New tricks in the rapid quench route to high Tc materials

Abstract

High Tc materials containing Bi form glasses when quenched from their melts. These materials pass through a number of intermediate phases when furnace heated, causing chemical segregation along the way; extended annealing is then required to achieve a chemically uniform product. Chemical uniformity is preserved from the glass directly to a high Tc phase by placing the glass suddenly into a furnace at a temperature in which the final product is stable. In addition, it was found possible to hot press the glass flakes into a compact at a sufficiently low temperature without chemical segregation so that a sudden heating step will achieve the same result in bulk material.