Silica encapsulation and magnetic properties of FePt nanoparticles

Aslam, M.; Fu, Lei; Li, S.; Dravid, Vinayak P.

doi:10.1016/j.jcis.2005.04.050

Cited by 89 publications

(60 citation statements)

References 24 publications

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“…Ferromagnetic resonance measurements on these water-soluble FePt nanoparticles do not indicate oxidation of the FePt core, [56] proving the chemical stability of the FePt nanoparticles. Surfactant exchange has been further extended to coat the thiol-based molecules [57][58][59] and silica [60,61] over the FePt surface to make FePt nanoparticles water soluble. The high affinity of FePt for S allows the preparation of multifunctional nanoparticles.…”

Section: Surface Chemistry Of Fept Nanoparticlesmentioning

confidence: 99%

Recent Advances in Chemical Synthesis, Self‐Assembly, and Applications of FePt Nanoparticles

2006

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This paper reviews recent advances in chemical synthesis, self‐assembly, and potential applications of monodisperse binary FePt nanoparticles. After a brief introduction to nanomagnetism and conventional processes of fabricating FePt nanoparticles, the paper focuses on recent developments in solution‐phase syntheses of monodisperse FePt nanoparticles and their self‐assembly into nanoparticle superlattices. The paper further outlines the surface, structural, and magnetic properties of the FePt nanoparticles and gives examples of three potential applications in data storage, permanent magnetic nanocomposites, and biomedicine.

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Section: Surface Chemistry Of Fept Nanoparticlesmentioning

confidence: 99%

Recent Advances in Chemical Synthesis, Self‐Assembly, and Applications of FePt Nanoparticles

2006

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“…Although a Fe 3 O 4 shell can be formed [15] by the thermal decomposition method, the shell degrades at temperatures less than 600°C and destroys the nanoparticle structure and shape. Techniques to coat a silica shell on clusters of magnetic nanoparticles that have been presynthesized using a separate processing method have been demonstrated, [21][22][23] but these techniques are not well suited for creating organized assemblies of well-separated nanoparticles for recording media applications. Here, we report the room-temperature synthesis of monodisperse FePt nanoparticles with tunable particle size over an extended range of 4-20 nm and excellent compositional control using microemulsions.…”

mentioning

confidence: 99%

Synthesis and Assembly of Monodisperse High‐Coercivity Silica‐Capped FePt Nanomagnets of Tunable Size, Composition, and Thermal Stability from Microemulsions

et al. 2006

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The large uniaxial magnetic anisotropy energy ) [1,2] of Fe-Pt alloys makes their nanostructured forms attractive for potential use as nanoscale magnetic bits in ultrahigh-density information storage devices [3][4][5][6][7] or as fillers to create new types of magnetocomposites. The high magnetic anisotropy and coercivity arise from the chemically ordered face-centered-tetragonal (fct) L1 0 phase, which is sensitive to both chemical composition and the size of the nanoparticles. [4,8,9] Control over particle size and dispersity [10][11][12][13] is essential to form ordered arrays of nanoparticles, and preserve these features against agglomeration [14,15] during high-temperature annealing (e.g., 550°C) treatments used to obtain the L1 0 phase. Therefore, it is crucial to develop protocols to produce FePt nanoparticles with control over composition, particle size, and dispersity, and thermal stability for exploiting their assemblies for data-storage media applications. The synthesis technique described here is a promising approach to realize all these features simultaneously.Prior works have demonstrated FePt nanoparticles synthesis with either excellent size control [3][4][5]10,16] or chemical compositional control [17][18][19] but not both. Thermal decomposition of Fe(CO) 5 vapor, and reduction of Pt(acac) 2 , produces monodisperse nanoparticles with tunable sizes in the 2-15 nm range. [3][4][5]20] But, the chemical composition of the nanoparticle is different from the initial molar ratio of the metal precursors due to different precursor decomposition rates.[10] Size control is further complicated by the strong influence of parameters such as Ar gas flow rate, heating rate, and temperature.[ [19] of the initial molar ratio of the metal precursors, but the particle size is constrained to a limited range of approximately 3-5 nm. Neither of these two synthesis routes is easily amenable to coating the nanoparticles with a protective shell of a thermally stable material (e.g., silica or titania) that could prevent particle shape and size changes during postsynthesis annealing for obtaining the L1 0 phase. Although a Fe 3 O 4 shell can be formed [15] by the thermal decomposition method, the shell degrades at temperatures less than 600°C and destroys the nanoparticle structure and shape. Techniques to coat a silica shell on clusters of magnetic nanoparticles that have been presynthesized using a separate processing method have been demonstrated, [21][22][23] but these techniques are not well suited for creating organized assemblies of well-separated nanoparticles for recording media applications. Here, we report the room-temperature synthesis of monodisperse FePt nanoparticles with tunable particle size over an extended range of 4-20 nm and excellent compositional control using microemulsions. We further use the same microemulsion to enhance the nanoparticle thermal stability by forming a 2 nm thick silica shell, which is also used for functionalization with organosilanes. Organized assemblies formed from the molecul...

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“…[30][31][32][33] The magnetic property of FePt NPs is not only strongly correlated with the degree of chemical ordering of the alloy, but also influenced by the composition and surface coating of the alloy. [44][45][46] The surface iron sites are the primary contributors to the magnetization in FePt. 4,000 3,500 3,000 2,500 2,000 1,500 1,000 500…”

Section: Resultsmentioning

confidence: 99%

Water-soluble l-cysteine-coated FePt nanoparticles as dual MRI/CT imaging contrast agent for glioma

Liang¹,

Zhou²,

Wang³

et al. 2015

IJN

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Nanoparticles (NPs) are advantageous for the delivery of diagnosis agents to brain tumors. In this study, we attempted to develop an l -cysteine coated FePt (FePt-Cys) NP as MRI/CT imaging contrast agent for the diagnosis of malignant gliomas. FePt-Cys NPs were synthesized through a co-reduction route, which was characterized by transmission electron microscopy, high-resolution transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, and dynamic light scattering. The MRI and CT imaging ability of FePt-Cys NPs was evaluated using different gliomas cells (C6, SGH44, U251) as the model. Furthermore, the biocompatibility of the as-synthesized FePt-Cys NPs was evaluated using three different cell lines (ECV304, L929, and HEK293) as the model. The results showed that FePt-Cys NPs displayed excellent biocompatibility and good MRI/CT imaging ability, thereby indicating promising potential as a dual MRI/CT contrast agent for the diagnosis of brain malignant gliomas.

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Silica encapsulation and magnetic properties of FePt nanoparticles

Cited by 89 publications

References 24 publications

Recent Advances in Chemical Synthesis, Self‐Assembly, and Applications of FePt Nanoparticles

Recent Advances in Chemical Synthesis, Self‐Assembly, and Applications of FePt Nanoparticles

Synthesis and Assembly of Monodisperse High‐Coercivity Silica‐Capped FePt Nanomagnets of Tunable Size, Composition, and Thermal Stability from Microemulsions

Water-soluble l-cysteine-coated FePt nanoparticles as dual MRI/CT imaging contrast agent for glioma

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