[1] Univ Fed Sergipe, Dept Fis, Grp Nanomat Funcionais GNF, Campus Univ, BR-49100000 Itabaiana, SE, Brazil
[2] Inst Fed Sergipe, Coordenadoria Fis, BR-49400000 Lagarto, SE, Brazil
[3] Univ Fed Sergipe, Dept Fis, Campus Univ, BR-49100000 Sao Cristovao, SE, Brazil
[4] Keele Univ, Sch Chem & Phys Sci, Keele ST5 5BG, Staffs, England