Oxygen Isotope Effect in High-Temperature Oxide Superconductors

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Science  11 Dec 1987:
Vol. 238, Issue 4833, pp. 1558-1560
DOI: 10.1126/science.238.4833.1558


The effect of oxygen isotope substitution on the superconducting transition temperature, Tc, has been measured for BaBi0.25Pb0.75O3 (Tc, ≈ 11 K) and Lal1.85 Ca0.15CuO4 (Tc ≈ 20 K), and is compared to the shifts observed for La1.85Sr0.15CuO4 (Tc ≈ 37 K) and YBa2Cu3O7 (Tc ≈ 92 K). For all four materials, the transition temperature is shifted to lower temperature upon substitution of oxygen-18 for oxygen-16. The observed shifts demonstrate that phonons are involved in the electron-pairing mechanism in these oxide superconductors.