Silver Molybdate and Silver Tungstate Nanocomposites with Enhanced Photoluminescence
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Otros documentos de la autoría: De Santana, Yuri V. B.; Cardoso Gomes, José Ernane; Matos, Leandro; Cruvinel, Guilherme Henrique; Perrin, André; Perrin, Christiane; Andres, Juan; Varela, José A.; Longo, Elson
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INVESTIGACIONMetadatos
Título
Silver Molybdate and Silver Tungstate Nanocomposites with Enhanced PhotoluminescenceAutoría
Fecha de publicación
2014Editor
InTechISSN
1847-9804; 1847-9804Cita bibliográfica
DE SANTANA, Yuri VB, et al. Silver Molybdate and Silver Tungstate Nanocomposites with Enhanced Photoluminescence. Nanomaterials and Nanotechnology, 2014, vol. 4, no. 22Tipo de documento
info:eu-repo/semantics/articleVersión de la editorial
http://www.intechopen.com/journals/nanomaterials_and_nanotechnology/silver-molyb ...Versión
info:eu-repo/semantics/publishedVersionPalabras clave / Materias
Resumen
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, ... [+]
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. [-]
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Nanomaterials and Nanotechnology, 2014, vol. 4, no. 22Derechos de acceso
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