Study On The Preparation And Luminescence Properties Of Rare Earth Tantalum Phosphate Phosphors For White Light LEDs

The phosphors with rare earth ions as activation ions and phosphates and tantalates as matrix have the characteristics of stable physical-chemical properties,high luminous efficiency and radiation resistance,which have important application value in the field of white light emitting diode(LED)lighting.In this paper,the common substrate of phosphate and tantalate was designed,and the synthesis structures and luminescence performances of Y(Ta1-xPx)O4:y at.%Eu3+and Gd(Ta1-xPx)O4:y at.%Tb3+co-substrates synthesis were studied in detail,specific as follows:(1)A series of UV-activated phosphors Y(Ta1-xPx)O4:y at.%Eu3+were synthesized by high temperature solid-state method.It is found that PO43-can enter into YTaO4 crystal structure with a maximum doping concentration of 1%.And the luminescence performances of Y(Ta1-xPx)O4:Eu3+can be continuously improved with the increase of PO43-doping.Gauss fitting analysis demonstrates that the excitation bands of Y(Ta1-xPx)O4:Eu3+are mainly composed of charge transfer bands of TaO43-(peak center is located in 230 nm)and Eu3+(peak center is located in 250 nm)which indicates that TaO43-has energy transfer effect on Eu3+615 nm emission.The characteristic emissions of Eu3+excited by 250 nm ultraviolet light occurred at 595 nm and 615 nm,corresponding to the energy level transitions of 5D0?7F1 and 5D0?7F2,respectively.It is of particular note that the color coordinates of Y(Ta0.99P0.01)O4:Eu3+in the yellow-red region can be modulated by changing the doping concentrations of Eu3+.And the optimum doping concentration of Eu3+with the strongest luminous intensity and the highest color purity is 7 at.%.The fluorescence lifetime of the Y(Ta0.99P0.01)O4:7 at.%Eu3+phosphors is 1.19 ms.The experimental results show that Y(Ta0.99P0.01)O4:Eu3+phosphors can be used as solid-state luminescent phosphors with adjustable light color.(2)A series of Gd(Ta1-xPx)O4:y at.%Tb3+phosphors with various doping concentrations of PO43-and Tb3+were prepared through high temperature solid-state method.Under the condition of 1300 ?,the single-phase M-GdTaO4 was successfully prepared without phase change.The experimental results show that PO43-ions can be successfully doped into the crystal structure of Gd(Tal-xPx)O4,and the maximal doping concentration was 20%.As the PO43-ion doping concentration increases,Gd(Ta1-xPx)O4:5 at.%Tb3+phosphor luminescence performance gradually strengthen untail doping concentration is 10%.And the influence of proportion change on its structure and luminescence property was discussed in detail.The excitation spectrum of Gd(Ta1-xPx)O4:Tb3+phosphors mainly consists of two parts:the excitation band of TaO43-(the excitation peak center is located at 235 nm)and the excitation band of Tb3+(the excitation peak center is located at 255 nm),which proves the existence of energy transfer between TaO43-and Tb3+ions.Gd(Ta0.9P0.1)O4:Tb3+phosphors have the maximum luminous intensity when the doping concentration of Tb3+ions is 10%.The fluorescence attenuation of Tb3+ion in Gd(Ta0.9P0.1)O4 phosphor substrate was in line with the single exponential attenuation trend,and the fitting fluorescence lifetime of Tb3+ion was 1 ms.And CIE chromaticity results imply the phosphors exhibit yellowish-green emission.These results suggest the Gd(Ta0.9P0.1)O4:y at.%Tb3+phosphors are promising candidates for LED luminescence or medical imaging applications.