetrating ~ ions preferentially occupy 4e and 2a
crystallographic sites of eu atoms. The electrical measurements show that
the best superconducting properties obtain for the sample with I wt% of
WOJ additive, while superconductivity is weakened for higher amounts of
WO,. For the sample with O.S wt% of MnOz additive, the best
superconducting properties are obtained after sintering at 830 OC.