Rietveld refinement, cluster modelling, growth mechanism and photoluminescence properties of CaWO4:Eu3+microcrystals

• DOI: 10.1039/c4ce02279c
• Publication Date: 2015-01-07T09:00:58Z
• Authors: R. F. Gonçalves; L. S. Cavalcante; I. C. Nogueira; E. Longo; M. J. Godinho; J. C. Sczancoski; V. R. Mastelaro; I. M. Pinatti; I. L. V. Rosa; A. P. A. Marques
• Keywords: Rietveld Refinement; XANES; Tetragonal crystal system

CaWO4:Eu3+ microcrystals (with 0, 1, 2 and 4 mol% Eu3+) were synthesized by a co-precipitation (CP) method grown in microwave-assisted hydrothermal (MAH) system at 130 °C for 30 min. X-ray diffraction (XRD), Rietveld refinement, absorption near edge spectroscopy (XANES), Fourier-transform Raman (FT-Raman) infrared (FT-IR) indicated that all of the have scheelite-type tetragonal structure without deleterious phases. Structural refinement data employed to model [CaO8], [EuO8] [WO4] clusters. XANES spectra confirmed presence deltahedral clusters promotes small distortions neighbouring tetrahedral global lattice. Field emission scanning electron microcopy (FE-SEM) images revealed replacement Ca2+ Eu3+ ions changed particles' shapes, resulting different morphologies microcrystals. UV-vis diffuse reflectance reduction optical band gap with ions. The photoluminescence (PL) properties CaWO4 studied as well chromaticity coordinates lifetimes these compounds.