Oxygenation Thermogravimetry of TSMG YBCO Bulk Superconductor

The oxygenation of TSMG YBCO bulk superconductor at 450degC was studied by thermogravimetry and optical microscopy. It is shown that the observed deviation from the parabolic dependence of the sample weight on time can be related to cracking induced during the first oxygenation of as grown tetragonal sample. The development of cracks along the {100} and {001} planes during oxygenation, play a crucial role in shortening the oxygenation time. The oxygenation time could be controlled by the spacing of the cracks along {100} planes (c-cracks) that act as boundaries saturated on oxygen. It is shown that, using the c-crack spacing as the sample size for bulk oxygen diffusion, the calculated oxygenation time is in good agreement with thermogravimetric measurements.