The effects of the homogenizing procedure and annealing treatment on superconducting transition temperature, Tc, were investigated for Zn-substituted YBa2Cu3O7-δ. Samples of YBa2Cu3-xZnxO7-δ (x = 0.00, 0.02, 0.05 and 0.10) were prepared under different conditions. It was found that additional pulverization and re-sintering lower Tc in Zn-substituted samples. Moreover, annealing in reduced atmosphere prior to the final oxygenation further decreases Tc, resulting in the lowest value (Tc = 46 K for x = 0.10) among Tc's ever reported for Zn-substituted YBa2Cu3O7-δ. This suggests that Zn at the Cu-O chain site moves to the CuO2 plane by annealing samples in reduced atmosphere. Comparison of Tc-suppression effects by Zn and Ni is also discussed.
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