Structural study of thin films prepared from tungstate glass matrix by Raman and X-ray absorption spectroscopy |
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Authors: | Bianca Montanari,Sidney J.L. Ribeiro,Gaë l Poirier,Má ximo S. Li |
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Affiliation: | a Departamento de Química Geral e Inorgânica, Instituto de Química, UNESP, CP 355, CEP 14800-900 Araraquara, SP, Brazil b Departamento de Ciências Exatas, UNIFAL-MG, CEP 37130-000 Alfenas, MG, Brazil c Instituto de Física, USP, CP 369, CEP 13560-970 São Carlos, SP, Brazil |
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Abstract: | Thin films were prepared using glass precursors obtained in the ternary system NaPO3BaF2WO3 and the binary system NaPO3WO3 with high concentrations of WO3 (above 40% molar). Vitreous samples have been used as a target to prepare thin films. Such films were deposited using the electron beam evaporation method onto soda-lime glass substrates. Several structural characterizations were performed by Raman spectroscopy and X-ray Absorption Near Edge Spectroscopy (XANES) at the tungsten LI and LIII absorption edges. XANES investigations showed that tungsten atoms are only sixfold coordinated (octahedral WO6) and that these films are free of tungstate tetrahedral units (WO4). In addition, Raman spectroscopy allowed identifying a break in the linear phosphate chains as the amount of WO3 increases and the formation of POW bonds in the films network indicating the intermediary behavior of WO6 octahedra in the film network. Based on XANES data, we suggested a new attribution of several Raman absorption bands which allowed identifying the presence of WO− and WO terminal bonds and a progressive apparition of WOW bridging bonds for the most WO3 concentrated samples (above 40% molar) attributed to the formation of WO6 clusters. |
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Keywords: | 61.43.Er 68.60.&minus p 74.25.Gz |
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