Submicro-crystals of BaWO4:Eu3+ and BaMoO4:Eu3+ synthetized by Pechini Method

Abstract

In the scheelite-related red phosphors, molybdate and tungstate are respectable high-quality host material. The central metal ions, Mo6+ and W6+, are coordinated to four oxygen atoms in tetrahedral symmetry (Td). Then, molybdate and tungstate demonstrate be chemically stable, red-emitting phosphors, very suitable for in lightening and bio-application.[1] Additionally, molybdate and tungstate phosphors have broad absorption bands owing to charge transfer (CT) from oxygen to metal in the near-UV region. Scheelite BaMoO4 and BaWO4 have almost ideal structure of the MO4 2− and display excellent thermal and hydrolytic stability [2-3]. Rare Earth Molybdates and Tungstate x%Eu:(BaMO4)3 submicron materials with smart photoluminescent properties were prepared using Pechini method. The powders were characterized by XRD, infrared absorption spectroscopy, thermal analyses, Scanning Electronic Microscopy and a criterions study of PL properties. These rare earth doped materials present highly intense red (Eu3+), luminescence under UV radiation. The structure change with the concentration of dopand, in this case concentration of Eu3+. The excitation spectra of these compounds presented broad bands arising from ligand–to–metal charge transfer (O→Mo6+, O→W6+ and O→Eu3+) and narrow bands related to 4f–4f intraconfigurational transitions. The emission spectra exhibited the 5D0→7FJ (J= 1–4) transitions, for the systems doped with Eu3+, while a broad band assigned to the LMCT (O→Mo;W) are observed when the excitation is monitored on the O→Mo;W LMCT state around 286 nm