1. Materials Characterization Division, CSIR-Central Glass and Ceramic Research Institute, 196, Raja S.C. Mullick Road, Jadavpur, Kolkata 700032, India
2. Research Institute for Sustainable Energy (RISE), TCG Centres for Research and Education in Science and Technology (TCG CREST), Sector V, Salt Lake, Kolkata 700091, India
3. Surface Physics and Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India
4. Department of Physics, University of Calcutta, 92, A.P.C. Roy Road, Kolkata 700009, India