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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.)

Silver Molybdate and Silver Tungstate Nanocomposites with Enhanced Photoluminescence

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De Santana, Yuri V. B. [1] ; Cardoso Gomes, Jose Ernane [2] ; Matos, Leandro [2] ; Cruvinel, Guilherme Henrique [2] ; Perrin, Andre [3] ; Perrin, Christiane [3] ; Andres, Juan [4] ; Varela, Jose A. [2] ; Longo, Elson [1]
Total Authors: 9
[1] Univ Estadual Paulista, UNESP, CDMF INCTMN, Araraquara, SP - Brazil
[2] Univ Fed Sao Carlos, UFSCar, CDMF INCTMN, BR-13560 Sao Carlos, SP - Brazil
[3] Univ Rennes 1, Rennes - France
[4] Univ Jaume 1, Dept Expt Sci, Castellon de La Plana - Spain
Total Affiliations: 4
Document type: Journal article
Web of Science Citations: 43

Silver molybdate (Ag2MoO4) and silver tungstate (Ag2WO4) nanomaterials were prepared using two complementary methods, microwave assisted hydrothermal synthesis (MAH) (pH 7, 140 degrees C) and co-precipitation (pH 4, 70 degrees C), and were then used to prepare two core/shell composites, namely alpha-Ag2WO4/beta-Ag2MoO4 (MAH, pH 4, 140 degrees C) and beta-Ag2MoO4/beta-Ag2WO4 (co-precipitation, pH 4, 70 degrees C). The shape and size of the microcrystals were observed by field emission scanning electron microscopy (FE-SEM), different morphologies such as balls and nanorods. These powders were characterized by X-ray powder diffraction and UV-vis (diffuse reflectance and photoluminescence). X-ray diffraction patterns showed that the Ag2MoO4 samples obtained by the two methods were single-phased and belonged to the beta-Ag2MoO4 structure (spinel type). In contrast, the Ag2WO4 obtained in the two syntheses were structurally different: MAH exhibited the well-known tetrameric stable structure alpha-Ag2WO4, while co-precipitation afforded the metastable beta-Ag2WO4 allotrope, coexisting with a weak amount of the alpha-phase. The optical gap of beta-Ag2WO4 (3.3 eV) was evaluated for the first time. In contrast to beta-Ag2MoO4/beta-Ag2WO4, the alpha-Ag2WO4/beta-Ag2MoO4 exhibited strongly-enhanced photoluminescence in the low-energy band (650 nm), tentatively explained by the creation of a large density of local defects (distortions) at the core-shell interface, due to the presence of two different types of MOx polyhedra in the two structures. (AU)

FAPESP's process: 08/57872-1 - National Institute for Materials Science in Nanotechnology
Grantee:Elson Longo da Silva
Support type: Research Projects - Thematic Grants
FAPESP's process: 12/22823-6 - Nanocrystalline metal sulphides obtained by synthesis at the interface of two solvents assisted by microwave
Grantee:Yuri Vinicius Bruschi de Santana
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
Grantee:Elson Longo da Silva
Support type: Research Grants - Research, Innovation and Dissemination Centers - RIDC