[1] Penn State Univ, Altoona Coll, Dept Phys, Altoona, PA 16601 USA
[2] Penn State Univ, Mat Res Inst, University Pk, PA 16802 USA
[3] Penn State Univ, Engn, Du Bois, PA 15801 USA
[4] Penn State Univ, Dept Elect Engn, University Pk, PA 16802 USA
[5] Penn State Univ, Dept Mat Sci & Engn, University Pk, PA 16802 USA