What is Fe3O4?
Exceptional magnetic properties of magnetite, Fe3O4, and nanoparticles make them one of the most intensively studied inorganic nanomaterials for biomedical applications. We report successful gram-scale syntheses of colloidal Fe3O4 nanoparticles with sizes of 12.9 ± 5.9, 17.9 ± 4.4, and 19.8 ± 3.2 nm via hydrothermal route or controlled coprecipitation in an automated reactor. To investigate structure−property relationships as a function of the synthetic procedure, we used multiple techniques to characterize these nanoparticles' structure, phase composition, and magnetic behavior. For the iron oxide cores of these nanoparticles, powder X-ray diffraction and electron microscopy both confirm single-phase Fe3O4 composition. In addition to the core composition, the magnetic performance of nanoparticles in the 13−20 nm size range can be strongly influenced by the surface properties, which we analyzed with three complementary techniques.
Naturally ferrimagnetic (FiM) magnetite, Fe3O4
With a multidomain magnetic structure, an iron oxide polymorph appealing for various applications because bulk Fe3O4 exhibits a high Curie temperature (TC bulk = 840 K) and the highest saturation magnetization (Ms bulk = 98 emu/g) among iron oxides.1 In nanoparticle (NP) form, the magnetic behavior of Fe3O4 is predominantly determined by the size of the particles. FiM Fe3O4 NPs transition from multi- to single-domain magnetic structure as their size is reduced below 80−90 nm.2 Upon further size reduction to 25−30 nm, Fe3O4 NPs turn into a superparamagnetic (SPM) state at room temperature (RT) as a consequence of the spontaneous flip of their magnetization (M), which is determined by the balance between thermal energy and magnetic anisotropy.2 SPM NPs are desirable for preparing colloidally stable dispersions because larger (≥25−30 nm) FiM NPs exhibit remanence and coercive forces that cause aggregation under a magnetic field. Colloidally stable SPM NPs exhibit a high Ms, good chemical stability, biocompatibility,3, and low toxicity.
Optimizing SPM Fe3O4 NPs for specific applications requires improvements in two critical areas
(1) synthesis of NPs having a large size (around 20 nm) and relatively narrow size distribution, and (2) elucidation of their structure and phase composition to determine structure−property relationships. A narrow particle size distribution around 20 nm maximizes Ms while reducing the undesirable FiM contribution of large NPs, which increases with polydispersity. The majority of the methods used to prepare Fe3O4 NPs lead to particle sizes of about 10 nm and correspondingly low Ms values, following the general particle-size dependence of Ms. 6. In contrast, Ms values are as high as 85 emu/g (at 2 K) have been achieved for larger (20 nm) NPs;7 gram-scale synthesis of such large NPs, however, is difficult.8 Large colloidal SPM Fe3O4 NPs have been prepared mainly by three routes: (1) thermal decomposition,9 (2) mild oxidation of Fe2+ precursor10 followed by stabilization of the resultant NPs in colloidal form,11 and (3) the classical synthesis of 10 nm NPs by coprecipitation followed by hydrothermal growth of the particles.12 The limited number of available synthesis methods motivates the developing of new protocols to prepare large SPM Fe3O4 NPs.
Price of Fe3O4
Fe3O4 particle size and purity will affect the product's Price, and the purchase volume can also affect the cost of Fe3O4. A large amount of large amount will be lower. The Price of Fe3O4 is on our company's official website.
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