Synthesis and luminescence properties of intensely red-emitting Na₅Y(WO₄)₄:Eu³⁺ phosphor

The luminescence and chromaticity characteristics of Na₅Y(WO₄)₄: Eu³⁺, a type of red-emitting phosphors, are examined. To make Na₅Y(WO₄)₄: Eu³⁺ phosphor, a conventional solid-state reaction technique has been employed. The photoluminescence emission(PL) and photoluminescence excitation(PLE) spectra indicate that the absorption of light is mostly due to W → O charge transfer at 319 nm wavelength and Eu³⁺ transitions are obtained in the near-UV and visible areas, whereas red emissions are due to intra-configurational 4f-4f Eu³⁺ transitions. The CIE chromaticity coordinates for Na₅Y(WO₄)₄: Eu³⁺ are (0.68, 0.31), which is the same as the commodity phosphor Y₂O₂S:Eu³⁺. Characteristic line emission is seen, with the strongest emission at 619 nm. The intensity of the luminescence is constrained by Eu³⁺ concentration due to energy transfer. Furthermore, Na₅Y(WO₄)₄: Eu³⁺ phosphors are interesting prospects for w-LEDs.