Effect of different surfactants on the shape, growth and photoluminescence behavior of MnWO4 crystals synthesized by the microwave-hydrothermal method

Autor(es)

Almeida, M. A. P. ^[1] ; Cavalcante, L. S. ^[2] ; Varela, J. A. ^[2] ; Siu Li, M. ^[3] ; Longo, E. ^{[2, 1]}

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Carlos, INCTMN DQ, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Estadual Paulista, INCTMN, BR-14801907 Araraquara, SP - Brazil

^[3] Univ Sao Paulo, IFSC, BR-13560970 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ADVANCED POWDER TECHNOLOGY; v. 23, n. 1, p. 124-128, JAN 2012.
• Citações Web of Science: 26

Resumo

In this communication, we report the effect of different surfactants {[}cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and sodium bis(2-ethylhexyl)sulfosuccinate (AOT)] on the shape, growth and photoluminescence (PL) behavior of manganese tungstate (MnWO4) crystals synthesized by the microwave-hydrothermal (MH) method at 413 K for 45 min. These crystals were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), ultraviolet-visible (UV-vis) absorption spectroscopy and PL measurements. XRD patterns proved that these crystals have a monoclinic structure. FE-SEM images showed that MnWO4 crystals exhibit different shapes and growth mechanisms depending on the surfactant employed. The CTAB cationic surfactant promotes the hindrance of small nuclei that leads to the formation of flake-like nanocrystals, while SDS and AOT anionic surfactants promote a growth of crystals to plate-like and leaf-like crystals due to considerable size effect of counter-ions (RSO4- and RSO2O-) and an increase in Na+ ion remnants. UV-vis absorption spectroscopy revealed different optical band gap values due to modifications in the shape, surface and crystal size. Finally, the effect of surfactants on the crystal shapes and average crystal size distribution causing changes in the PL behavior of MnWO4 crystals was explained. (C) 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. (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