Dna-Assisted Synthesis And Characterization Of Micro- Or Nano-Barium Fluoride Crystaline

With intercrossing and infiltrating of Biology and Nano-chemistry, synthesizing nanomaterials with special morphologies using bio-molecules as templates has drawn considerable interest. Besides, it's also a potential development direction in the field of controllable synthesis of micro/nano materials. In this paper, DNA, with high self-recognition and self-assembly capability, was chosen as the template to synthesize micro/nano BaF₂ crystalline. The products were analyzed and characterized by Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectrometer (EDS), Selected Area Electron Diffraction (SAED), X-ray Diffraction (XRD) and Fluorescence Spectrometer (PL).With the assistance of DNA molecule, controllable growth of BaF₂ particles on DNA chains was realized. Morphology and organization of BaF₂ particles on DNA could be controlled by altering the reaction conditions. For example, square nanoparticles were gained with assistance of normal DNA; while, under the assistance of denatured DNA, helianthus-shaped and hollow-centered BaF₂ particles were synthesized, and the inner and outer diameters were 200 and 400 nm respectively. Besides, we studied the effect of solvent, temperature and heating time on the products, and also discussed the possible mechanism of circular structure. At the end of chapter 3, the mechanism of DNA-assistance was discussed.On the basis of DNA-assistance synthesis of pure BaF₂, we doped 1% Eu³⁺ into BaF₂ crystal cell, and prepared Eu³⁺:BaF₂. By TEM observation, it turned out that the particles of BaF₂ doped Eu³⁺ were not square any more, but irregular with only several nanometers; and a large quantity of particles congregated together. The transmittance property was well in the range of violet and near-infrared, and was improved compared with undoped. In PL spectrum, typical Eu³⁺ luminescence with high intensity was observed in the range of 550-750 nm, which indicated the good luminescent property of Eu³⁺:BaF₂. It may be used as luminescent material.