1. a Materials Science and Engineering Program , Mechanical Engineering Department, Louisiana State University , Baton Rouge, Lousiana 70803, USA
2. b Texas Center for Superconductivity and Advanced Materials and Department of Physics , University of Houston , Texas 77204, USA
3. c Materials Science and Engineering Program , Mechanical Engineering Department, Louisiana State University , Baton Rouge, Lousiana 70803, USA E-mail: