Simple die pressing for making artificial holes in single-grain Gd1.5Ba2Cu3O7−y superconductors

• Published in: Superconductor science & technology Vol. 25; no. 10
• Main Authors: Kim, K-M, Park, S-D, Jun, B-H, Ko, T K, Kim, C-J
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.10.2012; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cuprates superconductors (high tc and insulating parent compounds); Exact sciences and technology; Mechanical and acoustical properties; Physical properties of thin films, nonelectronic; Physics; Superconductivity; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Magnetic flux; Metallic conduction; Magnetic forces; Cracking; Mechanical properties; Sintering; Materials drilling; Growth mechanism; Pressing; High-Tc superconductors; Barium Copper Gadolinium Oxides Mixed; Powder compaction; Thermal conductivity; Surface area; Diffusion; Crystal growth from melts; Melts; Magnetic levitation
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/25/10/105016

The presence of artificial holes in single-grain REBa2Cu3O7−y (RE123, RE: rare-earth elements) bulk superconductors can facilitate oxygen diffusion into superconducting grains through the increased surface area. In addition to the enhancement of oxygen diffusion, the mechanical properties and thermal conductivity of bulk superconductors can be improved by filling holes with a metallic conductive phase. This study presents a new and simple hole-making process for single-grain RE123 bulk superconductors. Artificial holes 3 or 5 mm in diameter were made for Gd1.5Ba2Cu3O7−y (Gd1.5) powder compacts prior to the sintering/melt growth process using specially designed pressing dies. The die pressing neither induced cracking in powder compacts nor influenced thermal procedures for the Gd123 growth. Single-grain Gd1.5 bulk superconductors with holes were successfully fabricated by a top-seeded melt growth (TSMG) process using Gd1.5 powder compacts with holes. The die pressing was proven as a time-saving process in comparison with the conventional method which makes holes in sintered or melt-processed hard bodies by mechanical drilling. The detailed fabrication process of single-grain Gd1.5 bulk superconductor with holes, magnetic levitation forces, and magnetic flux density, estimated for the single-grain Gd123 bulk superconductors with holes, are reported.