Photochromism And Luminescence Reversal Characteristics Of Rare Earth Modified Potassium-sodium Niobate Based Materials

With the development of science and technology,various electronic devices tend to function,miniaturization and intelligence.In recent years,people not only integrate and improve the original performance in the multi-functional materials,but also can develop and design the novel properties required.The multi-functional materials have been paid great attention to by the scientific community.At present,a variety of multi-functional material systems have been developed.In these materials systems,ferroelectric luminescent multi-functional materials are doped with rare earth to make ferroelectrics have luminescent properties on the basis of keeping ferroelectricity.Due to the prospect of optoelectronic devices,the ferroelectric luminescent multi-functional materials have the potential to be used in optoelectronic devices.Ferroelectric luminescent multi-functional materials have been paid more and more attention.?1-x?K_0.5Na_0.5NbO₃-xNa_0.5Er_0.5TiO₃ with perovskite structure were prepared by traditional solid-state sintering method at high temperature.Two kinds of upconversion luminescence?green at 530 nm and 551 nm,red at 660 nm?were observed by using 980nm laser as excitation source.Under the irradiation of sunlight or visible light??=407nm?,the ceramic samples had obvious photochromic phenomenon.The color of K_0.5Na_0.5NbO_3:xEr ceramic sheet changed from light yellow to black gray,and the color of the ceramic sample treated at 230?was restored to its original color.The photochromic phenomenon can be effectively read out by detecting the intensity change of the luminescence excitation spectrum.This luminescence-regulated contrast is as high as?R_t=74.21%.After multiple visible light excitation and heat stimulation,the luminescence intensity of the ceramics did not decrease obviously.These properties make KNN:xEr a potential photoelectric multifunctional material.K_0.5Na_0.5NbO₃ photochromic ceramics with different concentrations of Er/Yb were prepared by traditional solid-state sintering at high temperature.Using 980 nm laser as pump source,two color upconversion luminescence?557 nm green and 648 nm red?appeared.Under visible light irradiation??=407 nm?,the ceramic sample had obvious photochromic phenomenon.The photochromic phenomenon can be effectively read out by detecting the intensity of the luminescence emission,which has a contrast of up to?R_t=90.46%.Moreover,it can be used as a lossless high-density information storage device because it is non-destructive between the"write"and"read"of the information.In order to further explore the relationship between sintering temperature,luminescence controllable contrast degree??R_t?.On the basis of the previous group of experiments,a Er/Yb co-doped K_0.5Na_0.5NbO₃ sample was selected to sintering at different temperatures.The results show that the intensity of luminescence and the contrast of luminescence control are related to the degree of crystallization of the sample.The higher the sintering temperature is,the stronger the luminescent property and the ability of luminescence regulation can be obtained.(K_xNa_1-x)_0.997Pr_0.003:NbO₃ ceramics were prepared by traditional solid state sintering method at high temperature.By changing the proportion of K and Na and keeping the doping amount of Pr unchanged,the effect of volatilization of K and Na on the photochromism of KNN was determined.The effect of volatilization of Na on the luminescence regulation of KNN.The results show that the sintering temperature decreases with the decrease of Na content and the increase of K element.The contrast degree of luminescence regulation also increased from 7.3%to 59.31%of?R_t.The photochromic phenomenon of potassium sodium niobate is the interaction of K and Na elements.The ratio of K to Na is 7/3,which has the best effect of luminescence regulation.