Shapes, multiple twins and surface structures of monodisperse FePt magnetic nanocrystals

Dai, Z. R.; Sun, Shouheng; Wang, Zhong Lin

doi:10.1016/s0039-6028(02)01384-5

Cited by 106 publications

(71 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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.…”

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

View full text Add to dashboard Cite

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...

show abstract

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

View full text Add to dashboard Cite

show abstract

“…2(d)) in the synthesized nanoparticles. These crystallographic stacking faults could also enhance the magnetic properties of the nanoparticles [37][38][39]. The stacking faults were also reported to relax the strain in the nanoparticles [37,38], thus influence the magneoelastic energy.…”

Section: Methodsmentioning

confidence: 94%

Simple top-down preparation of magnetic Bi_0.9Gd_0.1Fe_1−xTi_xO₃nanoparticles by ultrasonication of multiferroic bulk material

et al. 2014

View full text Add to dashboard Cite

We present a simple technique to synthesize ultrafine nanoparticles directly from bulk multiferroic perovskite powder. The starting materials, which were ceramic pellets of the nominal compositions of Bi0.9Gd0.1Fe1−xTixO3 (x = 0.00-0.20), were prepared initially by a solid state reaction technique, then ground into micrometer-sized powders and mixed with isopropanol or water in an ultrasonic bath. The particle size was studied as a function of sonication time with transmission electron microscopic imaging and electron diffraction that confirmed the formation of a large fraction of single-crystalline nanoparticles with a mean size of 11-13 nm. A significant improvement in the magnetic behavior of Bi0.9Gd0.1Fe1−xTixO3 nanoparticles compared to their bulk counterparts was observed at room temperature. This sonication technique may be considered as a simple and promising route to prepare ultrafine nanoparticles for functional applications.

show abstract

“…[1,2]. As a result, the metastable phases can be obtained because of the high cooling rate, high degrees of deformation or both [3,4].…”

Section: Introductionmentioning

confidence: 99%

On the Possibility to Control an Atom Motion in a FCC Iron Nanocluster

Bondarenko

Nedolya

2018

Acta Phys. Pol. A

View full text Add to dashboard Cite

The energy of the isolated iron nanocluster was calculated by molecular mechanics method using the LennardJones potential depending on the position of impurity carbon atom and substitutional atoms of nickel. The cluster included a carbon atom, that drifted from an inside octahedral interstice to a direction x022y to the surface directly or to a tetrahedral interstice in x111y direction and after that in x222y direction to the surface. In addition one of 14 iron atoms was replaced by a nickel atom (or pair atoms), the position of which was changing during simulation. It is shown that there were positions of a nickel atom that significantly affected nanoclusters energy. The calculation results indicated that position of a carbon atom in the octahedral interstice was more energetically favorable than tetrahedral interstice in the case of fcc nanocluster. On the other side, the potential barrier was smaller in the direction x111y than in the direction x022y. This indicates that there are two ways for carbon atom to drift to the surface of the nanocluster. The positions of nickel atoms were identified, which significantly affected the height of potential barriers of a tetrahedral and an octahedral interstice and determined the possible direction of carbon atoms drift. This allows manipulating atoms at the surface of nanocluster.

show abstract

Shapes, multiple twins and surface structures of monodisperse FePt magnetic nanocrystals

Cited by 106 publications

References 35 publications

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

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

Simple top-down preparation of magnetic Bi_0.9Gd_0.1Fe_1−xTi_xO₃nanoparticles by ultrasonication of multiferroic bulk material

On the Possibility to Control an Atom Motion in a FCC Iron Nanocluster

Contact Info

Product

Resources

About

Shapes, multiple twins and surface structures of monodisperse FePt magnetic nanocrystals

Cited by 106 publications

References 35 publications

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

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

Simple top-down preparation of magnetic Bi0.9Gd0.1Fe1−xTixO3nanoparticles by ultrasonication of multiferroic bulk material

On the Possibility to Control an Atom Motion in a FCC Iron Nanocluster

Contact Info

Product

Resources

About

Simple top-down preparation of magnetic Bi_0.9Gd_0.1Fe_1−xTi_xO₃nanoparticles by ultrasonication of multiferroic bulk material