The Mixed Solvothermal Synthesis, Characterization And Properties Of Magnetism

Our work concludes two parts. First, Fe₃O₄ hollow microsphere chains was synthesised in glycerol- water mixed solvent system. Fe₃O₄ octahedral chains can be formed with changing the pH value, and the magnetic properties of these two chains were studied. Second,α-Fe₂O₃ porous structures were synthesised in mixed solvent system consisted of acetic acid - water, THF - water, and TEPA- water. A contrastive study was made on the surface area of them. The main points list as follows:1. Fe₃O₄ hollow microsphere chains with length of 8-11μm have been solvothermally synthesized in the mixed solution of glycerol and water with 1 M NaOH. The hollow microspheres are 0.7-1μm in diameters and the thickness of the shells is 150-300 nm. The shell of the hollow microspheres is constructed by octahedrons of 100-170 nm. However, when the concentration of NaOH is adjusted to 3 M, the octahedron chains with length of 30-50μm can be obtained. The magnetic saturation values of hollow microsphere chains and octahedron chains are 88.1 and 102.4 emu/g at room temperature, respectively.2. Three differentα-Fe₂O₃ porous structures were successfully synthesised by mixed solvent systems consisted of acetic acid - water, THF - water, and TEPA– water. The morphologies are porous nanospheres, porous microcube, and porous nanoparticles. All the porous structure were synthesised by one pot method, and did not need high temperature calcination. The porous microcube morphology has a distinctive feature, which is crack growth trend is found in the particles on the edge during the synthesis procedure, and has a larger hole density. The samples were characterized using XRD, TEM, SEM, etc. The surface area properties of theseα-Fe₂O₃ were studied. At last, magnetic properties of porous microcubes were measured at 300 k and 5 K, respectively.