Rapidly Quenched Bi- and Tl- Containing High T sub c Compositions

Twin roller quenching from the melt at 100 to 200K above the melting point with a quench rate of ~ 10 sup 7 K sec sup -1 was used to prepare pure glass of several high T sub c compositions, including the Bi 2212, 4434, and 2223 stoichiometries, in the sequence Bi, Sr, Ca, Cu. Differential thermal analysis (DTA) in O sub 2 and N sub 2 and thermogravimetry (TGA) in O sub 2 as well as powder X-ray diffraction (XRD) and squid magnetometry were used to characterize the glasses and their crystallization products on heating.