Cluster Coordination and Photoluminescence Properties of α-Ag2WO4 Microcrystals

被引：174
作者：
Cavalcante, L. S. [1 ,3 ]
Almeida, M. A. P. [2 ]
Avansi, W., Jr. [1 ]
Tranquilin, R. L. [2 ]
Longo, E. [1 ,2 ]
Batista, N. C. [3 ]
Mastelaro, V. R. [4 ]
Siu Li, M. [4 ]
机构：
[1] Univ Estadual Paulista, BR-14801907 Sao Paulo, Brazil
[2] Univ Fed Sao Carlos, BR-13565905 Sao Paulo, Brazil
[3] UESPI CCN, Dept Quim, BR-64002150 Teresina, PI, Brazil
[4] Univ Sao Paulo, IFSC, BR-13560970 Sao Paulo, Brazil
来源：
INORGANIC CHEMISTRY | 2012年 / 51卷 / 20期
基金：
巴西圣保罗研究基金会;
关键词：
AG-AT-AGCL; PHOTOCATALYTIC PROPERTIES; SILVER TUNGSTATE; STRUCTURAL REFINEMENT; STABLE PHOTOCATALYST; HIGHLY EFFICIENT; GROWTH-PROCESS; CRYSTAL; MICROWAVE; MECHANISM;
D O I：
10.1021/ic300948n
中图分类号：
O61 [无机化学];
学科分类号：
070301 ; 081704 ;
摘要：
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.
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收藏
页码：10675 / 10687
页数：13
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