Study On Rare Earth/transition Metal Ion Doped Near Infrared Luminescent Materials

Near infrared luminescent materials have a wide range of applications in biomedicine,food detection,intelligent identification and other fields.Rare-earth doped near-infrared luminescence has the characteristics of strong biological tissue penetration,narrow emission spectrum and low background,and has important application prospects in biological analysis markers.Near-infrared luminescent materials doped with transition metal ions have the advantages of tunability and good thermal stability.In this paper,the luminescent properties of two kinds of near-infrared luminescent materials doped with rare earth ions and transition metal ions are studied respectively.（1）Sr₃Sn₂O₇:Nd³⁺series near-infrared phosphors were synthesized by high-temperature solid-state method,and it was determined that Sr_2.95Sn₂O₃:0.01Nd³⁺had the best luminescent performance,and its emission peak was at 1071 nm.The thermal stability of phosphor was studied,and it was found that its luminous intensity at 200℃could be maintained at 80%at room temperature.Furthermore,the sample was tested by stress luminescence,and it was found that it had good stress luminescence performance.The changes of photoluminescence and stress luminescence of phosphors doped with different proportions of boric acid and Sn/Si and Sn/Ge co-doping were studied.It is found that when 3mol%boric acid is added,the defect density of the matrix can be adjusted to enhance the stress luminescence.Similarly,when Sn/Si and Sn/Ge are co-doped,the crystal structure will be changed to control defects and enhance the stress luminescence characteristics of the materials.（2）The Li Ga₅O₈:x Ni²⁺near-infrared fluorescent material was prepared by high-temperature solid-state method,and the optimal doping concentration of Ni²⁺was 8%by optimizing the doping concentration of Ni²⁺.Compared with the standard card by XRD test,it is found that the diffraction peak of Ni²⁺ion moves towards the direction of low diffraction angle because the radius of Ni²⁺ion is larger than that of Ga³⁺ion.The excitation range of the material is 240-800 nm,which is distributed throughout the visible region.The emission spectrum is in the range of 1050-1600 nm,which belongs to typical broadband emission,and the position of emission peak is red-shifted with the increase of Ni²⁺concentration.The red shift is caused by the decrease of crystal field coefficient Dq/B due to the doping of Ni²⁺with larger radius.The luminescence mechanism and thermal stability were also studied.It is found that its luminous intensity at 140℃can be maintained at 78%of that at room temperature,which shows that it also has good thermal stability and has great application prospects in the field of lighting.