Novel sponge-like structure created in GdBa₂Cu₃O_7Kdceramics by hot spot

Abstract

A hot spot, which is a local area glowing orange, appears in a GdBa 2 Cu 3 O 7Kd ceramic rod when a voltage exceeding a certain value is applied to the rod at room temperature. The rod with the hot spot shows various functional characteristics that give rise to applications in devices. We found that the hot spot created a sponge-like structure in the rod. The elemental map revealed that the sponge-like structure was composed of Gd 2 BaCuO 5 grains. The hot spot is considered to decompose GdBa 2 Cu 3 O 7Kd into Gd 2 BaCuO 5 and liquid phase, and the liquid phase moves toward the periphery of the rod, leaving sponge-like structure composed of Gd 2 BaCuO 5 grains. The novel sponge-like structure created in the GdBa 2 Cu 3 O 7Kd rod by the hot spot may bring about new applications for magnetic separations of fluids. q