Low-temperature magnetic and microwave studies of Gd0.95Ba2Cu3.05O7??: Agx composites

Abstract

Gd[sub 0.95]Ba[sub 2]Cu[sub 3.05]O[sub 7-[delta]]: Ag[sub x] (x = 0.0, 0.02, 0.04, 0.06) ceramic superconducting samples were prepared by a co-precipation technique using organic carbonates in the presence of stable polymers. The room-temperature normal-state resistivity decreases with Ag addition. However, T[sub c] and crystallographic parameters were unaffected. Low-temperature (4.2 K) magnetic and electrical transport studies in high magnetic fields (5 T) reveal that the addition of Ag into the Gd[sub 0.95]Ba[sub 2]Cu[sub 3.05]O[sub 7-[delta]] (GBCO) enhances the magnetic critical current density (J[sub mc]), volume pinning force (F[sub p]), flux explosion, and transport critical current density (J[sub tc]). Microwave-induced dc voltage studies show the reduction in the total number of weak links between superconducting GBCO grains with increase in Ag concentration. The flux creep rate was also increased with increase in Ag concentration in GBCO resulting in stronger pinning potential. The increase in J[sub mc], J[sub tc], and, hence, F[sub p] with Ag addition in the GBCO suggests the creation of an SNS-type proximity junction at the intergrannular region and stronger Josephson current paths between the superconducting intergrains, which may be due to the physical densification and reduction of the total number of weak links by Ag addition into the GBCOmore » superconducting system. 26 refs., 6 figs., 1 tab.« less