An investigation of the transformation from Bi2Sr2CaCu2O8 to Bi2Sr2Ca2Cu3O10

The phase stabilization of the (Bi1.6+yPb0.4)Sr2-xCa2+x Cu3O2 system has been studied in the composition ranges 0 less than or equal to x less than or equal to 0.25 and 0 less than or equal to y less than or equal to 0.4 by X-ray powder diffraction, magnetic susceptibility, and electrical resistivity measurements. The transformation from Bi2Sr2CaCu2O8 to Bi2Sr2Ca2Cu3O10 is a slow process and the Bi2Sr2Ca2Cu3O10 phase can be stabilized by a small excess of Bi and partial substitution of Sr by Ca. A final, nearly pure Bi2Sr2Ca2Cu3O10 phase (T-c = 107 K, Delta T-c = 6-8 K) was obtained after 200 h annealing, Both X-ray analysis and magnetic susceptibility measurements appear to be excellent methods for monitoring such superconducting phases. (C) 1998 Academic Press.