Cluster Coordination and Photoluminescence Properties of α-Ag₂WO₄ Microcrystals

Abstract

In this paper, we report our initial research to obtain hexagonal rod-like elongated silver tungstate (α-Ag(2)WO(4)) 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 α-Ag(2)WO(4) 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 α-Ag(2)WO(4) 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 [WO(6)] clusters in the lattice, while EXAFS analyses confirmed that W atoms are coordinated by six O atoms. FE-SEM images suggest that the α-Ag(2)WO(4) microcrystals grow by aggregation and the Ostwald ripening process. PL properties of α-Ag(2)WO(4) microcrystals decrease with an increase in the optical band-gap values (3.19-3.23 eV). Finally, we observed that large hexagonal rod-like α-Ag(2)WO(4) microcrystals prepared by the SC method exhibited a major PL emission intensity relative to α-Ag(2)WO(4) microcrystals prepared by the CP and CH methods.

Elucidating the real-time Ag nanoparticle growth on α-Ag2WO4during electron beam irradiation: experimental evidence and theoretical insights

“…4165), and the strong diffraction peaks revealed crystallinity. The sample was totally monophased a-Ag 2 WO 4 , in good agreement with previous observations in neutral [63][64][65][66] or slightly alkaline 67 media. In a-Ag 2 WO 4 crystals, Ag ions can display different AgO x clusters corresponding to type-coordination and synergistic coordination modes in order to facilitate the formation of several clusters with low and high coordination numbers (x = 2, 4, 6 and 7).…”

Potentiated Electron Transference in α-Ag2WO4 Microcrystals with Ag Nanofilaments as Microbial Agent

“…However, X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses also confirm this structural feature. 57 Note that Raman analysis is incapable of detecting any significant change in both AWO and AWO:Ag samples. In contrast, results obtained from the FEG-SEM image and TEM analysis reveal a surface differentiation between the samples.…”

Effects of surface stability on the morphological transformation of metals and metal oxides as investigated by first-principles calculations

“…Among these, Ag 2 WO 4 has attracted considerable attention because of their potential applications in fields as ionic conductivity [134], photocatalysis [135], sensors [136], microbial agents [137], photoluminescence properties [137,138].…”