Effects of Y doping on the (Hg,Re)-1212 superconductor properties

Hg0.82Re0.18Ba2Cax-1YxCu2O6+d samples were prepared with different yttrium (Y) content (0.05 < x < 0.55). The X-ray diffraction analysis has revealed that there is no Y-precursor precipitation, however, the n = 3 phase has appeared for x < 0.15. The ac magnetic susceptibility measurements have shown that Tc was reduced with increasing the Y content. Moreover, the Tc values can be fitted as an approaching parabolic dependence on yttrium content. In our opinion, this behavior is understood according to the phenomenological model charge-transfer, i.e., the Y doping changed the carrier in the inner layer and induced an overdoped, which reduced the Tc value