Study Of Borophosphate Phosphors Based On LED Illumination Applications

Light Emitting Diodes(LEDs)possess the advantages of long life,small size,easy transportation,low energy consumption and can be used in a variety of service environments.Therefore,LEDs arouse much attention of the researchers.At present,the commercial light-emitting diode devices are produced using LED chips and phosphors.In this work,we prepared a series of Tm³⁺,Eu³⁺/²⁺,Cu²⁺,Ce³⁺,Dy³⁺,Bi³⁺,Sm³⁺,Pr³⁺ions doped borophosphate phosphors by high temperature solid state reaction method.The relationships among the luminescent properties,the structures and compositions of the as-obtained phosphors were investigated.We studied a series of Sr₃(PO₄)_2-x(BO₃)_x:Tm,Eu(0?x?0.6)phosphors.With the increase of boron content in the sample,the content of crystal Sr₃(PO₄)₂ decreased.On the contrary,the content of crystal Sr₅(PO₄)₃(OH)increased,which changes the crystal environment in which Tm/Eu ions are located,and affects the electronic transitions of Tm/Eu ions.Thus the luminescence behaviors of the phosphors are controlled accordingly.In addition,the sintering atmosphere also has a certain influence on the luminescence performance of the phosphors.The phosphors Sr₃(PO₄)_2-x(BO₃)_x:Tm,Eu(0?x?0.6)have potential application prospects in light-emitting diodes.Cu²⁺and Sm³⁺doped Ca₃(BO₃)_n(PO₄)_2-n(0?n?2)phosphors were investigated.The effect of the substitution of phosphorus(P)with boron(B)on the structure and luminescence properties of phosphors is mainly concerned.It is found that the introduction of boron can change the structure and luminescent properties of phosphors.Three crystal phases Ca₃(BO₃)₂,Ca₃(PO₄)₂ and Ca₅(PO₄)₃OH were produced by the substitution of phosphorus(P)with boron(B).The luminescent properties of phosphors can be well adjusted by changing the excitation wavelength.The as-prepared phosphors can be used as a kind of potential light conversion material for white light emitting diodes.Cerium(Ce),dysprosium(Dy)doped three different substrates(Ca₃(BO₃)_0.6(PO₄)_1.4,Sr₃(BO₃)_0.6(PO₄)_1.4,(Ca_0.5Sr_0.5)₃(BO₃)_0.6(PO₄)_1.4)phosphors were studied.Ce/Dy doped different substrate phosphors display the difference in the excitation and emission spectra,which is reflected in the different intensity of the spectra and the position of the emission peaks.Based on the XRD patterns,we find that the matrix Ca₃(BO₃)_0.6(PO₄)_1.4 has two crystalline phases i.e.,Ca₃(PO₄)and Ca₅(PO₄)₃(OH).The other two substrates are pure single phases.The three substrates have different crystal environments.The electronic transition and energy transfer of Ce and Dy were impacted,which is responsible for the difference in the spectra of cerium and dysprosium ions in the three substrates.In addition,by adjusting the excitation wavelength,the luminescence performance of Ce/Dy doped(Ca_1-xSr_x)₃(BO₃)_0.6(PO₄)_1.4 phosphors can also be effectively adjusted.With Sr₃(BO₃)_0.4(PO₄)_1.6 as the matrix,doped with bismuth ions(Bi³⁺)and different contents of praseodymium ions(Pr³⁺),we examined the influence of different excitation wavelengths and bismuth ions on the spectra of praseodymium ions.After analyzing the fluorescence spectra,it is found that in the phosphor samples,the optimal doping amount of Pr³⁺ion is 0.02,and different excitation wavelengths can effectively change the position and intensity of the emission peak of Pr³⁺ions.The introduction of Bi³⁺ions also affect the electronic transition of Pr³⁺ions,resulting in a difference between the emission spectra of the bismuth/praseodymium co-doped phosphor and the praseodymium single-doped phosphor.The luminescent colors of the phosphors can be tailored by adjusting the content of Bi³⁺/Pr³⁺,so we can achieve the blue emission and orange emission,which is significant in practical applications.