The Bi1.7Pb0.3Sr2Ca2−xGdxCu3Oy system is investigated for different concentrations of Gd. X‐ray diffraction, electrical resistance, ac susceptibility, and dc magnetization studies are performed to study the changes in the superconducting and magnetic properties. Substitution of dilute quantities of Gd3+ for Ca2+ is found to change drastically the superconducting properties of the system. X‐ray diffraction results reveal that the volume fraction of the high‐Tc 2223 phase that is present in samples without Gd3+ (x = 0) vanishes even for x = 0.01. The Tc onset obtained from χ'ac versus T decreases from 109 to 74 K for x = 0 to 0.1, whereas the loss peak from χ″ac versus T decreases from 108 to 56 K for x = 0 to 0.05. The same behaviour is noticed from resistance measurements. The dc susceptibility studies show that except for the x = 0 sample all other samples follow a Curie‐Weiss behaviour in the normal state with Curie‐Weiss temperature θ of the order of 20 K. The data obtained are compared with our earlier results on Sm3+ substituted Bi‐2223 superconductors. The results are explained on the basis of a possible variation of hole concentration with trivalent rare earth ion substitution and also on the basis of the magnetic nature of the substituted ions.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics