Luminescence Modulation Properties And Multifunctional Applications Of Rare-earth Orthoniobate Photochromic Materials

The optical storage has the advantages of large capacity,longer life and high resolution.Rare earth doped inorganic photochromic materials are considered to be an essential part of high-density optical data storage materials due to their good thermal stability,good fatigue resistance and low cost.However,there are still many challenges in the practical application of today’s inorganic photochromic materials for optical storage.For example,some inorganic compounds have the disadvantage of single-color emission,lower luminescence modulation contrast,and non-destructive readout,etc.These problems are more or less hindering the progress of inorganic photochromic materials.The fabricated novel rare earth orthoniobate photochromics（RNb O₄,where R=Yb,Er,Tm or Ho）with self-activated upconversion emissions exhibit reversible coloring-bleaching processes upon light stimuli（365 and 405 nm）.And the secondary absorption to an excitation energy of 980 nm can be effectively avoided.A non-destructive luminescence readout can be realized while maintaining a near 100%luminescent switching contrast（99.2%）.It provides new insights for future high-performance inorganic photochromic materials and promotes their practical application in advanced optical storage.A series of fergusonite structure Er³⁺/Tm³⁺/Yb³⁺tri-doped YNb O₄ photochromic ceramics were designed with multicolor upconversion modulation.The multi-band modulations of vis-NIR emission exhibit perfect reversibility upon light stimuli（365 nm and405 nm）.When x=0.15,the luminescence color of the sample changed from yellow to red after the photochromic reaction under the excitation of 980 nm laser(ΔR_green=86.21%,ΔR_red=82.12%,respectively).The thermometric properties of thermally coupled energy levels and non-thermally coupled energy levels of the samples based on photochromic reaction were systematically investigated.The temperature measurement characteristics of thermal coupling energy level and non-thermal coupling energy level of the sample are studied.The maximum Sa value of thermal coupling energy level is 0.45×10^-2 K^-1,and the maximum Sr value is 1.17%K^-1.The maximum Sa value of the No-thermal coupling energy level is 7.25×10^-2 K^-1,and the maximum Sr value is 4.1%K^-1.Finally,Eu³⁺ion was introduced into the YNb O₄ photochromic host in order to obtain efficient emission.The results show that YNb O₄:Eu³⁺ceramics can be effectively excited by 395 nm ultraviolet light,resulting in efficient and stable red emission.The influence of different irradiation wavelengths on the photochromic reaction of the samples was investigated,and it was found that the luminescence switching contrast of the samples reached a maximum at 320 nm.In addition,the unique ferroelastic domain structure inhibits the recombination probability of photo-generated electron-hole pairs,and the analysis of spherical aberration electron microscope provides atomic scale structural evidence for photochromic reaction.The writing,erasing,and reading strategies for flexible films and square ceramic are particularly suitable for complex application environments in optical storage and rewritable flexible devices.