The Preparation And Application Of Zn_xFe_3-xO₄ Nanoparticles And Magnetic Fluids

The effect of the technological parameters such as the reacting temperature, the reacting time and the concentration of reactant on the formation and the particle size of Zn_xFe_3-xO₄(x=0.1-0.5) nanopowders, which are prepared by chemical coprecipitation method, has been explored. The best reacting condition was found, then a series of Zn_xFe_3-xO₄(x=0.1-0.3) nanopowders were made, their specific saturation magnetization were measured and analysed. Using modified chemical coprecipitation method, the more dispered Zno.2Fe2.gO4 nanopowder was prepared, then using this nanopowder, a series of magnetic fluids were prepared. A magnetic fluid rotary shaft seal mechanism was designed. In addition, according to our modified technology, the method and facility to prodce magnetic fluid were designed.The results show that the particle sizes are about 8 nm and the crystal structure is spinel, when the reacting temperature is 60℃,the reacting time is 4 minute and the reactant concentration is 1 mol / L. In Zn_xFe_3-xO₄ nanoparticles, at first the specific saturation magnetization(σ_s) increase with the increase of content of Zn²⁺(x), when x is 0.2, σ_s is biggest, which is 63.07Am²/kg, thenσ_s is decrease with the increase of x.Using modified chemical coprecipitation method and using oleic acid as surfactants, not only the agglomeration problem can be solved, at the same time, the Zn_xFe_3-xO₄ nanoparticles, whose particle diameter is at 6-8nm, can be prepared. The magnetic fluids show superparamagnetic in the applied magnetic field and the specific saturation magnetization increase with the density, the utmost value is up to 29.93 Am²/kg.