Evolution of superconductivity by oxygen annealing in FeTe0.8S0.2 Y. Mizuguchi, K. Deguchi, S. Tsuda, T. Yamaguchi and Y. Takano EPL, 90 5 (2010) 57002 Published online: 30 June 2010 DOI: 10.1209/0295-5075/90/57002