Cluster Coordination and Photoluminescence Properties of alpha-Ag2WO4 Microcrystals

Autor(es)

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]

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: Inorganic Chemistry; v. 51, n. 20, p. 10675-10687, OCT 15 2012.
• Citações Web of Science: 97

Resumo

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)

• Processo FAPESP: 09/53189-8 - Propriedades fotoluminescentes e fotocataliticas dos tungstatos de ferro e manganes
• Beneficiário: Marcio Aurélio Pinheiro Almeida
• Modalidade de apoio: Bolsas no Brasil - Doutorado