Effect Of Ion Substitution On The Luminescence Properties Of BaCdP₂O₇:Eu²⁺ Phosphors

Phosphors play an important role in white LED.In order to develop new phosphors,experts and scholars put forward a lot of new strategies.One of the most important strategies is to regulate the lattice sites of phosphor matrix by ion substitution.So in this paper,based on the Ba Cd P₂O₇:Eu phosphor,the effects of ion substitution on the luminescence properties of Ba Cd P₂O₇:Eu phosphor were studied by replacing the cation and anion in the phosphor matrix.By adjusting the doping concentration ratio between ions,the effects of ion substitution on the structure of phosphors,the site occupation of Eu and the luminescent properties of phosphors were studied,which provided more theoretical basis for the lattice site control theory based on ion substitution and the spectral control of phosphors:（1）the Ba_0.97Cd_1-xZn_xP₂O₇:0.03Eu phosphors were prepared by replacing Cd²⁺with Zn²⁺at 900℃ in CO reduction atmosphere by high temperature solid phase method.The change of matrix structure and luminescence properties of phosphors after the substitution of Cd²⁺by Zn²⁺were studied.（2）the Ba_1-xZn_2-xP₂O₈:2xEu phosphors were prepared by replacing Cd²⁺with Zn²⁺at 900℃ in CO reduction atmosphere by high temperature solid phase method.The study of Ba_1-xZn_2-xP₂O₈:2xEu phosphors show that Eu ions mainly exist in the form of+3 valence in Ba_1-xZn_2-xP₂O₈:2xEu phosphors.When x≤0.03,with the increase of Eu doping concentration in Ba_1-xZn_2-xP₂O₈:2xEu phosphors,Eu³⁺preferently occupied the crystal lattice position of Zn,and Eu³⁺occupied the crystal lattice position of Zn²⁺was difficult to reduce to Eu²⁺.When x≥0.03,with the increase of Eu doping concentration,the number of Eu entering the position of Babegins to increase.However,Eu mainly occupies the crystal lattice position of Zn,so Ba_1-xZn_2-xP₂O₈:2xEu phosphors mainly show the red emission of Eu³⁺,and only a very small amount of Eu³⁺is reduced to Eu²⁺,so Eu²⁺emission is not strong.（3）the Ba_2-xZn_1-xP₂O₈:2xEu phosphors were prepared by replacing Cd²⁺with Zn²⁺at 900℃ in CO reduction atmosphere by high temperature solid phase method.However,a two-phase mixture（Ba₃（PO₄）₂and Ba Zn₂P₂O₈）of（BP+BZP）:2xEu phosphors were produced instead of the target product of Ba_2-xZn_1-xP₂O₈:2xEu.In（BP+BZP）:2xEu phosphor matrix,Eu exists in two valence states of+2 and+3 in phosphor.At 395 nm,Eu³⁺mainly shows electric dipole transition emission at 616 nm,suggesting that Eu³⁺mainly occupies the non-inversion center in（BP+BZP）:2xEu phosphors.By studying the luminescence properties of Eu²⁺in（BP+BZP）:2xEu phosphors,and comparing the excitation and emission spectra of Eu²⁺in（BP+BZP）:0.06Eu and Ba_0.97Zn_1.97P₂O₈:0.06Eu,it is preliminary proved that Eu²⁺does not mainly occupy the crystal lattice position of Ba in the lattice of Ba Zn₂P₂O₈,but the crystal lattice position of Ba in the lattice of Ba₃（PO₄）₂.These results in turn further prove that Eu mainly occupies the crystal lattice position of Zn²⁺in the lattice of Ba Zn₂P₂O₈.