Preparation Of γ-Fe₂O₃ By Sol-gel Routine

With development of nomo-tech, namo- magnetism materials are applied more and more, including γ-Fe2O3 powder. Taking citrate-iron as initialized reactant, employing matured sol-gel way, together with ultrasonic, γ-Fe2O3 namo-powder is made in this research. The preparation conditions and capability of powder is studied by many measure ways, such as DTA, FT-IR, XRD, BET.The conclusion is as followed: the concentration of initialized reactant, namely citrate-iron, should be proper, extortionate concentration leads to severe agglomeration, while inadequate one leads to extremely little particle size, thus resulting in hard to syringe and agglomeration. The pH of solution is controlled by adding ammonia. Different pH effects not only size of final particle, but also its magnetism. The accession of activating chemist has a strong influence on agglomeration in particles. Oleate-sodium is adopted to control development of deposition and detract, and its effect is better than PEG and carbamide. The temperature of reaction also acts an important role. At low temperature, the reclaim rate is low and particles reunite into agglomeration, while at high temperature, particles size turns bigger.How the syringing way and drying temperature effects reunite is also studied. Using ethanol to replace water, and deal with reagent after percolation, in this way, agglomeration of particles reduces. The affection of different baking temperature on size of final powder is also explored in the paper. After many times of experiments we make a final conclusion that the temperature of 440C is the best, and the phase of production at this baking temperature is y. when reagent is baked, it should be heated preservation at 300 C then ascended at 440C. Ultrasonic works in the preparation. By comparing affection of ultrasonic and magnetic-whipping, it shows that the former way brings less particle size and agglomeration phenomenon.Counted by Scherrer formula, the particle size of final powder is 75.7nm, while average conglomeration size is 174nm, and its max magnetism is 49.9emu.g-1.