Study On The Preparation And Properties Of Yb,Tm,Er Doped Gd₂O₃ Powder By Co-precipitation Method

Luminescent materials are widely used in daily life,such as lighting?energy-saving lamp?,display?LED,CRT TV,LCD TV,PDP?,DVD,diagnosis?X-ray and tomographic scanning?or laser device and material manufacturing.Rare earth ion doped oxide phosphor is a kind of low-cost,environment-friendly and multi-functional material.It can be synthesized by many different methods and can produce different colors of luminescence in a wide range of visible light fields.Phosphor powders based on oxide upconversion and downconversion can be used in solid-state lighting and solar cells.Therefore,the preparation of doped oxide materials with stable luminescence and high purity has become a hot topic for researchers.In this thesis,Gd₂O_3:Yb,Tm,Er phosphors were prepared by coprecipitation method.The calcination temperature,the pH value of solution and the concentration of doped rare earth ions were controlled by comparing different precipitators?aqua ammonia and ammonium bicarbonate?.The influence of these factors on crystal structure,morphology and luminescent properties of the Phosphor powders was discussed.Through XRD,TG-DSC,SEM,FTIR and PL characterization tests of the prepared samples and the author's analysis,the following conclusions have been reached:Gd₂O_3:Yb,Tm,Er phosphors were prepared by coprecipitation method,which can form crystalline phase when calcined at 600?.The best preparation process of Gd₂O_3:Yb,Tm,Er phosphors prepared by ammonium bicarbonate coprecipitation method:pH=7-8;calcination at900?for 4h;under the excitation of 980nm ultraviolet light,there is blue and green light emission.The best preparation process of Gd₂O_3:Yb,Tm,Er phosphors prepared by aqua ammonia coprecipitation method:pH=8-9;calcination at 900?for 4h;under the excitation of980nm ultraviolet light,there is blue and green emission.It is found that the XRD peak value and luminescent intensity of the samples with ammonium bicarbonate as precipitator are slightly higher than that of the samples with aqua ammonia as precipitator.Therefore,ammonium bicarbonate is the best precipitator for the preparation of Gd₂O_3:Yb,Tm,Er phosphors.