Achievement Of Color-adjustable Borate Phosphor And Its Property Based On Energy Transfer And Host Composition

A series of M₃Tb（BO₃）₃:Ln³⁺(M=Sr and Ba,Ln=Sm³⁺and Eu³⁺),Ca₂BO₃Cl:Eu²⁺,nM²⁺（M=Sr and Ba）and Ca₂（BO₃）_1-x（PO₄）_xCl:Eu²⁺phosphors were synthesized.The microstructure,X-ray diffraction,luminenscent properties,energy transfer,chromaticity coordinates and theremal properties of the phosphors were studied.（1）A series of new tunable emission phosphors of Sm³⁺and Eu³⁺single-doped M₃Tb（BO₃）₃（M=Sr and Ba）phosphors were synthesized by the solid-state reaction.crystallization behavior and structure,reflectance spectral properties,luminescence properties,energy transfer,lifetimes,temperature dependent luminescence properties and CIE chromaticity coordinate of M₃Tb（BO₃）₃:Ln³⁺（M=Sr and Ba,Ln=Sm and Eu）were systematically investigated.M₃Tb（BO₃）₃（M=Sr and Ba）crystallizes in a rhombohedral cell with space group R-3 by Rietveld structure refinement of the obtained phosphors with the standard data of Ba₃Dy（BO₃）₃.Sr₃Tb（BO₃）₃ and Ba₃Tb（BO₃）₃ emit yellowish-green emission with the main peak around 555 nm and 550 nm,respectively,which originates from ⁵D₄→⁷F₄ transition of Tb³⁺,and M₃Tb（BO₃）₃:Ln³⁺（Ln=Sm and Eu）phosphors show intense yellowish-green,yellow,orange and red emission with increasing Ln³⁺concentration under274 nm and 286nm excitation.The orange-red/red emissions peaked at 613nm(Sr₃Tb（BO₃）₃:Sm³⁺),627nm(Sr₃Tb（BO₃）₃:Eu³⁺),607nm(Ba₃Tb（BO₃）₃:Sm³⁺)and 625nm(Ba₃Tb（BO₃）₃:Eu³⁺)are contributed to the efficiently energy transfer Tb³⁺→Sm³⁺and Tb³⁺→Eu³⁺.（2）Single-phased and single Eu²⁺doped warm white-light phosphors Ca₂BO₃Cl:Eu²⁺,nM²⁺（M=Sr and Ba）were synthesized by controlling cations substitution systematically.The XRD,luminenscence properties and CIE chromaticity coordinate of Ca₂BO₃Cl:Eu²⁺,nM²⁺（M=Sr and Ba）phosphors were anylysized.Warm white light can be clearly generated by combining the blue emission（⁴10nm）and the yellow emission（577nm）.In our case,for warm white phosphors CBL:Eu²⁺,0.07Sr²⁺and CBL:Eu²⁺,0.01 Ba²⁺,the corresponding color coordinates（x,y）is（0.3890,0.3538）and（0.3602,0.3171）,CCT is 3647K and 3980K,and meanwhile Ra value is 64 and 80,separately.Therefore,a wider spectral distribution of blue and yellow emissions for CBL:Eu²⁺,M²⁺（M=Sr and Ba,）is sufficiently applied in high-quality white-lighting source for indoor lighting.The use of cations to replace the cations in the host to achieve a blue-yellow dual-emission single-doped phosphor is an effective method for the preparation of solid-state light sources.（3）High luminous efficacy,high-color-rendering index（CRI）,single-phased and single Eu²⁺doped warm white-light phosphors Ca₂（BO₃）_1-x（PO₄）_xCl were synthesized by controlling anion substitution systematically.The anionic polyhedron substitution of PO₄ for BO₃ causes a great distortion of the host lattice,which enables the tuning of luminescent properties.An additional distinct emission peaking at 462 nm(in addition to 577nm of Ca₂BO₃Cl:Eu²⁺)was observed under the same excitation when PO₄^3-was introduced.Therefore,with the crystal structure evolution,the ratio blue/yellow was changed by adjusting the ratio of BO₃/PO₄,which provides a new way for developing a high CRI warm white-light phosphor.The internal quantum efficiency（IQE）of the Ca₂（BO₃）_0.64（PO₄）_0.36Cl:Eu²⁺phosphor was 64.0%.Thewarmwhitelight-emittingdiode（w-LED）wasfabricatedwith Ca₂（BO₃）_0.64（PO₄）_0.36Cl:Eu²⁺phosphor and a 380 nm-emitting InGaN chip,which exhibited promising properties,such as the high Ra（83.4）,the low correlated color temperature（3907K）and high luminous efficacy?_L（30.4 lm/W）.Importantly,the w-LED shows a greater R9=39.3versus R9=14.3 of commercial YAG:Ce³⁺.As a warm white phosphor for Ca₂（BO₃）_1-x（PO₄）_xCl:Eu²⁺has a broad application prospect in indoor lighting.