Transition range viscosity of rapidly quenched Bi-Ca-Sr-Cu-O glasses

As a precursor of high Tc superconductors, glasses in the system BixCaSrCu2Ow (x=1.5,2.7) have been prepared using twin-roller and metal-plate quenching procedures. Transition range viscosities have been measured on samples as thin as 0.02 mm using the beam-bending method with a technical modification. From the viscosity data, the system Bi-Ca-Sr-Cu-O can be characterized as a ‘‘fragile’’ liquid like the ZrF4-based fluorides. The possibility of drawing fibers of high Tc superconductor precursors is discussed on the basis of the temperature dependence of viscosity.