Electrical and magnetic properties of Hg0.3Tl0.7Ba2Ca3Cu4O10+δ doped with Ni and Ag

Bulk superconducting samples of the type Hg0.3Tl0.7Ba2Ca3(Cu1-xRx)(4)O10+delta have been synthesized at normal pressure. The x-ray powder diffraction (XRD) for the prepared samples is studied and the lattice parameters 'a' and 'c' are calculated. The transition temperature T, determined from both electrical resistance and ac magnetic susceptibility showed a decrease in its value by increasing both Ni and Ag contents. The electrical resistance data are measured at different applied magnetic fields which show that this field does not affect the first stage of the transition, while the transition width is enlarged by increasing the magnetic field. Critical cur-rent density, calculated from the imaginary part of ac magnetic susceptibility, is well fitted according to the formula J(c)(T) = J(c)(0) [1 - T/T-c}(gamma).