Synthesis and luminescent properties of Na5La1−xEux(WO4)4 red phosphors

A series of Na5La1−xEux(WO4)4 (x=0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1.0) phosphors have been synthesized successfully by a solid-state reaction technique and characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Rietveld refinement. The photoluminescent properties have also been systematically investigated under the near-ultraviolet light. High concentration of doped Eu3+ enhanced the UV absorption and consequently red emission without concentration quenching. The Na5Eu(WO4)4 phosphor was observed a strong red emission under 395 nm excitation, bearing with 47% quantum efficiency and the CIE chromaticity coordinates (x=0.67, y=0.33) being close to the National Television Standard Committee (NTSC) standard values. The primary studies indicate that Na5Eu(WO4)4 is a promising candidate as the red phosphor for white light-emitting diodes (LEDs).