Oxygen content and disorder effects on the critical current density in YBa2Cu3Ox

Magnetic measurements have been used to evaluate the critical current densi ty J(c) for YBa2Cu3Ox samples with various oxygen content (x) and, for part ially oxygenated samples (x similar to 6.5), with different degrees of oxyg en disorder. The current density has been expressed in terms (T/T-c)(-delta ), where delta decreases linearly with x for x < 6.6 and becomes constant f or 6.6 < x < 7. Moreover, the variation in T-c with oxygen content has been used to represent J(c) as J(c) = J(o) (x/T-c)(-n), where J(o) is almost co nstant and n is temperature dependent. At a given temperature ratio (T/T-c) , the oxygen disorder enhances the critical current density and weakens its field dependence. It is argued that the increased number of Cu(1) + 3O clu sters with increasing disorder may cause additional pinning centres and aff ect the J(c) behaviour.