Shape-Controlled Synthesis Of Nanoscale Luminescence Materials In Hydrothermal Aproach

As we all knew that nanomaterials exhibit a wide range of physical and chemical properties that depend sensitively on both size and shape, and are of both fundamental and technological interest. Nanomaterials shape control is one of the most important research points. There are two kinds of shape control method: controlling the growth kinetics and using a template. Here, we use these two methods to achieve shape control and get some new results.Hexagonal wurtzite structure Tb(OH)₃ nanowires with a uniform diameter have been synthesized on a large scale via a hydrothermal treatment based on the use of an anodic aluminum membrane (AAM) as template. Aligned Tb(OH)₃ nanowire arrays can be obtained by dissolving the template. Furthermore, a growth mechanism of the Tb(OH)₃ nanowires using hydrothermal-template synthesis technique has preliminarily been proposed. This approach greatly conquers the difficulties encountered in the template-based preparation methods used previously, such as the CVD, the sol-gel and the electrochemical deposition. The hydrothermal-template method opens up a new way to synthesize many other types of nanowires and nanowire arrays, and widen the applications of the AAM-assisted synthesis technique.Highly uniform and monodisperse YF3 nano- and submicro-sized truncated octahedra are successfully prepared in large quantities using a facile hydrothermal approach assisted by a capping reagent, ethylenediamine tetraacetic acid disodium salt (Na₂H₂EDTA). The formation mechanism of the YF3 truncated octahedra is discussed. Our study shows that the results for different rare earth fluorides are similar to each other, but the images have some differences due to different crystal structures. These synthetic and mechanistic studies may be the basis for controlling the geometry of a wide range of nano/micro particles, and more importantly, for the success of bottom-up approaches toward future devices.Highly uniform and monodisperse Eu:YF₃ nano- and submicro-sized truncated octahedra are successfully prepared in large quantities using a facile hydrothermal approach assisted by a capping reagent, ethylenediamine tetraacetic acid disodium salt (Na₂H₂EDTA). The photoluminescence spectra at room temperature show that except for the characteristic red emission peaks of Eu³⁺, an intense blue emission band centered at about 445 nm originating from the 4f⁶5d to 4f⁷ configuration in Eu²⁺ is also observed when excited at 393 nm, which is quite different from those reported previously. The results reveal that there should be a redox reaction during hydrothermal preparation of YF₃:Eu at 180°C, and some of the Eu³⁺ ions should have been reduced to the divalent state in the preparation process. The intense 390-nm emission for YF₃:Eu may be found applications in the near future. This preparation method provides a simple route to synthesize other fluoride nanophosphors.Complex 3Dα-MnS flowerlike hierarchical architectures with 1-2μm in diameter built up of ultrathin nanosheets have been synthesized firstly by a simply hydrothermal method free from templates or matrixes and organic additives. Adjacent flowerlike architectures can further expand and eventually self-assembled themselves into interconnected porous continuous networks. Studies show that the formation of complexes in the reaction system is vital to the morphology of the final product. The simplicity of the fabrication process described herein would open up the possibility of being further explored to create other complex forms with extremely high surface-to volume ratio and brings new insights into the underlying mineralization mechanisms of complex nanoarchitectures in the natural and synthetic world.