Preparation and properties of Eu3+ doped tungstate red phosphor powders

Abstract

NaY(WO4)2:Eu3+ phosphors were synthesized using high-temperature solid state method. The effects of Eu3+ doping concentrations on structure and photoluminescence properties of the powders were investigated. The results indicate that the pure NaY(WO4)2:Eu3+ phase can be produced by calcining at 800°C where Eu3+ doping does not alter the main phase structure. Eu3+ ions were successfully incorporated into the crystal lattice, replacing Y3+ at the B-site. This caused gradual shifts of the characteristic X-ray diffraction peaks to lower 2θ angles. Morphological characterization revealed that the sample particles had irregular polygonal shapes with sizes ranging from 100 to 300 nm. There was minimal variation in morphology among samples with different doping concentrations. The samples exhibited the characteristic spectral emission of Eu3+ and emitted red light at a wavelength of 616 nm when excited by 394 nm near-ultraviolet light. The luminescence intensity of the nanophosphor gradually increased with increasing Eu3+ doping concentration, reaching its maximum at a doping ratio of 0.6, followed by a decrease due to the concentration quenching. The quenching mechanism was analysed to be primarily dipole-dipole interaction, in accordance with the Dexter’s theory of doping concentration. The luminescence positions of the phosphors slightly changed with varying Eu3+ doping concentrations, and the colour coordinates closely matched the standard value of the red colour in the National Television Standards Committee, confirming the stability of the obtained powders as red phosphors.

Keywords

• tungstate
• eu-doping
• solid state synthesis method
• photoluminescence
• quenching mechanism