Containerless solidification of YBa₂Cu₃O_7-x in a drop tube

Abstract

YBa₂Cu₃O_7-x was molten and resolidified by a containerless process under free-fall conditions in a drop tube. The resulting samples revealed four different microstructures originating either from a “high-temperature melt” (T_m ≥ 1550 K) or from a ”low-temperature melt” (1288 K ≤ T_m ≤ 1550 K). All structures exhibited very fine, homogeneously dispersed structural constituents. One of these microstructures is not compatible with actual equilibrium phase diagrams and implies the kinetic suppression of the nucleation of both the Y₂BaCuO₅- and the Y₂O₃-phase.