Synthesis of scheelite-type materials by microwave-assisted hydrothermal and its luminescence and photocatalytic properties

• Ano de defesa: 2021
• Autor(a) principal: Morais, Artur de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Rio Grande do Norte; Brasil; UFRN; PROGRAMA DE PÓS-GRADUAÇÃO EM CIÊNCIA E ENGENHARIA DE MATERIAIS
• Palavras-chave em Português: Scheelite; Hydrothermal; Photoluminescence; Photocatalysis
• Link de acesso: https://repositorio.ufrn.br/handle/123456789/44788

Scheelites are widely researched materials due to their excellent properties and applications in light emission technologies, in addition to good chemical and thermal stability. Combining functional materials with efficient and clean synthesis techniques is becoming increasingly necessary in our world. In this work, Scheelites CaMoO4, CaWO4 and CaWO4 doped with 1% europium were obtained using the microwave-assisted hydrothermal method for 1, 2, 4 and 8 minutes and their photoluminescent and photocatalytic properties in the degradation of methyl orange and rhodamine B dyes were evaluated. Individual material formulations were developed for the composite emission to become white. The compounds were characterized by x-ray diffraction (XRD), photoluminescence (PL), UV-Vis spectroscopy and scanning electron microscopy (FESEM). The XRD results show that the samples are pure, without secondary phase precipitation, showing that the europium is introduced in the structure. The results of UVVis show that the energy band gaps are within the range commonly reported in the literature. The micrographs show well-defined morphologies and help in the discussion about the growth process of the particles. Photoluminescence shows emissions in the blue, green and pink regions for CaWO4, CaMoO4 and CaWO4:Eu, respectively. Europium emissions are very visible and dominate the red region in the PL spectrum. The formulations developed showed emissions very close to the white region of the spectrum. The photocatalytic activity showed that the formulations were not efficient in the degradation of methyl orange, removing only 20% of the dye after 120 minutes under UV light irradiation. However, they proved to be very efficient in removing rhodamine, reaching values close to 75% of dye removal.