Synthesis And Luminescence Properties Of A Single-phased Ca₆BaP₄O₁₇ Phosphor For UV-pumped White LEDs

In recent years,more attention has been paid to White light emitting diode?WLED?as a new generation of luminescent lighting,which has become a hot spot in international lighting research.White LEDs are admired for their apparent advantage in longevity,energy conservation,environmental protection,rapid response speed and low working voltage.It is universal for blue chip coated YAG phosphors?yttrium zirconium garnet?yellow phosphor to generate white light-emitting diodes in current commercial production.Such simple method make lower cost and high production efficiency,which is practical in large.However,there are some problems in process.It is difficult to control the quality in the glue mixing,which may cause poor color rendering and poor stability.In response to this problem,the researchers have also proposed the way of single-phased full-color emitting phosphor upon UV-LED chip.This method can achieve extremely high color reduction index,and the stability of color light depends only on phosphor.Proper phosphor make white lights stable.Hence,it is worth studying for the good thermal stability and high color rendering full-spectrum phosphors based on single substrate.In this paper,we prepared the Ca₆BaP₄O₁₇:Ce³⁺,Eu²⁺,Sm³⁺ phosphors forUV excitation by high temperature solid phase method.Details are as follows:?1?Prepare the Ca₆BaP₄O₁₇:Sm³⁺ phosphor samples,the XRD?X-ray diffraction?analysis were checked of phosphor powder.Phosphor can be motivated by 406 nm UV effectively and emit the strong red light.The emission spectrum measured of Ca₆BaP₄O₁₇:Sm³⁺ phosphor,the intensity reach the at maximum 603 nm?4G5/2-6H7/2?,another emission peak observed 565 nm?4G5/2-6H5/2?,658nm?G5/2-6H9/2?and 710 nm?4G5/2-6H11/2?,respectively.Ca₆BaP₄O₁₇ co-doped Ce³⁺-Sm³⁺ phosphors were synthesized successfully,under the 380 nm irradiation,the recorded emission spectrum reveal that the peak at 490 nm,belong to the transition 5d-4f of Ce³⁺ ions.Of course,we can found the characteristic peak of Sm³⁺.The color-tunable can realize by changing the doping concentration of the rare earth ions.The energy transfer phenomenon between Ce³⁺ the Sm³⁺ rely on the electric dipole-dipole interaction between energy transfer can be explain by calculation results.?2?The Ca₆BaP₄O₁₇:Eu²⁺ phosphors were synthesized successfully,meanwhile,we found that the best temperature in the preparation of the phosphor is 1250?,we got the yellow phosphor by sintering 10 hours under1250?.The excitation spectrum of the sample is a range from 400 nm to 475 nm and the emission spectra at 545 nm has an obvious broad band emission as the transition of the outer electrons(Eu²⁺)from the 5d excited states to 4f ground state.The phosphor can be effectively stimulated by ultraviolet light thus used in the preparation of white light phosphor power.Addition,we also obtain theCa₆BaP₄O₁₇:Ce³⁺,Eu²⁺ phosphor,under the excited of 380 nm ultraviolet light,the characteristic peak of Ce³⁺ ion and Eu²⁺ ions can be detected.With the increasing concentration of the Ce³⁺,the color presented of the sample changing from yellow to blue and green region.The calculating results indicated that the energy transfer occur between Ce³⁺ and Eu²⁺.?3?Synthesized the Ca₆BaP₄O₁₇:Ce³⁺,Eu²⁺,Sm³⁺ phosphors,under the excitation of 380 nm UV light,the measurement of the emission spectrum presents the peak at 490 nm and 545 nm correspond to the transition 5d-4f of Ce³⁺ and Sm³⁺,respectively,the band peak of Sm³⁺ also be found in the spectrum.As the three doped ions can emit the different light of own,we can try to adjust the amounts of three kinds of rare earth doped ions to obtain the white light with the ideal value of color coordinates?0.342,0.301?,and achieve a scientific purpose which the white phosphor of full spectrum.