Preliminary investigation of Indium substitution on Sr-site of Bi2Sr2Ca2Cu3O10+δ superconductor
Nominal amounts of Indium from 0.05 to 0.3 are found suitable to Bi2Sr2CaCu2O8+δ (2212) and further dissociate Bi2Sr2Ca2Cu3O10+δ (2223) into Bi2Sr2CaCu2O8+δ (2212) (2212), Bi2Sr2CuO6+δ (2201) and Sr-Cu-O phase when substituted in the Sr-site. In the two heat treatment profiles used, calcination at 837°C for 24 hours and sintering at 856°C 48 hours only produced around ~10% 2223. No In-based impurities were found as all diffraction peaks are accounted for the Bi-Sr-Ca-Cu-O system. As for calcination at 800°C for 24 hours and sintering at 837°C for 48 hours, the most prominent phase is the 2212 phase for about ~63.6%. Regardless of the heat treatment parameters used, increasing Indium content causes a decrease in Tc of the 2212 phase and have been detrimental to the formation of 2223 phase disappearing at nominal Indium amount of 0.3. In general, Indium inhibits the formation of 2223 by preventing the reaction of 2201, 2212 and impurities as observed in diffraction measurements.