Effect of oxygenation on levitation force in seeded melt grown single-domain YBa2Cu3Ox

The effect of oxygenation on the levitation force has been studied for single-domain YBa2Cu3Ox processed by the seeded melt growth (SMG) method. It has been found that oxygenation annealing has a pronounced effect on the levitation force only in the initial period (similar to 10 h) at 450 degrees C regardless of the sample volume. The experimental results show that the levitation force increases rapidly and begins to saturate after 10 h of oxygen anneal, indicating that the top surfaces are mainly responsible for the levitation force. Using previously published oxygen diffusion data, it has been estimated that the top surface layer (similar to 2 mm) is fully oxygenated within 10 h. As the sample's top surface is gradually lapped after oxygenation, the levitation force has been found to increase and peak at a depth of 1.5 mm. This result is consistent with the early saturation of the levitation force within a relatively shea annealing period (similar to 10 h). (C) 1997 Elsevier Science B.V.