1. Department of Physics , Dr. B. R. Ambedkar Open University , Jubilee Hills , Hyderabad , Telangana , India
2. Department of Physics , Acharya Nagarjuna University , Nagarjuna Nagar , Guntur , Andhra Pradesh , India
3. Department of Nanotechnology , Acharya Nagarjuna University , Nagarjuna Nagar , Guntur , Andhra Pradesh , India