1. Department of Polymer Science and Technology, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, India
2. Department of Electronic Science, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, India
3. Department of Ceramic Engineering, Indian Institute of Technology (BHU), Varanasi 221005, Uttar Pradesh, India
4. Center for Research in Nano Science and Nano Technology, University of Calcutta, JD-2, Sector III, Salt Lake City, Kolkata 700106, India