THE EFFECT OF CO2 IN THE PROCESSING ATMOSPHERE OF YBA2CU3OX

Processing atmospheres of up to 1% CO2-doped oxygen were employed to study the effect of carbon contamination on the superconducting properties of YBa2Cu3Ox. While 100 p.p.m. CO2 did not show any adverse effect, Jc decreased drastically in 1000 p.p.m. CO2. The sample processed in 1% CO 2-doped oxygen was non-superconducting at 77 K. X-ray diffraction indicated a tetragonal structure and the oxygen content of this sample was found to be 6.65 by iodometric titration. The microstructural appearance suggests that a continuous grain boundary film may have formed which is less pervious to oxygen at the lower temperatures used for annealing during sample preparation.