Study Of Up/down Conversion Luminescence Properties Of ABSi₂O₈（A=Na,Ba;B=Zn,Al）Phosphors Doped With Rare Earth Ions Er³⁺,Tb³⁺,Yb³⁺

For luminescent materials,high luminescence efficiency and good luminescence thermal stability are very important.In recent years,a new type of non-contact temperature sensor（optical temperature sensor）has attracted attention due to its wide application in special environments such as toxic and high temperature.In addition,with the development of science and society,the demand for energy saving and environmental protection has started to rise.Therefore,in this paper,phosphors that can improve the sensitivity and luminescence efficiency and luminescence thermal stability of non-contact temperature sensors are prepared,and their luminescence performance,luminescence mechanism and their applications are investigated in detail.（1）Li⁺,K⁺ion-doped Na₂Zn₃Si₂O₈:Er³⁺novel phosphors were synthesized by high-temperature solid-phase method.The analysis revealed that the phosphor is homogeneous and contains two main characteristic emission bands of Er³⁺ions in the visible region,green and red,at 980 nm excitation,and the doping of Li⁺and K⁺ions increased the luminescence intensity of Na₂Zn₃Si₂O₈:Er³⁺phosphor at 661 nm by 36 and 21 times,respectively.Fourier transform spectroscopy（FT-IR）plots of the samples showed that the doping of Na₂Zn₃Si₂O₈:Er³⁺phosphor with Li⁺,K⁺ions resulted in a significant reduction of the absorption peaks,further confirming the increase of the luminescence intensity.the doping of Li⁺,K⁺ions changed the optical temperature measurement parameters of Na₂Zn₃Si₂O₈:Er³⁺phosphor,i.e.,the maximum relative sensitivity reached 19.69%K^-1and the highest absolute sensitivity of 1.20%K^-1are better than most studies reported on the up-conversion temperature sensing characteristics activated by Er³⁺ions.The phosphor monochromatic analysis showed an orange-red luminescence of the sample,which is consistent with the emission spectral results.Therefore,Li⁺,K⁺ion-doped Na₂Zn₃Si₂O₈:Er³⁺orange-red phosphors are expected to have potential applications in the fields of optical temperature sensors and solid-state lighting.（2）Ba Al₂Si₂O₈:Tb³⁺,Yb³⁺green phosphors were successfully prepared by high-temperature solid-phase method,and the introduction of Tb³⁺and Yb³⁺ions did not affect the crystal structure of Ba Al₂Si₂O₈.The samples showed strong green emission under both UV（377 nm）and NIR（980 nm）excitation,demonstrating the existence of both down-conversion and up-conversion emission processes.The energy transfer tendency between Tb³⁺and Yb³⁺ions was investigated,and it was found that the highest energy transfer efficiency(η_ET)of Tb³⁺→Yb³⁺reached 62.8%and the highest quantum shearing efficiency(η_QE)was as high as 162.8%.By analyzing the variation of up-conversion emission intensity at different excitation pumping powers,it was found that the main realization of up-conversion emission in this series of phosphors are all two-photon processes.the plots of variable temperature emission spectra and the variation of activation energy with temperature for Ba Al₂Si₂O₈:Tb³⁺,Yb³⁺phosphors in the range of25-300℃indicate that the phosphors have excellent luminescence thermal stability and can convert part of the infrared light into visible light.Therefore,Ba Al₂Si₂O₈:Tb³⁺,Yb³⁺phosphor is an efficient new green phosphor and is expected to have potential applications in solid-state lighting and biomarkers.