Effects of the seed dimension on the top surface growth mode and the magnetic properties of top-seeded melt growth processed YBCO superconductors

摘要

The growth nature of YBa2Cu3O7-y (Y123) grains at the top surfaces of top-seeded melt growth (TSMG) processed YBCO superconductors was studied in respect to the dimension of Sm1.8Ba2.4Cu3.4Ox seeds. The top surface growth mode was significantly dependent on the dimensions of the seed, especially on the seed thickness. The use of thin slab-like Sm-seeds led to the nucleation of undesirable subsidiary Y123 grains at the seeded area, while such subsidiary nucleation was hardly observed when thick seeds were used. The formation mechanism of the subsidiary Y123 grains, and the effects on the levitation forces and trapped magnetic field are discussed. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 17]