1. College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, P.R. China
2. Department of Physics, Sri Vidya Mandir Arts and Science College, Katteri, Uthangarai, Krishnagiri, Tamil Nadu 636902, India
3. Centre for Advanced Materials and Industrial Chemistry (CAMIC), RMIT University, Melbourne, VIC 3000, Australia