title: Raman spectrum, quantum mechanical calculations and vibrational assignments of (95% alpha-TeO2/5% Sm2O3) glass.
abstract: Chozen system of tellurite glasses doped with rare earth oxides (95% alpha-TeO(2)+5% Sm2O3) was prepared by melt quenching. Consequently, the Raman spectrum (150-1250 cm(-1)) of the modified tellurite have been recorded. As a continuation to our normal coordinate analysis, force constants and quantum mechanical (QM) calculations for tbp TeO4(4-) (triagonal bipyramid, C(2v)) and TeO(3+1); Te2O7(6-) (bridged tetrahedral), we have carried out ab initio frequency calculations for tpy TeO3(2-) (triagonal pyramidal, C(3v) and C(s)) and tp TeO3(2-) (triagonal planar, D(3h)) ions. The quantum mechanical calculations at the levels of RHF, B3LYP and MP2 allow confident vibrational assignments and structural identification in the binary oxide glass (95% alpha-TeO2 +5% Sm2O3). The dominant three-dimensional network structures in the modified glass are triagonal pyramidal TeO3 with minor features of short range distorted tbp TeO4 and bridged tetrahedral unit of TeO(3+1), leading to a structure of infinite chain. Therefore, alpha-TeO2/Sm2O3 (95/5%) glass experience structural changes from TeO4 (tbp); Te2O7 (TeO(3+1))-->TeO3 (tpy).
authors.affiliation: Department of Physics, Faculty of Science, Al-Azhar University, Nasr City 11884, Cairo, Egypt.
authors.forename: I
authors.initials: I
authors.lastname: Shaltout
authors.forename: Tarek A
authors.initials: TA
authors.lastname: Mohamed
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D008432:Mathematical Computing; D011789:Quantum Theory; D013059:Spectrum Analysis, Raman; D014732:Vibration
chemical_list: C522621:alpha-TeO2-Sm2O3 glass