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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Cluster Coordination and Photoluminescence Properties of alpha-Ag2WO4 Microcrystals

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Author(s):
Cavalcante, L. S. [1, 2] ; Almeida, M. A. P. [3] ; Avansi, Jr., W. [2] ; Tranquilin, R. L. [3] ; Longo, E. [3, 2] ; Batista, N. C. [1] ; Mastelaro, V. R. [4] ; Siu Li, M. [4]
Total Authors: 8
Affiliation:
[1] UESPI CCN, Dept Quim, BR-64002150 Teresina, PI - Brazil
[2] Univ Estadual Paulista, BR-14801907 Sao Paulo - Brazil
[3] Univ Fed Sao Carlos, BR-13565905 Sao Paulo - Brazil
[4] Univ Sao Paulo, IFSC, BR-13560970 Sao Paulo - Brazil
Total Affiliations: 4
Document type: Journal article
Source: Inorganic Chemistry; v. 51, n. 20, p. 10675-10687, OCT 15 2012.
Web of Science Citations: 97
Abstract

In this paper, we report our initial research to obtain hexagonal rod-like elongated silver tungstate (alpha-Ag2WO4) microcrystals by different methods {[}sonochemistry (SC), coprecipitation (CP), and conventional hydrothermal (CH)] and to study their cluster coordination and optical properties. These microcrystals were structurally characterized by X-ray diffraction (XRD), Rietveld refinements, Fourier transform infrared (FT-IR), X-ray absorption near-edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) spectroscopies. The shape and average size of these alpha-Ag2WO4 microcrystals were observed by field-emission scanning electron microscopy (FE-SEM). The optical properties of these microcrystals were investigated by ultraviolet-visible (UV-vis) spectroscopy and photoluminescence (PL) measurements. XRD patterns and Rietveld refinement data confirmed that alpha-Ag2WO4 microcrystals have an orthorhombic structure. FT-IR spectra exhibited four IR-active modes in a range from 250 to 1000 cm(-1). XANES spectra at the W L-3-edge showed distorted octahedral {[}WO6] clusters in the lattice, while EXAFS analyses confirmed that W atoms are coordinated by six O atoms. FE-SEM images suggest that the alpha-Ag2WO4 microcrystals grow by aggregation and the Ostwald ripening process. PL properties of alpha-Ag2WO4 microcrystals decrease with an increase in the optical band-gap values (3.19-3.23 eV). Finally, we observed that large hexagonal rod-like alpha-Ag2WO4 microcrystals prepared by the SC method exhibited a major PL emission intensity relative to alpha-Ag2WO4 microcrystals prepared by the CP and CH methods. (AU)