Preparation And Near-infrared Luminescence Properties Of La₂MgGeO₆:Yb And La₂MgGeO₆:Er System Fluorescent Materials

Light-emitting materials play an important role in human life,from early painting to modern times.They are widely used in various fields,such as lighting,electronic display devices,detection,diagnosis and so on,while near-infrared light-emitting materials can be applied to solar cells,material analysis,infrared camouflage,fluorescent labeling and other aspects.In recent years,the application of near-infrared luminescent materials doped with lanthanide rare earth has been increasing,which has attracted more and more attention from researchers.In this work,a new photoluminescent near infrared double perovskite ceramic material La₂MgGeO₆:Yb was prepared by high temperature solid phase method.X-ray powder diffraction（XRD）,ZEISS Sigma 300 field emission scanning electron microscope（SEM）,dual beam ultraviolet visible spectrophotometer（TU-1901）and Edinburgh steady state/transient fluorescence spectrometer（FLS1000）were used to characterize the structure and luminescence properties of the samples.It is found that the double perovskite-type luminescent ceramic material La₂MgGeO₆:Yb can emit900-1100 nm near-infrared light under the excitation of ultraviolet light source at 287 nm,and its central wavelength is 1014 nm.At the sintering temperature of 1450℃,change the Yb content La_2-xMgGeO₆:x Yb（0.001≤x≤1）,double perovskite type light-emitting ceramic material La₂MgGeO₆:Yb samples can emit near-infrared light with a central wavelength of 1014 nm.When x≤0.05,the near-infrared fluorescence luminescence intensity increases with the increase of Yb content.When the Yb content is 0.05,the near-infrared fluorescence luminescence effect is the best.And then the near-infrared fluorescence intensity decreased with the increase of Yb content.In addition,when the Yb content is 0.05,changing the sintering temperature of double perovskite type luminescent ceramic material La_1.95MgGeO₆:0.05Yb,the luminescent intensity increases first and then decreases with the temperature,reaching the maximum value at 1450℃.The results of fluorescence performance test show that the luminescent performance is ranked from high to low:1450℃>1500℃>1400℃>1550℃>1350℃.Through a series of experiments,it is found that 1450℃ double perovskite luminescence ceramic La_1.95MgGeO₆:0.05Yb has the best near-infrared luminescence effect,and the fluorescence intensity is much higher than other near-infrared luminescence materials Zn₂Sn O₄:Cr and MgGeO₃:Pr.At the same time,XRD and SEM results show that with the increase of sintering temperature,the crystal cell grows gradually,the lattice distortion decreases gradually,and the crystal growth is more close to perfection.The optimal temperature for crystal growth is 1450℃,which is the same as optimal luminescence performance（1450℃）.Under the action of the surrounding crystal field,electronic can transition from one sub-level of the ²F_5/2 energy level of Yb³⁺to four sub-levels of the²F_7/2 energy level.The wavelength of the near-infrared light emitted by the transition matches well with the near-infrared light emitted by the double perovskite type luminescence ceramic material La_1.95MgGeO₆:0.05Yb sintered at 1450℃.A new photoluminescent double perovskite ceramic material La₂MgGeO₆:Er was prepared by high temperature solid phase method.X-ray powder diffraction（XRD）,ZEISS Sigma 300 field emission scanning electron microscope（SEM）and Edinburgh steady state/transient fluorescence spectrometer（FLS1000）were used to characterize the structure and luminescence properties of the samples,the luminescent ceramics emit visible and near infrared light under excitation of ultraviolet light wavelength of 379 nm,the five very obvious emission peaks in the emission spectrum are 525 nm,543 nm,851 nm,988 nm and 1529 nm,among which the fluorescence emission intensity of the two peaks of 988 nm and 1529 nm is much higher than that of the other emission peaks,and the wavelength with the strongest fluorescence emission intensity is 988 nm.At the sintering temperature of 1450℃,changing the Er content La_2-xMgGeO₆:x Er（0.01≤x≤0.2）,the samples can emit five obvious emission peaks of 525 nm,543 nm,851 nm,988nm and 1529 nm.The fluorescence intensity of the samples first increases and then decreases with the Er content,and the fluorescence luminescence effect is the best when the Er content is 0.05.In addition,when the Er content is 0.05,changing the sintering temperature of La_1.95MgGeO₆:0.05Er,the fluorescence luminescence intensity increases first and then decreases with the temperature,reaching the maximum value at 1450℃,and the luminescence performance is ranked from high to low as follows:1450℃>1500℃>1400℃>1550℃>1350℃.Through a series of experiments,it is found that the double perovskite type luminometric ceramic material La_1.95MgGeO₆:0.05Er at 1450℃ has the best near-infrared luminescence,and its fluorescence intensity is much higher than other near-infrared luminometric materials La_1.95MgGeO₆:0.05Yb,Zn₂Sn O₄:Cr and MgGeO₃:Pr.The results of this experiment are not only of great significance to the research of dual-perovskite luminescent ceramics La₂MgGeO₆:Yb and La₂MgGeO₆:Er near-infrared luminescent ceramics,but also promote the development of near-infrared luminescent ceramics.