Synthesis And Luminescence Properties Of Novel Boromphosphate And Phosphate Phosphors

A series of K1+xM1-2xCexBP2O8(M = Sr, Ba) and KBaBP2O8:Eu3+ phosphors with different x value were prepared by a conventional high-temperature solid-state reaction method. The phase purity, surface morphology, compositional and elemental analysis as well as photoluminescence properties were investigated by various characterization methods including X-ray diffraction(XRD), scanning electron microscopic(SEM), energy dispersive X-ray spectra(EDS),fourier transform infrared(FT-IR), and fluorescence spectroscopy(FS) measurements, respectively. The luminescence characteristics including excitation and emission spectrum, decay curves, chromaticity coordinates and color purity were discussed and calculated. The results showed that K1+xM1-2xCexBP2O8(M = Sr, Ba) can be effectively excited by short-wavelength ultraviolet(<320 nm), and exhibit long-wavelength ultraviolet(320 nm- 400 nm) emission corresponding to the 5d-4f transitions of Ce3+. The spectroscopic characteristics of Ce3+ which include Stokes shift and crystal field depression were investigated and compared with that in other borophosphates. The influence of the doping concentration on the relative emission intensity of Ce3+ was investigated and the critical distance Rc was estimated in term of the concentration quenching data. The as-prepared phosphor KBaBP2O8:Eu3+ can be effectively excited with a 394 nm light, and exhibit orange emission with high color purity belonging to the prevailing 5D0?7F1 magnetic dipole transition(594 nm) of Eu3+. The influence of the doping concentration of Eu3+ and charge compensator(alkali metal ion) on the relative emission intensity of Eu3+ was investigated. The above work indicates this phosphor could be a potential candidate as orange phosphor for application in white light-emitting diodes(w-LEDs).The UV-Vis spectroscopic properties of the samples of ?-Zn3(1-x)Mn3xBPO7 and ?-Zn3BPO7:Ln(Ln = Ce3+,Eu2+,Eu3+) were investigated. The excitation spectrum of ?-Zn3(1-x)Mn3xBPO7 phosphors consists of a broad excitation band peaking at 255 nm and a group of line-shaped excitation peaks around 350 nm and 500 nm, which can be attributed to the charge transfer transition in Mn2+–O2- bonds and the inner d–d electron transitions of Mn2+ ion, respectively. The emission bands are due to 4T1(4G) ? 6A1(6S) transition of the Mn2+ ion and there exists efficient energy transfer from charge transfer state of Mn2+–O2- bonds to Mn2+ ions. The dependence of emission wavelength on Mn2+ concentration is studied. The decay curve of Mn2+ ions luminescence in ?-Zn3BPO7:Mn2+ is also measured. The f–d transitions of Ce3+ and Eu2+ ions in ?-Zn3BPO7 are assigned and corroborated, which lead to the broad emission band in ultraviolet(UV) and visible region for Ce3+ and Eu2+ Ions under UV excitation, respectively. Typical reddish orange emission from Eu3+ in the host lattice was also observed. The spectroscopic characteristics including Stokes shift, crystal field depression, electron–vibrational interaction, and charge transfer band were investigated and compared with that in other borophosphate phosphors. ?-Zn3BPO7:Eu2+ and ?-Zn3BPO7:Eu3+ phosphors show potential application in solid state lighting region.The luminescence properties of Sm3+ doped ?-Sr2P2O7 phosphors without and with co-doping different charge compensation agents such as Li+, Na+, K+ and Cs+ were studied. The excitation and emission spectrum, decay curves, and the effect of charge compensation agents on the luminescence properties of ?-Sr2P2O7:Sm3+ were investigated in detail. The results demonstrate that the as-prepared ?-Sr2P2O7:Sm3+ phosphors can be efficiently excited by ultraviolet light, and the emission spectrum consists of three emission peaks at 561, 601, 642 nm. By introducing the charge compensator M+(M+ = Li+, Na+, K+ and Cs+) into the ?-Sr2P2O7:Sm3+ phosphor, the emission intensity can be enhanced remarkably.Two series of phosphors ?-Sr2(1-x)Dy2xP2O7 and ?-Sr2(1-2x)Dy2x Li2xP2O7 with different x values were synthesized successfully by using a conventional solid state method at high temperature for the first time, and their luminescence properties were investigated comparatively. The effect of Li+ ion on the luminescence properties of Dy3+ in ?-Sr2P2O7 host including luminescence intensity, optimal doping concentration, concentration quenching mechanism, decay behavior, and etc was discussed in detail by considering the defect generation in ?-Sr2P2O7:Dy3+, the charge compensation of Li+ ion and the role of Li2CO3 as solid flux expected in phosphors. The obtained excitation and emission spectra indicate these as-prepared phosphors can be excited by ultraviolet, and show white light emission due to the combination of the 4F9/2?6H15/2 and 4F9/2?6H13/2 transitions of Dy3+ ion. The CIE chromaticity coordinates and color correlated temperature of Dy3+ emission in the phosphor ?-Sr2(1-2x)Dy2xLi2xP2O7(x = 0.03) with the optimal fluorescence intensity was also calculated. The present work could be helpful to understand the effect of the charge compensator(e.g. Li+ ion) on the luminescent properties of phosphors with non-equivalent ion-displacement and design novel phosphors by efficiently taking advantage of charge compensator(e.g. Li+ ion).