[1] Dr NGP Inst Technol, Dept Chem, Coimbatore 641048, Tamil Nadu, India
[2] KPR Inst Engn & Technol, Dept Phys, Coimbatore 641407, Tamil Nadu, India
[3] PSGR Krishnammmal Coll Women, Dept Chem, Coimbatore 641004, Tamil Nadu, India
[4] Univ Patras, Dept Mat Sci, Patras 26500, Greece