Study of Oxygen Isotope Effect in Pr, Ca, And Zn Doped Superconductivity YBa2Cu3O7-Δ

The oxygen isotope effect in Pr, Ca, and Zn doped superconductivity YBa2Cu3O7-δ was investigated. Pr and Ca substitute predominantly at the Y site while Zn goes into the Cu plane site. The shift in critical temperature (?TC) between samples oxygenated in 18O and 16O was obtained via dc resistance measurements, and low field dc magnetization and ac susceptibility measurements in a SQUID magnetometer. Confirmation of the substitution of the oxygen was a achieved with Raman and SIMS measurements. The Pr, Ca and Zn substituted change TC of the superconductor in different ways. Increasing Pr concentrations lower TC and increase ?TC with the isotope coefficient, α, approaching1?2. The additions of ca reduces the size of both ?Tc and α. Both exhibit a small parabolic effect with increasing Ca substitution. An increase in Zn substitution. An increase in Zn substituted lowers TC but ?TC remains nearly constant, or perhaps gets slightly smaller, with α increasing to approximately1?3.