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

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.