Effect Of Y³⁺ On The Luminescence Properties Of Eu²⁺ Doped KSrPO₄ And NaSrPO₄ Phosphors

The chemical formula ABPO₄ alkali-alkaline earth phosphate has high stability and excellent physical and chemical properties.Eu²⁺doped alkali-alkaline earth phosphate can efficiently absorb the ultraviolet light of 200-400 nm and emit bright blue light.It is a high-quality matrix material for phosphor.In order to obtain white light from a single matrix,many attempts have been made in Eu²⁺doped ABPO₄ alkali-alkaline earth phosphate,such as changing the crystal field environment of Eu²⁺,but the spectral movement is limited and the position of color coordinates cannot be effectively changed.Instead,Mn²⁺ion is added to achieve light conversion through energy transfer.Also because the efficiency is too low,the red light emission intensity is too low to be utilized.In this paper,Y³⁺is used as the doping ion to achieve spectral regulation in Eu²⁺-doped alkaline-alkaline earth phosphate KSr PO₄ and Na Sr PO₄ blue phosphors,and the mechanism of spectral changes is analyzed.The specific content is as follows:（1）KSrPO₄:Eu²⁺,Y³⁺phosphors were successfully prepared at different temperatures.Under 360 nm excitation,KSr PO₄:Eu²⁺exhibits a broad emission band with maximum at 425nm due to the 4f⁶5d¹→4f⁷ transition of Eu²⁺ions.The samples co-doped with Y³⁺ions reveal the presence of additional broad emission band with a peak at about 525 nm,whose relative intensity gets enhanced with the increase of Y³⁺content and synthesis temperature.The new emission was assigned to originate from defects related to introduction of Y³⁺ions that causes charge mismatch and lattice distortion.（2）On the basis of the above,KSr PO₄:Eu²⁺,Y³⁺,Mn²⁺phosphors were successfully prepared under CO reduction atmosphere.It is found that the red emission intensity of Mn²⁺is significantly enhanced when Y³⁺is doped into KSr PO₄:Eu²⁺,Mn²⁺phosphors.Through the fluorescence lifetime decay test,it is found that the lifetime decay of defect luminescence center is very fast,which indicates that the improvement of Mn²⁺red emission intensity is due to the energy transfer from defect luminescence center to Mn²⁺luminescence center.（3）NaSrPO₄:Eu²⁺,Y³⁺phosphors were successfully prepared by high-temperature solid-state reaction.Under 360 nm excitation,the Na Sr PO₄:Eu²⁺phosphor only showed an asymmetric broadband peak at 445 nm,because of the Eu²⁺occupying different Sr²⁺sites.Then discussed the best doping concentration of Eu²⁺,and analyzed the reason of concentration quenching was thedipole-quadrupole interaction.When Y³⁺ions enter the lattice system,the emission spectrum of the sample has an obviously broadened.By analyzing the spectrum and fluorescence lifetime,the doping of Y³⁺causes multiple emission of Eu²⁺occupying different Sr²⁺positions and defect emission.