Study On The Preparation And Properties Of Borate/Phosphate Phosphors

As a potential solid state lighting source for general illumination,light emitting diode?LED?has the advantages of long life,small size and low energy consumption,and is considered to be one of the most promising lighting sources.Herein,a series of borate/phosphate phosphors which can be used in LED were prepared by high temperature solid state method.The structure,morphology and luminescence behavior of the as-prepared phosphors were investigated by the X-ray diffraction?XRD?,infrared and Raman spectra,scanning electron microscope?SEM?,emission and excitation spectra,color coordinate and correlated color temperature.We mainly explored the effect of phosphor matrix composition,structure,type and concentration of the doped ions on the luminescence properties of the phosphors.The mechanism to modify the luminescence performance of phosphors was examined.The electronic transitions and energy transfer of the doped ions was also studied.The borate/phosphate phosphors with superior performances were obtained for LED applications.A series of Eu²⁺and Mn²⁺singly or doubly doped Ca₁₀Na?PO₄?₇?CNPO?phosphors were synthesized.Under the excitation of ultraviolet?UV?light,the Eu²⁺-singly activated CNPO phosphors exhibit two intense and broad emission bands,and the relative emission intensity of these two emission bands depends on the variation of excitation wavelength and Eu²⁺content.Co-doping Eu²⁺and Mn²⁺is an effective approach to enhance the red emission of Mn²⁺.The energy transfer of Eu²⁺to Mn²⁺is responsible for the enhanced Mn²⁺luminescence.The tunable emissions of the Eu/Mn codoped CNPO phosphors are achieved via energy transfer process and changing the content of Mn²⁺.We also studied the Bi³⁺/Sm³⁺/Dy³⁺doped Ca₃?BO₃?₂ phosphors.The luminescence from Bi³⁺in the phosphors can be observed.The local environment surrounding the doped ions may be changed with the increase of Sm³⁺/Dy³⁺content,leading to the variation of the luminescence of the phosphors.A series of Ce³⁺/Dy³⁺doped Ca₃(P_1-xB_xO₄)₂ phosphors were investigated.It is found that crystal transformation from?-Ca₃?PO₄?₂ to Ca₅?PO₄?₃?OH?occurred in the phosphors with the variation of boron content,which can provide various local environments for the doped rare earth ions and affect the emission behavior of Ce³⁺.For Ce³⁺/Dy³⁺co-doped phosphors,the luminescence intensity of Ca_2.93(P_1-xB_xO₄)₂:0.01 Ce³⁺,0.06 Dy³⁺phosphor is changed with the increase of boron content,and the emission peak of Ce³⁺appeared redshift.The results showed that the luminescence properties of the phosphors could be tailored effectively by varying the concentrations of the B³⁺ions as well as the excitation wavelengths.The developed phosphor has great potential as a single component white-light-emitting phosphor for white light emitting diodes.