Study On Mechanoluminescence Properties Of Pr³⁺ Doped NaNbO₃·LiNbO₃ Heterojunction-structured Materials

Mechanoluminescence is a kind of light emission triggered by mechanical action.Due to unique energy conversion from mechanical energy to optical energy,mechanoluminescent materials have great potential in the field like in-situ crack detection,multi-mode anti-counterfeiting mode,motion analysis,energy acquisition and utilization,thus have received increasing attention of researchers in recent years.So far,although researchers have discovered mechanoluminescent materials from near ultraviolet to visible and even near infrared light-emitting and have made pleasant progress in the field like color hybridization and crack detection,but most of mechanoluminescent materials have not stepped into practice because of its weak luminescence.Therefore,it is of great importance to explore the enhancement mechanism behind the mechanoluminescence and realize the enhancement of the mechanoluminescence properties of materials.Two kinds of easily-prepared red mechanoluminescence materials Na Nb O₃:Pr³⁺and Li Nb O₃:Pr³⁺were selected to change the sintering temperature under the fixed doping concentration of Pr³⁺.The influence of sintering temperature on the crystal phase,photoluminescence properties and mechanoluminescence properties of the product were systematically studied.The defect properties of materials with different sintering temperatures were studied by thermoluminescence.After the preparation and characterization of the series of materials,the controlled preparation of the mechanoluminescence materials was achieved.Subsequently,the mechanoluminescence performance of Na Nb O₃:Pr³⁺was significantly improved by combining the flux agent way and heterojunction structure way.The mechanoluminescence performance of the sample under different pressures was studied and its potential application in crack detection and pressure sensing was demonstrated.XRD was used to study the crystal phase evolution trend of the series samples.TEM and SEM were applied to analyze the microstructure evolution of the samples.The differences and variation trends of mechanoluminescence and photoluminescence were compared,and the possible reasons for mechanoluminescence enhancement were revealed by thermoluminescence test.Finally,to understand mechanoluminescence enhancement mechanism deeply,We applied piezoresponse force microscopy to analysis the piezoelectricity of materials,positron annihilation lifetime to study the internal defect evolution of materials,the first principle to calculate the heterojunction band structure of sample and normal sample.According to the test and calculation results,Possible explanations for mechanoluminescent performance improvement were suggested.Our study provides theoretical guidance and experimental reference value for the design of high performance mechanoluminescence materials in the future.