Dependence of transport critical current density on sample size for ceramic RBa2Cu3O7−x (R≡Y, Ho, Gd)

Abstract
Measurements of the transport critical current density Jc were carried out on sintered and partially melted samples of YBa2Cu3O7−x , YBa2Cu3O7−x +Ag, HoBa2Cu3O7−x, and GdBa2Cu3O7−x using a four‐probe method and a contactless magnetic induction method. Results obtained by the two methods were in agreement. A pronounced dependence of Jc on sample cross‐sectional area was observed for all samples: Jc increased with decreasing cross‐sectional area. Values of Jc ranging from about 30 to 800 A/cm2 were measured depending on the preparation method and sample geometry. It is concluded that in view of the cross‐sectional area dependence, comparison of Jc for different preparations should always be made for samples of similar geometry.