Synthesis, Intercalation And Luminescence Performances On The New Members Of The Layered Rare-Earth Hydroxides Functional Materials

Layered rare-earth hydroxides (LRHs) are one family of inorganic lamellar materials that consist of pure lanthanide cations (Ln3+) in the host layer and charge-balancing anions in the interlayer regions which can be readily replaced by other species through an anion exchange process. The virtues of rare-earth ions and layered structure are simultaneously existed in these kinds of layered materials so that they are potential novel functional materials. The main point of this thesis is as follows:1. The new members of the layered rare-earth hydroxide (LRHs) family with the generalized formula (Yl-xREx)2(OH)5NO3·nH2O (RE= Tb, Eu; 0≤x≤1) (YRE-LRHs) and YTbEu-LRH have been synthesized via a hydrothermal route. Detailed crystal structures and elemental compositions have been investigated by X-ray diffraction (XRD), elemental analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The layered structure of LRHs held when the other lanthanide ions were introduced into their layer. The YTb-LRHs samples exhibit the most intensive luminescence of 5D4→7F5 (546 nm) and the YEu-LRHs samples have the most intensive luminescence for 5D0→7F2 (614 nm). The concentration quenching of YTb-LRHs and YEu-LRHs existed, and when Tb3+ and Eu3+ molar ratio reach 50 at% and 60 at%, respectively, the PL emission intensity of the YTb-LRHs and YEu-LRHs reach the maximum value. Moreover, the YTb-LRH samples with different intensity ratio of the blue emission peak at 420 (5D3-7F5,I1) to green one at 546 nm (5D4-7F5,I2), and the YEu-LRH samples with red emission peak at 614 (5D0-7F2,I3) to orange one at 590 nm (5D4-7F5,I4) can be obtained, and the luminescence can be tuned by controlling the ratios of the RE3+ ions in the layer.2. The tris (8-hydroxyquinoline-5-sulfonate) aluminum (AlQs) and dodecylsulfate anion (DS) were co-intercalated into the YTb-LRHs via a anion exchange reactions. The AlQs and DS in the YTb-AlQs/DS-LRHs were combined with the LRH layer by electrostatic interaction and hydrogen bonds, and they located in the interlayer gallery between LRH layers with a monolayer arrangement mode. Moreover, The optical propeties of these samples were investigated by varying the molar ratio of Tb3+ and AlQs. From the emission spectra it can be concluded that YTb-AlQs/DS-LRHs samples can exhibit different luminescence with different anionic content.3. The Y2O3:RE3+ powders were prepared by high temperature calcination of YRE-LRH precusors. It was found that with the increase of the calcination temperature, the average crystalline size of these samples were gradually increased. The high temperature quenched the luminescence of Y2O3:Tb, while the luminescence of Y2O3:Eu are enhanced as the temperature increases.