1. Centre for Materials for Electronics Technology (C-MET), RoHS Laboratory, IDA, Phase III, Cherlapally, Hindustan Cables Limited (Post), Hyderabad 500051, India (Corresponding author), e-mail: rambabu32@rediffmail.com
2. CSIR-National Geophysical Research Institute, Hyderabad 500007, India
3. Centre for Materials for Electronics Technology (C-MET), RoHS Laboratory, IDA, Phase III, Cherlapally, Hindustan Cables Limited (Post), Hyderabad 500051, India
4. Ministry of Electronics & Information Technology (MeitY), 6, CGO Complex, Lodhi Road, New Delhi 110003, India