Retraction to: J Supercond Nov Magn (2015) 28:

1455–1459

DOI 10.1007/s10948-014-2894-4

This article has been retracted at the request of the Co-Editors because it has been found that the authors have duplicated substantial parts from the following article: Hasnain, S. M., Mumtaz, M., Khan, Nawazish A.: Optimum Synthesis Temperature of (Cu 1−xTl x)Ba 2Ca 3Cu 4O12−δ Superconductor. Journal of Superconductivity and Novel Magnetism 24, 1653–1657 (2011). doi:10.1007/s10948-010-1073-5.

Corresponding author M. Tariq confirms that Muhammad Zubair, Teaching Research Associate in the Department of Physics at the International Islamic University, Islamabad, Pakistan, is not a co-author on the retracted paper.