Study On Synthesis, Characterization And Properties Of Different Morphology Nb-based And W-based Nanomaterials

The effects of different synthysis conditions by solvothermal method on generation of nanomaterials,different reacting conditions by gas-solid reaction on modify of nanomaterials have been investigated in this work.The nanomaterials were charactered by SEM,TEM,XRD,IR,XPS and Raman techelonegies.These works as fellow:(1) Novel orthorhombic Nb₂O₅ nanorods and polygonal Nb₂O₅ platelets have been generated by a simple solvothermal technique.The geometry evolution of the resultant Nb₂O₅ from amorphous nanoparticles to crystallized particles,from polygonal platelets to well-elongated nanorods has been studied in detail.The processing parameters,including the reaction temperatures,reaction time,concentration of the precursors,and pH values of the solution,that affect the shape and size of the nanorods have been investigated.The nanomaterials were charactered by SEM,TEM and XRD technologies.(2) One-dimensional(1-D) NbS₂/Nb₂O₅ nanocables have been generated by a two-step process,a simple solvothermal technique for a Nb₂O₅ nanorod core and subsequent reaction with H₂S to form the NbS₂ shells at 800℃.Under optimal conversion conditions,the final geometry features of the sulfide-sheathed oxide nanocables are predetermined by the size and morphology of the Nb₂O₅ nanorods which grow along the equivalent crystallographic directions of[110]in the orthorhombic Nb₂O₅.Three-dimensional(3-D) Nb₂O₅/NbS₂ cabled networks have been synthesized via gas-solid reactions between the three-dimensional(3-D) Nb₂O₅ single crystalline nanostructures and H₂S gas.The nanostructures produced by 3 min sulphidization usually consist of 2-5 layers of lattice fringe.Those reacted for 6 min comprise 4-10 NbS₂ layers.(3) The reactions of the Nb₂O₅ nanoplatelets with NH₃ or the reactions of the Nb₂O₅ nanorods with NH₃ lead to another two types of interesting structures:The Nb_3.49N_4.56O_0.44 nanoplatelets and the Nb_3.49N_4.56O_0.44 nanorods.The Nb₂O₅ nanoplatelets can be employed asprecursors for the creation of the Nb_3.49N_4.56O_0.44 nanoplatelets and the Nb_3.49N_4.56O_0.44 nanorods.By modifying the processing parameters,we have subsequently achieved nanoplatelets and nanorods with tuneable geometry identical to their parent oxide nanoplatelets,which is important for understanding nanostructure processing.(4) we describe the first successful creation of 1-D Fe-doped tungsten oxide and ferberite nanowires by employing a simple solvothermal technique,and then uncover the interesting evolution secrets toward a class of complex and amazingly elegant 3-D flower-like structures made of 6-folded blades of ferberite.It is found that different Fe ions addition has a profound impact on the geometry and morphology of the products.The resulting nanostructures obtained under diverse Fe ions additions in respective chloride solvents demonstrate clearly the geometry evolution routes of these structures,from long and fine(bundled and ultra thin) WO₃ nanowires to short and heavily bundled nanowires, and to irregular mixture of short nanowires and nanoplatelets,then to 'desert rose' type structures accompanied with many nanoparticles,and eventually to completely converted 3-D nanoflowers,along with the increase of the Fe concentration.