Effect of Sn on the Superconductivity of the DyBa2Cu3O7-δ System

Abstract
The tin-substituted superconducting system DyBa2Cu3-3x Sn3x O y was investigated from x=0.025 to x=0.4 by measurements of electrical resistivity and ac susceptibility, X-ray diffraction, and Mössbauer spectroscopy. It was found that the substitution of Cu by Sn does not affect the zero-resistance temperature until x≥0.25 and results in the presence of a second phase. An anomaly in the temperature dependence of the Mössbauer recoil-free fraction near 70 K was observed for the sample with nominal composition DyBa2Sn3O y .