Critical current density of high-temperature superconducting ceramics based on yttrium and thallium prepared by selfpropagating high-temperature synthesis

Y- and Tl-based superconducting ceramics samples prepared by the method of self-propagating high-temperature synthesis are studied. Critical current density value at T=77K and in the zero magnetic field Js=150A/cm2 for YBa2Cu3O7-x and Jc=63A/cm2 for Tl2Ba2Ca2Cu3Ox approximately correspond to those which can be come across in literature. The type of dependences Jc(H) is similar for two types of ceramics and proves the formation of Josephson transitions at the boundaries of granules. From the Jc(T) dependence the S-I-S-type of transitions in YBa2Cu3O7-x ceramics is determined