Study On The Up-conversion Luminescence And Spectral Regulation Of Rare Earth Doped Tungstate

Rare earth doped up-conversion materials have been widely used in white light LED, bio-medical, color display. Tungstate is selected as host matrix and a series of rare earth doped tungstates have been synthesized through hydrothermal methods and sol-gel methods. The doping concentration, heat treatment impacted on up-conversion properties have beed studied. The doped transition metal and Nd3+ions impacted on emission spectrum have been investigated.NGW: Yb3+, Pr3+ nanocrystals have been synthesized through hydrothermal methods. The influence of different Pr3+ ion doping concentration impacted on up-conversion properties have been studied. The result shows that under the excitation with a 980 nm diode laser, several emission bands were found and the strongest is the red emission centered at 649 nm. It is found that optimal doping concentration of Pr3+ is 0.3%.Yb3+/Ho3+ co-doped Y6WO12 nanocrystals with different concentrations of Ho3+ions have been synthesized through a facile sol-gel method followed by a subsequent heat treatment. It is found that under the excitation of a 980 nm diode laser, the as-prepared nanocrystals show bright red and green luminescence. the emission intensity (red and green) increase with increasing Ho3+ concentration, maximizing at 1.0 mol%? With the elevation of the heat treatment temperature from 700 ? to 900 ?, the up-conversion emission intensity goes up significantly.Transition metal ions (Fe3+ and Cr3+ ions) co-doped NGW: Yb3+, Ho3+nanocrystals have been synthesized through a facile hydrothermal method and the doping concentration of transition metal ions impacted on emission spectrum have been investigated. The result shows that the prepared samples show bright red centered at 660 nm and green luminescence centered at 546 nm. It is found that optimal doping concentration of Fe3+ and Cr3+ ions are 30% and 10%, and the emission intensity is 9 and 3.1 times to the undoped samples, respectively.NGW nanocrystals co-coped with Yb3+, Ho3+ and Nd3+ ions (NGW: Yb3+,Ho3+,Nd3+) have been synthesized through hydrothermal method. The influence of Nd3+ ion doped concentration impacted on spectrum propertied have been studied. It is found that under the excitation of 980 nm laser, the samples show green (546 nm)and red emission (660 nm). With the increase of the concentration of Nd3+ ions,the relative intensity ratios of red to green light decrease gradually and the emission spectrum of the samples change from orange to yellow.