An inter-comparison of the superconducting properties of Cu 0.5 Tl 0.5 Ba 2 (CaMg)Cu 3 O 10-δ and Cu 0.5 Tl 0.5 Ba 2 (CaMg) Cu 1.5 M 1.5 O 10-δ (M = Zn, Ni)-doped samples was undertaken. Our main objective was to determine the role of electron-phonon interactions in the mechanism of high-temperature superconductivity in these oxide superconductors. We achieved this goal indirectly by doping Zn and Ni at the Cu sites in this compound. The replacement of Cu with Zn/Ni atoms induced anharmonic oscillations due to the difference in their masses. The influence of anharmonic oscillations was enhanced due to the decreased distance between the conducting CuO 2 /MO 2 (M = Zn, Ni) planes. A comparison of zero-field-cooled (ZFC) and field-cooled (FC) magnetic moments showed suppression in the magnitude of diamagnetism with doping of Zn and Ni atoms. We suggest that the suppression in the magnetic moments arises from the difference in the atomic mass of the doped atoms in comparison with Cu atoms. With doping of Zn and Ni, the width of the magnetic hysteresis loops and their critical current density are suppresses. These decreased values in the doped samples give rise to huge anharmonic oscillations that suppress the population of phonons necessary for the mechanism of electron-phonon interactions Keywords Cu 0.5 Tl 0.5 Ba 2 (CaMg)Cu 1.5 M 1.5 O 10-δ (M=Zn, Ni) samples • infield magnetic measurements • anharmonic oscillations • electron-phonon interactions • high-temperature superconductors * Syed Hamza Safeer