1. College of Materials Science and Engineering, Qingdao University, Qingdao 266071, Shandong, P. R. China
2. College of Textiles and Clothing, Qingdao University, Qingdao 266071, Shandong, P. R. China
3. Department of Physics, COMSATS University Islamabad, Lahore Campus, Lahore, 54000, Pakistan