The Synthesis Of Doped Fe₃o₄ Nanocrystalline And Its Property Study

As an important category of nano-materials, magnetic nano-materials have not only the macro and micro features of nano-materials, but also some exclusive features, such as the apparent magnetism, superparamagnetism and so on, which cause great concern. Among the numerous magnetic nano-materials, nano Fe₃O₄ magnetic particles possess some special merits, such as simple production process, non-toxic, good biocompatibility, and so on. They have excellent application foreground in the fields of catalyst materials, magnetic recording materials, biopharmacy, etc. This article investigates systemically the preparation, characterization, doping modification mechanic analysis, and other related researches on the doped Fe₃O₄ magnetic particles.Doped Fe₃O₄ magnetic nanoparticles were prepared by the hydrothermal method. By analyzing the impact of the reactant ion ratio, hydrothermal temperature, reaction time, dosage of the surfactant and doping ion on the product, the best process condition to prepare the magnetic particles is determined: The optimum mol ratio of reactants is n(Fe²⁺):n(Fe³⁺):n(C₁₈H₂₉NaO₃S):n(C₁₈H₃₃NaO₂)=1:1.5:0.03:0.01; The most suitable reaction temperature is 160℃and the reaction time is 6h;In preparing the single-doped Fe₃O₄ magnetic nanoparticles using the hydrothermal method, the optimum doping amount of doping icon is: when the doping ion is Co²⁺, the optimum doping amount of doping ion is n(Fe³⁺+Fe²⁺):n(Co²⁺)= 15:1; when the doping ions is Ni²⁺, the optimum doping amount of doping ion is n(Fe³⁺+Fe²⁺):n(Ni²⁺)=15:1 and when the doping ion is Cd²⁺, the optimum doping amount of doping ion is n(Fe³⁺+Fe²⁺):n(Cd²⁺)= 15:1; The optimal molar ratio of doping ions among the doping icon is: When the doping ions are Co²⁺ and Ni²⁺, the optimal molar ratio of doping ions is n(Co²⁺):n(Ni²⁺)=1:1,When the doping ions are Co²⁺ and Cd²⁺, the optimal molar ratio of doping ions is n(Co²⁺):n(Cd²⁺)=2:1; When the doping ions are Ni²⁺ and Cd²⁺, the optimal molar ratio of doping ions is n(Ni²⁺):n(Cd²⁺)=2:1; X-ray diffraction (XRD), transmission electron microscopy (TEM) and AC gradient magnetor were applied to make related tests about the reaction product. The phase composition, microstructure, morphology and magnetic properties of the product were analyzed. The results showed that: the diffraction peak of the product is obvious, belonging to pure phase Fe₃O₄ nanoparticles, spinel structure, spherical, particle size of 10nm or so, showing good superparamagnetism, and the right amount of doping ion can increase the product's saturated magnetization.Doped Fe₃O₄ magnetic nanoparticles were prepared by the co-precipitation method. The impact of the reaction factors on the performance of the product is observed through the experiment. The optimum process conditions for preparing the product using this method was determined: the best ratio of reactants is n(Fe²⁺):n(Fe³⁺):n(C₁₈H₂₉NaO₃S): n(C₁₈H₃₃NaO₂)=1:1.5:0.03:0.01;The most suitable reaction temperature is 65℃and the reaction time is 3 hours.In the single-doped condition, the optimum doping amount of doping icon is: when the doping ion is Co²⁺, the doping ion's optimum doping amount is n(Fe³⁺+Fe²⁺):n(Co²⁺)= 15:1; when the doping ion is Ni²⁺, the doping ion's optimum doping amount is n(Fe³⁺+Fe²⁺):n(Ni²⁺)=15:1 and when the doping ion is Cd²⁺, the doping ion's optimum doping amount is n(Fe³⁺+Fe²⁺):n(Cd²⁺)= 15:1; while in the codoped condition, the optimal molar ratio of doping ions among the doping icon is: when the doping ions are Co²⁺ and Ni²⁺, the optimal molar ratio of doping ions is n(Co²⁺):n(Ni²⁺)=1:1, when the doping ions are Co²⁺ and Cd²⁺, the optimal molar ratio of doping ions is n(Co²⁺):n(Cd²⁺)=1:1; when the doping ions are Ni²⁺ and Cd²⁺, the optimal doping ion molar ratio is n(Ni²⁺): n (Cd²⁺) = 2:1. X-ray diffraction (XRD), transmission electron microscopy (TEM) and AC gradient magnetor were used to make related tests about the reaction product. During the process, the phase composition, microstructure, morphology and magnetic properties of the product were analyzed. The results showed that: the diffraction peak of the product is obvious, belonging to pure phase Fe₃O₄ nanoparticles, spinel structure, spherical, particle size of 8nm or so, showing good superparamagnetism, and the right amount of doping ion can increase the product's saturation magnetization.Finally, by comparing the two methods using data processing and characterization analysis, the effects of different doping ions and doping methods on the magnetic properties of the nano-Fe₃O₄ magnetic particles were discussed. The conclusions drawn from the article lay a good experimental foundation for the application research of nano-Fe₃O₄ magnetic particles in the biomedical field.