Research On The Rare Earth Activating Phosphate,Borate Phosphor With Multi-Color Emission

LED is known as the 4^th lighting source in the 21^st century because of long lifetime,energy saving,environment friendly and high light quality.The white LEDs applied in the lighting fields are usually phosphor converted LEDs?pc-LED?;whose light comes from both LED chips and phosphors.The most common white LEDs on the maket are constructed with blue LED chip and yellow phosphor and its application is limited by the relatively low CRI?color rendering index?.The white light obtained by combining near ultraviolet?NUV?or ultraviolet?UV?LED and multi-color emitting phosphor?white light emitting phosphor or three primary colors emitting phosphor with single matrix?could reach CRI more than 95,hence the research on this kind of phosphors plays as a key role in the scientific and industrial communities.This paper aims to research white light emitting or three primary colors emitting phosphor which could be excited by NUV/UV light efficiently,and such developments have been achieved:1.Phosphor?-Ca₃(P_1-yV_yO₄)₂:xDy³⁺synthesized by high temperature solid state method calcined at 1100? had the pure whitlockite structure and doping with Dy³⁺ions and VO₄^3-didn't influence the crystal structure.Under 350 nm excitation,sample emitted bright white light;the intensity of hypersensitive transition ⁴F_9/2-⁶H_13/2 is weaker than ⁴F_9/2-⁶H_15/2,indicating that Dy³⁺ions tend to occupy sites with high point symmetry.The critical concentration of Dy³⁺was x=0.06 according to the quenching experiment;the concentration quenching mechanism was determined to be dipole-dipole interaction.The substitution of vanadate for phosphate group varied the yellow-to-blue ratio from 0.727 to 1.234,and the CIE color coordinates and correlated color temperature significantly varied from?0.274,0.338?to?0.320,0.385?and from 8670 to 5940 K,respectively.In another word,the substitution of VO₄^3-for PO₄^3-could realize variable white light emitted by Dy³⁺ions without changing the whitlockite structure that Dy³⁺ions doping in.This is significant for the Dy³⁺activating white light emitting phosphors applying in the solid state lighting field.2.Phosphor?-Ba₃Y?BO₃?₃:Ce³⁺,Tb³⁺,Eu³⁺synthesized by solid state method calcined at1100? had the pure layered structure of?-Ba₃Y?BO₃?₃ and the doption of rare earth ions didn't influence the crystal structure.The blue emission of Ce³⁺ions could be fitted with four Gauss distributions,indicating that Ce³⁺ions occupied two kinds of lattice sites.Tb³⁺ions could emit clear green light,but only can be excited by UVB radiation effectively.By co-doping Ce³⁺ions,the excitation range could be extended from 225³00 nm to 350 nm?UVA?,making the corresponding phosphor matching with UV LED.The red emission of Eu³⁺ions was dominated by transition ⁵D₀-⁷F₁ rather than the hypersensitive one ⁵D₀-⁷F₂,indicating that Eu³⁺ions should take Y sites with higher point symmetry.Of all phosphors in this serie,the CIE color coordinates of?-Ba₃Y?BO₃?₃:0.05Eu³⁺,?-Ba₃Y?BO₃?₃:0.01Ce³⁺,0.16Tb³⁺and?-Ba₃Y?BO₃?₃:0.01Ce³⁺were located at?0.615,0.368?,?0.256,0.480?and?0.154,0.052?in the red,green and blue zone,respectively,making these phosphors solid potential options for applications in NUV/UV LEDs.This work provided more options for phosphor in applications of LEDs.