The Influence of the Bulk Density on the Intergranular Properties of   YBa2Cu3-xFexOy (0<x<0.01) Ceramics
  The influence of the bulk density of YBa2Cu3-xFexOy (0 < x < 0.01) ceramics on the intergranular superconducting (SC) properties was studied using the temperature dependence of AC magnetic susceptibility measurements. It was found that the simultaneous variation of the sample's density and the iron impurity concentration does not influence effectively the onset temperature of the superconducting state Tc(on). While only increasing of the sample's density shifts the intergranular hysteresis losses peak temperature Tm(J) to the lower values which connects with the decreasing of the Josephson magnetic vortices pinning role. It was established that the shielding capability and Tm(J) display a plateau with X in the 0.003 < X < 0..007 region which is due to the monotonous decrease of the sample's density. It was shown that the shielding capability at the T=78K for the sample with 3.8g/cm3 is two times higher than that for the sample with the density of 5.0g/cm3. The possible interpretations of the observed results are discussed. 
S. K. Nikogosyan, A. A. Sahakyan, H. N. Yeritsyan, V. A. Grigoryan