Artículos de revistas
Structural study of thin films prepared from tungstate glass matrix by Raman and X-ray absorption spectroscopy
Fecha
2008-06-30Registro en:
Applied Surface Science. Amsterdam: Elsevier B.V., v. 254, n. 17, p. 5552-5556, 2008.
0169-4332
10.1016/j.apsusc.2008.02.107
WOS:000256099500046
6446047463034654
2998503841917815
0000-0003-3286-9440
Autor
Universidade Federal de Alfenas (UNIFAL)
Universidade Estadual Paulista (Unesp)
Universidade de São Paulo (USP)
Institución
Resumen
Thin films were prepared using glass precursors obtained in the ternary system NaPO(3)-BaF(2)-WO(3) and the binary system NaPO(3)-WO(3) with high concentrations of WO(3) (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 L(I) and L(III) absorption edges. XANES investigations showed that tungsten atoms are only sixfold coordinated (octahedral WO(6)) and that these films are free of tungstate tetrahedral units (WO(4)). In addition, Raman spectroscopy allowed identifying a break in the linear phosphate chains as the amount of WO(3) increases and the formation of P-O-W bonds in the films network indicating the intermediary behavior of WO(6) 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 W-O and W=O terminal bonds and a progressive apparition of W-O-W bridging bonds for the most WO(3) concentrated samples (above 40% molar) attributed to the formation of WO(6) clusters. (C) 2008 Elsevier B.V. All rights reserved.