LiNb(Ta)O₃:Pr³⁺ Different Shape Materials Luminescence Performance Optimization And Applied Research In Stress Detection

With the continuous development of industrial technology,the stress-strain detection of various metal composite materials with excellent performance has been brought to our attention.At present,the main stress-strain detection methods are electrical measurement method,mechanical measurement method and optical measurement method.The mechano luminescence and force-induced photoluminescence in the photometric method,as two new types of stress-strain detection methods,can be applied to the stress-strain detection.Compared with mechanoluminescence,force-induced photo luminescence has the advantages of good detection continuity and high sensitivity.In addition,the luminous intensity changes significantly when force is applied.This performance change can be combined with optical testing equipment,which can be more accurately and timely reflect the changes in the internal stress of the material structure.However,there are still some problems,on the one hand,different forms have different effects on its luminescence performance,and on the other hand,the photoluminescence mechanism under force-induced is not clear.Besides,most of the current luminescent materials used for stress-strain detection are not stable and prone to deliquescent denaturation,as well as do not conform to the concept of green environmental protection.These shortcomings also greatly limit the development of this material in the field of stress-strain detection.The ABO3 perovskite material has the advantages of good thermal stability and low preparation cost,and been doped with rare earth ions,it has excellent optical and electrical properties,so it can be used as a luminescent material with excellent performance.In this paper,the luminescent material prepared by Pr³⁺ doped ABO3-type perovskite was selected to study the influence of different forms on its luminescence performance,and the mechanism of photo luminescence under force-induced was described.Meanwhile,the stress-strain detection performance of the traditional SrAl2O4:Eu²⁺ material was compared.The main findings are as follows:(1)Srl₂O₄:Eu²⁺,LiNbO3:Pr³⁺,and NaNbO3:Pr³⁺,these kinds of phosphors were prepared by high-temperature solid-phase method.Firstly,the influence of different doping amounts of Eu²⁺and Pr³⁺ on the luminescence performance was investigated,and the optimal Eu²⁺ doping concentration was 2%mol;the optimal doping amount of Pr³⁺ in LiNbO3:Pr³⁺ was 1%mol;the optimal doping amount of Pr³⁺ in NaNbO3:Pr³⁺was 0.8%mol.Secondly,LiNbO3:Pr³⁺ doped alkali metal Na+ improved its excitation intensity and luminescence performance at 460nm.Under the condition that LiNbO3:Pr³⁺ is a single phase,the optimal doping amount of Na+is 5%mol,and the luminous intensity is the highest.Finally,comparing the spectral change trends of Li1-xNaxNbO3:Pr³⁺ and SrAl2O4:Eu²⁺ under force-induced,the stress response threshold of SrAl2O4:Eu²⁺ is about 5000N,while the stress response threshold of LiNbO3:Pr³⁺ is 2000N.After doping with 5%mol Na+,the luminescence intensity under force induction is lower than that of LiNbO3:Pr³⁺.As the stress continues to increase,the luminous intensity increases,but the sudden increase disappears.(2)By adding different sintering aids(Bi₂O₃;Y2O3;Y2O3:Eu²⁺),Li1-xNaxNbO3:Pr³⁺ ceramic sheets were prepared by high temperature solid phase method.After the ceramic chip was prepared,the luminescence performance has been improved to a certain extent,but the excitation wavelength at 355nm of the ceramic chip without sintering aid showed a linear downward trend.We measured the piezoelectric coefficient(d33)of the Li1-xNaxNbO3:Pr³⁺ ceramic without adding sintering aids,and found that its downward trend was consistent with the downward trend of 355nm,and by preparing a comparison sample,the elements were qualitatively and quantitatively analyzed,Studied the change of this phenomenon in depth,and attributed it to the doping ions Na+occupying the lattice position of Li+,which increased the structural asymmetry around Pr³⁺ in the Li1-xNaxNbO3:Pr³⁺ matrix.(3)The O₃:Pr³⁺ red phosphor was prepared by high-temperature solid-phase method.The PL intensity reached a maximum at Pr³⁺=0.8%mol.Then,the addition of sintering aids improved the porcelain-forming properties of O₃:Pr³⁺,and which also enhanced its excitation intensity at 303nm and 460nm.Finally,the effects of both of Y2O3 and Bi₂O₃ sintering aids,as well as sintering aids doped with activators(Y2O3 and Y2O3:Eu³⁺)on the ceramic properties and luminescence properties of ceramic sheets were compared.The optimal addition amount of Bi₂O₃ was obtained,and compared with O₃:Pr³⁺ phosphor,the ceramic sheets of luminous intensity was increased by 7.4 times.Meanwhile,when stress was applied to O₃:Pr³⁺ ceramic sheets,the change of luminous intensity was detected,and eliminates its stress threshold.