1. G.R.D Center for Materials Research, PSG College of Technology , Coimbatore - 641004 , India
2. Department of Physics, Dr. N.G.P. Institute of Technology , Coimbatore - 641048 , India
3. Department of Physics , PSG College of Technology , Coimbatore - 641004 , India
4. Department of Materials Science , Central University of Tamil Nadu , Thiruvarur - 610 005 , India