Research On The Discoloration Effect Of Molybdenum Trioxide And Its Application

Among the chromic materials,inorganic color chromic materials have been the research focus in recent years due to their excellent reversibility,fatigue resistance,and stability.Mo O3 has excellent discoloration properties such as thermochromic and photochromic,although these excellent properties have attracted widespread attention and research of scientific researchers,but because of its huge application potential,new application areas are constantly increasing.In this work,the research focuses on the thermochromic and photochromic properties of molybdenum trioxide.Based on the explanation of its discoloration mechanism,the rare earth doping is used to modulate the color change to control the rare earth doped up-conversion luminescence.In addition,the fingerprint collection was realized by multi-band discoloration outside the band gap.MoO₃ ceramics were also prepared by the solid-phase method.The samples were irradiated with lasers?473nm,532nm,808nm,and 980nm?in different wavelength bands outside the band gap.The sample color turned blue.After the heat treatment,the sample color returned to the original state.The degree of discoloration of the sample can be modulated by controlling the power density and irradiation time of the laser.The study was conducted by applying a thermal stimulus alone,and it was found that the sample was also capable of discoloring,so the discoloration was attributed to light-induced thermal discoloration.This discoloration process also has excellent reversibility,repeatability and recyclability.Based on light-induced thermochromic discoloration,after a finger presses on the surface of the MoO₃ ceramic and leaves sweat-latent fingerprints,the sample is illuminated with laser light in different wavelength bands to make blue fingerprints appear,and fingerprint collection is achieved.The fingerprint collected by this method has high sharpness and good contrast.It can be collected repeatedly in reversible cycles and the fingerprint coloring effect is not weakened.The fingerprint pattern is still clear and stable after being placed for 360 days.It is a new type of fingerprint collection method,and it also broadens the application field of color changing materials.In addition,MoO₃:Yb³⁺,Er³⁺phosphors were prepared by solid-phase method in 500?in air atmosphere for 2h.The phosphors were sintered again in a reducing atmosphere,the color of the sample turned blue,and then the samples were sintered again in the air atmosphere,the color of samples turned back to the original color,so thermochromic was achieved.This thermochromic phenomenon is caused by the sintering of the sample in a reducing atmosphere to generate low-value Mo⁵⁺and oxygen vacancies,while the element valence and oxygen vacancies return to the original state when the colored sample sintered in the air atmosphere.The original sample emits green light under 980nm laser irradiation,while in the blue sample,the luminescence disappears;and when the color returns,the luminescence of the sample also recovers.Therefore,by controlling the color of the sample,the up-conversion luminescence can be regulated,and the regulation has reversible,cyclic and gradient controllability.