Internal friction and Young’s modulus in the Bi(Pb)-Sr-Ca-Cu-O superconductor

Measurements of internal friction and resonant frequency in the kHz range have been conducted in Bi(Pb)-Sr-Ca-Cu-O superconductors between 80 and 300 K. The specimens are of pure low-Tc 2:2:1:2 phase, pure high-Tc 2:2:2:3 phase, or binary phase. The experimental results show that the internal-friction spectra of Y-Ba-Cu-O, Bi-Sr-Ca-Cu-O, and Bi(Pb)-Sr-Ca-Cu-O superconductors are obviously different and are affected by the preparation conditions of the specimens. This may be related to the difference of the oxygen deficiency and the ions with mixed valence in the specimens. There should not always be an internal-friction peak near Tc associated with the superconducting transition.