GROWTH OF NUCLEATION SITES ON PB-DOPED BI2SR2CA1CU2O8+DELTA

In the growth of Bi2Sr2Ca2Cu3O10+delta, a from mixed powders of Pb-dop ed Bi2Sr2Ca1CU2O8+delta and other oxides, it has been discovered that a dense array of hillocks or mesas grow at the interface between a Ag overlay and Pb-doped Bi2Sr2Ca1Cu2O8+delta grains during the ramp up to the reaction temperature. As viewed in an environmental scanning elec tron microscope, the Ag coated grains develop a texture that looks lik e ''chicken pox'' growing on the grains at about 700 degrees C. These hillocks are about 100 nm across and are spaced at about 500 to 1000 n m. If there is no Ag, this texture does not develop. Preliminary measu rements indicate that the hillocks are a recrystallization of (Bi,Pb)( 2)Sr2Ca1CU2O8+delta and are definitely not a Pb rich phase. (C) 1996 A merican Institute of Physics.