In this paper, a fast and facile microwave method is described to prepare monoclinic ScP04·2H2O flowerlike superstructures constructed by well-aligned nanorods without use of any template or surfactant. By varying the preparation parameters, such as reactant ratio, microwave power and reaction time, various morphologies, such as nanospheres, cubes and particles were obtained. The growth process of the flowerlike microstructure was also investigated. A nanorod growth and self-assembling process was involved in the formation of the flowerlike superstructure. After calcining the ScP04·2H2O microflowers at 800 °C, tetragonal ScP04 with similar morphology was obtained. Tb3+, Eu3+, Dy3+, Tb3+/Eu3+ and Eu3+/Dy3+ doped ScP04·2H2O were also prepared and their photoluminescent properties investigated. By adjusting the relative doping concentration, multicolor tunable emission of green, red and blue could be realized and the decay time results reveal that energy transfer occurs. More significantly, white light could be achieved in a 3% Eu3+ and 2% Dy3+ co-doped ScP04·2H2O. First-principles calculations were carried out to study the structural and electronic properties, which were in accordance with the experimental observations.
Jun Yang,Jingjing Cao,Dingyi Shen,Jie Xiong,Jianfeng Tang,Shanshan Hu
Well-crystallized and uniform ScPO4·2H2O and ScPO4·2H2O:Ln3+ (Ln = Ce, Eu, Tb, Lu) nano/micro-crystals with multiform morphologies, such as sphere, hexagonal plate, diamond, four-angle star, butterfly-shaped and cuboid, have been successfully synthesized by a facile hydrothermal route without any surfactant molecules. XRD, FE-SEM, TEM, PL and kinetic decay were used to characterize the as-prepared products. The size and morphology of ScPO4·2H2O can be determined by the pH value, reaction time, reaction temperature, additive and doping of lanthanide ions. In particular, Ln3+ doping not only has a crucial role in the morphology of ScPO4·2H2O, but also affects its luminescence properties. The ScPO4·2H2O:Tb3+ and ScPO4·2H2O:Ce3+ samples display intense green and blue emissions, respectively. More importantly, the luminescence properties are closely related to morphologies and crystallinity. It can be found that the ScPO4·2H2O:Tb3+ sample with a hexagonal plate-like morphology possesses much higher emission intensity than those with other morphologies because of its larger anisotropic geometry. ScPO4:Ln3+ crystals will become promising candidates for a variety of applications in down/up-conversion luminescence, magnets, lasers, and bio-labeling.
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