Preparation And Luminescent Properties Of Rare Earth Ions Doped Nanomaterials

Rare earth luminescent materials have shown a lot of characteristic different from the tradition of the bulk light-emitting materials, and possessed potentially high quantum luminescence efficiency and resolution. Hence, the synthesis of high efficiency, good mechanical strength and chemical stability of rare earth doped luminescent materials under appropriate host and reaction conditions is the main purpose of investigators. Er3+ ion is rich in emission level from ultraviolet to near infrared, efficient up-conversion luminescence can be achieved when Er3+ ion used as active ions.Therefore, the investigation of Er3+ doped up-conversion luminescence materials is important in the theoretical study and practical application. However, little is reported about BaF2 nanorods.In this paper, the history of up-conversion luminescence, recent progress were reviewed, and the luminescent mechanism, characteristic, classification, preparation and investigation method, characterization means and application prospect were introduced. Then, Rare-earth doped oxide nanomaterials were synthesized by hydrothermal method and combustion method, respectively. Finally, Eu3+ doped one-dimensional nanorods and microrods were prepared using hydrothermal method and their luminescent properties were compared. The major results are listed as follows:(1) Y2O3:Er3+,Yb3+ nanoparticles were synthesized by hydrothermal method. The results showed that, the structure of the samples annealed at 1200℃are pure cubic phase, their rod-like morphology were about 100 nm in diameter and are close to micron level in length. Up-conversion luminescence of blue (408nm), green (520~570nm) and red (650~670nm) was observed under the excitation of 980 nm, which was due to the transitions of 2H9/2→4I15/2, 2H11/2, 4S3/2,→4I15/2 and 4F9/2→4I15/2, respectively.(2) Y2O3:Er3+,Gd3+,Yb3+ nanoparticles were synthesized by combustion method and the samples all belonged to cubic phase annealed at different temperature. The results confirmed that the Y2O3:Er3+,Gd3+,Yb3+ nanoparticles without complicated phase can be prepared using combustion method.Under the excitation of 980 nm, the up-conversion luminescence of blue (408nm),green (520~570nm) and red (650~670nm) were observed in Y2O3:Er3+,Gd3+,Yb3+ nanoparticles, which were due to the transitions of 4F7/2→4I15/2, 2H11/2, 4S3/2,→4I15/2 and 4F9/2→4I15/2, respectively. The emission intensity of the samples increased gradually with the increase of annealing temperature. Considering the actual conditions of industrial production and energy consumption, the annealing temperature at 800℃was selected which may be more efficient.(3) BaF2:Eu3+ microrods and nanorods were synthesized using microemulsion-assisted solvothermal method. The results indicated that: the products were single crystals without impurities, the microrods formed three-dimensional structure while the nanorods was one-dimensional. Under the excitation of ultraviolet light, the luminescence properties of the rod-like sample were different from those of BaF2:Eu3+ nanocrystallites. The surface disfigurement of the sample had significant influence on the nanorods photoluminescence processes, which lead to the decrease in the relative luminous intensity of nanorods.