Preparation of spherical particles of Ba₂YCu₃O_7−x superconductor by plasma spraying

Abstract

Ground angular powder of pre-synthesized Ba₂YCu₃O_7−x was introduced into a high-temperature plasma jet flame with argon as the plasma gas. Morphological changes in the particles and in microstructural features, as well as phase changes, were observed on the plasma-sprayed powder. Spherical particles with various surface topographies were formed: smooth surface with fine grain structure; spiky surface; and polygonal surface structure. X-ray phase analysis showed that the plasma-sprayed powder was a mixture of solidified crystalline and amorphous phases from the liquid state, while the metallic composition of the starting powder was retained. The plasma-sprayed particles were subsequently annealed for 20 to 80 h in air at temperatures up to 1123 K. The superconductor phase was recovered by this heat treatment, while the particles became porous with morphological changes in surface topography.