Fabrication And Research Of Red Phosphor Used For White LED

In this paper, some kinds of red phosphor of Alkaline phosphate used for near ultraviolet LED (White LED) were fabricated by traditional high temperate solid stated method. The crystal structures were analyzed by XRD (X-ray diffraction). The emission and excitation spectra were measured. The luminescence properties and appearances of samples were researched. The chief contents are given as follows:(1) A red-emitting phosphor BaZn2(PO4)2:Eu3+ was prepared by high temperature solid-state reaction. The excitation and emission spectra of BaZn2(PO4)2:Eu3+phosphors were measured. The results showed that the main excitation peaks were located at 360-400nm and the emission peaks were at 595nm. The effect of Eu3+ concentration on the emission spectrum intensity of BaZn2(PO4)2:Eu3+ was investigated, and the results showed that the emission spectrum intensity increased with increasing Eu3+ concentration, and reached the maximum value at 3% Eu3+, then decreased. Under the condition of doping 3% Eu3+, the effects of charge-compensating on the emission intensity were also investigated. Under the conditions of charge compensation Cl-, Li+, Na+, or K+ incorporated in BaZn2(PO4)2, the luminescence intensities of BaZn2(PO4)2:Eu3+phosphor were enhanced.(2) The BaZn2(PO4)2:Sm3+ red phosphor was synthesized by high temperature solid state reaction and its luminescence properties were studied. The emission spectrum consists of three major orange-red emission bands. The emission peaks are located at 569 nm,607nm and 661nm corresponding to the 4G5/2â†'6H5/2,4G5/2â†'6H7/2,and 4G5/2â†'6H9/2 typical transition of Sm3+ respectively and the strongest one appears at 607 nm. Its excitation spectrum extends from 260nm to 460nm which indicates that this phosphor can be excited effectively by near-ultraviolet light-emitting diode (UVLED).(3) A red-emitting phosphor CaZn2(PO4)2:Eu3+ was prepared by high temperature solid-state reaction. The excitation and emission spectra of CaZn2(PO4)2:Eu3+ phosphors were measured. The results showed that the main excitation peaks were located at 350-410nm and the emission bands peaking at 585nm and595nm (5Do～7F1),615nm,622nm and 629nm (5D0～7F2),656nm (5D0～7F3) and 688nm (5D0～7F4), which are corresponded to the typical transition of Eu3+. The effect of Eu3+ concentration on the emission spectrum intensity of CaZn2(PO4)2:Eu3+ was investigated, and the results showed that the emission spectrum intensity increased with increasing Eu3+ concentration, and reached the maximum value at 10% Eu3+, then decreased. Under the condition of doping 10% Eu3+, the effects of charge-compensating on the emission intensity were also investigated. Under the conditions of charge compensation Li+, Na+, or K+incorporated in CaZn2(PO4)2, the luminescence intensities of CaZn2(PO4)2:Eu3+phosphor were enhanced.(4) Phosphors of Sr3Y(PO4)3:Eu3+ were synthesized by high temperature solid state reaction. Luminescent properties were studied. The strongest excitation spectrum is at 399nm. So Sr3Y(PO4)3:Eu3+ red-emitting phosphor is suitable for white light emitting diode(w-LED) based on UV InGaN chip. The emission bands peaking at 592nm and598nm (5D0～7F1) 617nm,622nm and 630nm (5D0～7F2),654nm (5D0～7F3) and 690nm (5D0～7F4), which are corresponded to the typical transition of Eu3+. The influence of the concentration of Eu3+ ions to the emission intensity was investigated and the concentration quench was not happened but have the quench trend. It was also found that the Bi3+ in the system can increase the emission intensity of Sr3Y(PO4)3:Eu3+. The energy transfer from Bi3+ to Eu3+ in the paper was also discussed.