Preparation And Characterization Of One-dimensional Nanoscale Rare Earth Compounds

One dimensional (1D) nanomaterials have attracted much interest throughout the world because of their unique quantum and confine effects, as well as their excellent optical, electrical, magnetic, mechanical and thermal properties. Lanthanide has the chemical activity, numerous physical and chemical characterizations depending on its unique electronic structure (4fo+n5d0¹6s2). 1D lanthanide nanomaterials have drawn much attention as the development of 1D nanomaterials. We studied the synthesis and growth mechanism of 1D lanthanide hydroxides and oxides via soft chemical method. We fabricated some novel structures by aqueous self-assembly technique. The main research results in this thesis are as follows:(1) Lathanide hydroxide nanobelts and nanowires are synthesized successfully by composite-hydroxide-mediate (CHM) method. The spindle-like Nd(OH)₃,Sm(OH)₃,Eu(OH)₃ nanoparticles self-assembled by many nanowires are prepared through a aqueous self-assembly technique without any surfactant and template. We studied the growth mechanism of the products. This process provides a general methodology for the preparation of other 1D lanthanide nanocompounds.(2) We have developed a new strategy for the synthesis of La(OH)₃:Eu³⁺ ultra-long nanowires and nanoprisms. After subsequent heat treatment, the La₂O₃:Eu³⁺ is obtained and inherits the corresponding morphology. The growth mechanisms of two products are presented. The results show that La₂O₃: Eu³⁺ nanorods exhibit a strong red emission corresponding to 5D0â†'7F2 transition (625 nm) of Eu³⁺ under UV light excitation (282 nm), which has potential applications in fluorescent devices.(3) We have developed a new strategy for the preparation of lanthanide hydroxide nanorods using H₂O₂ as the templatel agent by a hydrothermal process. The aggregation-dissolution-recrystalline-growth mechanism is presented. The La₂O₃:Eu³⁺ nanorods are obtained by heat treatment. The results show that these products have the higher BET specific surface areas, and exhibit a strong red emission under UV light excitation.