Synthesis, Characterization, Anisotropic Growth and Photoluminescence of BaWO4

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

This paper reports on the synthesis of barium tungstate (BaWO4) powders obtained by the coprecipitation method and processed in a domestic microwave-hydrothermal (MH) at 413 K for different times. These powders were analyzed by X-ray diffraction (XRD), Fourier transform Raman (FT-Raman) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and fieldemission gun scanning electron microscopy (FEG-SEM). XRD patterns showed that the BaWO4 powders present a scheelite-type tetragonal structure and free of secondary phases. FT-Raman spectra proved the evidence of a tetragonal structure due to W-O stretching vibration into the [WO4] tetrahedron groups. FT-IR spectra revealed a strong shoulder on the nu(3) bands in the transmittance spectra of the powders. FEG-SEM micrographs indicated that the powders present an octahedron-like morphology with agglomerated nature and polydisperse particle size distribution. The morphological evolution of BaWO4 powders with the processing time in a MH system was investigated and a possible growth mechanism was proposed. A green photoluminescence (PL) emission at room temperature was verified for the BaWO4 powders when exited by 488 nm wavelength. Finally, a model was proposed to explain this physical property.