1. Nanomaterials Research Group, Physics Division PINSTECH Islamabad 44000 Pakistan
2. College of Chemistry and Chemical Engineering Northeast Petroleum University Daqing 163318 P. R. China
3. School of Resources and Materials Northeastern University at Qinhuangdao Qinhuangdao 066004 P. R China
4. Materials Division PINSTECH Islamabad 44000 Pakistan