A Single‐Phase Phosphor NaLa 9 (GeO 4 ) 6 O 2 : Tm 3+ , Dy 3+ for Near Ultraviolet‐White LED and Field‐Emission Display

Single‐phase white‐light‐emitting phosphors NaLa 9(1− x − y ) (GeO 4 ) 6 O 2 : x Tm 3+ , y Dy 3+ ( NLGO : x Tm 3+ , y Dy 3+ ) have been synthesized by a traditional solid‐state reaction method. The powder X‐ray diffraction ( XRD ), photoluminescence ( PL ), PL excitation ( PLE ) spectra, fluorescence decay curves, chromaticity coordinates, correlated color temperature ( CCT ), and the cathodoluminescence ( CL ) properties of the obtained phosphors are measured and discussed in detail. It is discovered that the series samples could be color‐tunable (from blue to yellow) by tuning the doping content of Dy 3+ with a fixed Tm 3+ content excited at 357 nm and white light (0.341, 0.324) could be obtained with the CCT of 5079 K. A NLGO : 0.01Tm 3+ , 0.02Dy 3+ is studied carefully as representative. The main emissions of Tm 3+ (453 nm, 1 D 2 – 3 F 4 ) and Dy 3+ (478 nm, 4 F 9/2 – 6 H 15/2; 572 nm, 4 F 9/2 – 6 H 13/2 ) make it emit white light with good thermal stability (67% of the initial till 523 K). The energy transfer from Tm 3+ to Dy 3+ is noticed and further research has been done to explain the enhancement of Dy 3+ emission and the excellent thermal stability. It also keeps stable under continuous electron bombardment with high intensity. All of these indicate that it could be a suitable candidate for white‐emitting phosphor applied for near ultraviolet‐white light‐emitting diode ( NUV ‐ WLED ) and field‐emission display (FED).