Hydrothermal formation and up‐conversion luminescence of Er³⁺‐doped GdNbO₄

Abstract

The effect of concentration of Er 3+ on the up-conversion and photoluminescence properties of Gd 1.00Àx Er x NbO 4 , x=0-0.50 which has monoclinic fergusonite-type structure as a main phase has been investigated, using a processing technique based on hydrothermal method. Under weakly basic hydrothermal condition at 240°C for 5 hours, a single phase of fergusonite-type Gd 1.00Àx Er x NbO 4 solid solution was directly formed as nanocrystals by the substitutional incorporation of Er 3+ into GdNbO 4 because of the gradual and linear decrease in the lattice parameters of the monoclinic phase corresponding to the Vegard's Law. The gadolinium niobate doped with 2 mol% Er 3+ , Gd 0.98 Er 0.02 NbO 4 after heating at 1300°C for 1 hour, which has nanocrystalline structure whose crystallite size is around 29 nm, exhibits the highest photoluminescence intensity in the green spectral region, 515-560 nm under excitation at wavelength of 254 nm. On the other hand, the up-converted luminescence intensity of the niobate nanocrystals becomes the maximum at the concentration of 20 mol% Er 3+ , Gd 0.80 Er 0.20 NbO 4 under excitation at 980 nm. These results demonstrate that the material, Er 3+doped GdNbO 4 nanocrystals prepared through hydrothermal route and postheating has potential for up-converting phosphor. K E Y W O R D S gadolinium niobate, GdNbO 4 , hydrothermal synthesis, up-conversion luminescence

Thulium Oxide Nanopowders Obtained by Precipitation

“…The rare-earth oxide powders can be prepared in many ways, for example, precipitation, hydrothermal synthesis, solgel, and combustion method. [31][32][33][34][35][36] In our previous work, 30 thulium oxide was obtained by precipitation method using three types of precipitants ammonium carbonate, ammonium hydrogen carbonate (AHC), and ammonia. Microscopic observations have proved a strong influence of the kind of precipitation agent used on shape and size of Tm 2 O 3 powder particles and finally on both microstructure and transmission of the obtained Tm:YAG ceramics.…”

Preparation, structure and up-conversion luminescence properties of novel cryolite K3YF6:Er3+, Yb3+

“…Four emission peaks at 524, 546, 661 and 672 nm in the green and red regions can be founded, which can be ascribed to the transitions from 2 H 11/2 , 4 S 3/2 , 4 F 9/2, and 4 I 9/2 states to 4 I 15/2 state of Er 3+ , respectively. 38,39 The inset shows the effect of Yb 3+ doping ratio on the luminescence intensity of the K 3 YF 6 :0.03Er 3+ , yYb 3+ (y ¼ 0.01, 0.03, 0.07, 0.09, 0.12, 0.15 and 0.18). With the increasing for Yb 3+ from 0.01 to 0.18, the emission intensity of the samples rstly increased and then decreased.…”

Hydrothermal synthesis of luminescent niobate thin rods

“…In order to improve the performance and properties of inorganic materials, the investigation on their synthesis techniques is an efficient way. 15), 16) Therefore, various investigations on the preparation of CaNb 2 O 6 using solidstate reaction, 4),7), 12) flux growth, 17) laser-heated pedestal growth, 10) glycothermal, 18) solgel, 19) and coprecipitation method 20) have been carried out. In recent years, from a viewpoint of green processing, great attention has also been devoted to a direct synthesis of fine inorganic materials at low temperatures.…”