[1] Univ Hyderabad, CASEST, Sch Phys, Hyderabad 500046, Telangana, India
[2] Univ Nacl Mayor San Marcos, Fac Ciencias Fis, Lab Ceramicos & Nanomat, Lima 14, Peru
[3] Vellore Inst Technol, Sch Adv Sci, Dept Chem, Vellore 632014, Tamil Nadu, India
[4] Univ Cambridge, Dept Phys, Cavendish Lab, Cambridge CB3 OHE, England
[5] Northeastern Univ, Sch Mat Sci & Engn, Shenyang 110819, Liaoning, Peoples R China