Synthesis and characterization of a Eu³⁺‐activated Ba_2–xV₂O₇:xEu³⁺ phosphor using a hydrothermal method: a potential material for near‐UV‐WLED applications

Abstract

Eu 3+ -activated Ba 2 V 2 O 7 (Ba 2-x V 2 O 7 :xEu 3+ ) phosphor materials were synthesized using a hydrothermal method and different concentrations of europium (x = 0.01, 0.02, 0.03, 0.04, and 0.05%). Phase purity, structural, morphological, optical, and luminescence characteristics of the as-synthesized phosphors were studied using powder X-ray diffraction (XRD), high resolution scanning electron microscopy, UV-visible spectroscopy, and fluorescence spectrometry. The recorded XRD patterns of the as-synthesized phosphors were indexed and predicted to be a triclinic structure. A cube-like morphology was obtained for the as-prepared samples. Broad absorption in the UV region from 200 nm to 380 nm was observed and the good transparency in the visible region at 400-800 nm originated from the [VO 4 ] 3− group charge transfer (CT) transition. The broad emission peak centred at 499 nm was due to the CT band of the [VO 4 ] 3− group. Also, a sharp peak observed at 613 nm was due to the electric dipole transition of 5 D 0 ! 7 F 2 of Eu 3+ ions that occupied the lattice sites without inversion symmetry for all concentrations. The colour qualities of the as-prepared samples were calculated using Commission International de l'Eclairage coordinates. The colour-rending index (CRI) value was 86 for the Ba 1.97 V 2 O 7 :0.03Eu 3+ phosphor. Furthermore, a WLED with a high CRI value of 95 was achieved by coupling the 3 W 356 nm near-UV light-emitting diode (LED) chip with the Ba 2-x V 2 O 7 :xEu 3+ phosphor. These results suggested that the as-prepared phosphor materials are potential candidates for fabrication of near-UV chip excited WLEDs.

Synthesis and luminescence properties of Eu3+-activated Mg3(PO4)2 phosphors and substitution of phosphate with Molybdate, Tungstate and Sulphate

“…Interaction type is determined by θ value i.e. 3 (exchange interaction), 6 (dipole-dipole interaction), 8 (dipole-quadrupole interaction) and 10 (quadrupolequadrupole interaction) [21,22] .…”