The structural and luminescence properties of divalent europium ion-doped barium borophosphate

Abstract

A series of BaBPO5 phosphor samples doped with different concentration of Eu2+ ions, up to 0.6 mol % were synthesized by solid state reaction method. The mixtures of (NH4)2HPO4, BaCO3, H3BO3 and Eu2O3were heated in pure argon atmosphere at 850°C where the reduction of Eu3+ to Eu2+ ions occurred. The structural properties of the phosphors were analyzed by X-ray diffraction technique (XRD) and Fourier transform infrared spectroscopy (FTIR). The morphology of the phosphors was investigated by scanning electron microscope (SEM). The luminescence properties of the phosphors were observed at room temperature using photoluminescence (PL) spectrometer where the effects of Eu2+ ions in the phosphors were investigated. The XRD results show that, all the doped and undoped samples are polycrystalline with hexagonal host structure. The SEM images of the samples show particles of BaBPO5 were agglomerated with irregular morphology and no significant difference were found between the doped and the undoped samples. The particles have an average size of about 0.1 – 1 μm. The similarity in the morphology suggests that the Eu2+ ions do not cause any changes to the host structure. The PL results show that the undoped sample does not have distinct luminescence characteristic while the samples doped with Eu2+ ions have broad emission band in violet region of 350 – 420 nm centered at 383 nm which is attributable to transition of configuration state 4f6 5d1  4f7 of the Eu2+ ions. The emission intensity is affected by the concentration of Eu2+ where optimum intensity was observed for 0.2 mol % of Eu2+ ions. The FTIR spectra show that the samples are dominated by tetrahedral group of BO4 and PO4 to form a 3-dimensional network. The occurrence of emission lines in violet region indicates that this phosphor has potential for application in solid-state lighting.