Effects of Substrates on the Self-Assembling of FePt Nanocrystals

ABSTRACTFe48Pt52 nanoparticles were synthesized by the simultaneous chemical reduction of platinum acetylacetonate and thermal decomposition of iron pentacarbonyl. As-prepared the particles were spherical with an average diameter of 3 nm and a polydispersity of less than 5%. The particles were superparamagnetic and had a fcc structure. Highly ordered self-assembled supercrystals of particles were formed in TEM grids by deposition from dispersions in hydrocarbon solvents. Nanoparticles deposited on amorphous carbon-coated and SiO2-coated Cu grids tend to assemble into small domains of hexagonal arrays. Larger domains of hexagonal arrays formed on Si3N4 membrane TEM grids. For thin multilayers, the FePt nanoparticles tends to assemble into hexagonal close-packed lattices (ABABAB stacking). For the thicker multilayers, ABCABC stacking was observed. Small angle X-ray reflectivity of the particles on a Si (100) substrate show highly ordered multiplanar structure with d-spacing of 6.2 nm. The coercivity of self-assembled FePt films strongly depended on the annealing temperature. After annealing at 700°C for 30 minutes, the particles transformed from FCC to “FCT” phase and the coercivity of film increased up to 11570 Oe. However, the particle size increased to 16 nm due to sintering.

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Synthesis and Self-Assembly of Films Containing FeCoPt Nanoparticles

MRS Proceedings ◽

10.1557/proc-674-u4.7 ◽

2001 ◽

Vol 674 ◽

Cited By ~ 1

Author(s):

Min Chen ◽

David E. Nikles

Keyword(s):

Self Assembly ◽

Annealing Temperature ◽

Chemical Reduction ◽

Average Diameter ◽

Iron Pentacarbonyl ◽

Face Centered Cubic ◽

Oxidized Iron ◽

Carbon Coated ◽

Face Centered ◽

Cobalt Acetylacetonate

ABSTRACTFe49Co7Pt44 and Fe40Co17Pt43nanoparticles were synthesized by simultaneous chemical reduction of platinum acetylacetonate and cobalt acetylacetonate and thermal decomposition of iron pentacarbonyl. As-prepared the particles had a disordered face-centered cubic lattice with an average diameter of 3.2 nm and were superparamagnetic. These particles were well dispersed in a 50/50 mixture of hexane and octane. The particles self-assembled into ordered superlattices when deposited onto carbon coated Cu TEM grids or onto single crystal Si (100) substrates. After vacuum annealing (from 500°C to 700 °C), the particles transformed to the tetragonal phase. The coercivity of the film strongly depended on the composition and annealing temperature. For the Fe49Co7Pt44film, coercivity of 8700 Oe and a squareness of 0.75 after annealing at 700 °C for 30 minutes. XPS shows existance of oxidized iron and cobalt on the surface of film.

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Synthesis, Self-assembly and Magnetic Properties of FePtCu Nanoparticle Arrays

MRS Proceedings ◽

10.1557/proc-739-h7.40 ◽

2002 ◽

Vol 739 ◽

Author(s):

Xiangcheng Sun ◽

S. S. Kang ◽

J. W. Harrell ◽

David E. Nikles ◽

Z. R. Dai ◽

...

Keyword(s):

Self Assembly ◽

Magnetic Hysteresis ◽

Average Diameter ◽

Iron Pentacarbonyl ◽

Close Packing ◽

Three Dimensions ◽

Second Phase ◽

Hard Component ◽

Extra Peak ◽

Self Assembled

ABSTRACTFePtCu nanoparticles with varying composition were synthesized by chemical solution-phase reduction of platinum and copper reagents and thermal decomposition of iron pentacarbonyl in the presence of oleic acid and oleyl amine stabilizers. As prepared the particles had fcc structure with an average diameter of 3.5 nm and were superparamagnetic. The particles were well dispersed in hydrocarbon solvents and could be self-assembled into two or three dimensions particles arrays with a variety of close-packing arrangements. Heat-treatment of the self-assembled films at temperatures above 550°C transformed the particles from the fcc to the L10 phase, giving in-plane coercivities as high as 9000 Oe. X-ray diffraction revealed that the Cu remained in the annealed FePtCu films and the presence of an extra peak, indicated a second phase was present. Consistent with one or more phases, the magnetic hysteresis curves could be decomposed into a hard component (Hc > 5,000 Oe) and a soft component (Hc < 2,000 Oe). Unlike our earlier results for Ag in FePt, adding Cu to FePt did not lower the temperature required for phase transformation from the fcc to the fct L10 phase.

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Structure of Self-assembled Magnetic FePtCu Nanoparticles Arrays

MRS Proceedings ◽

10.1557/proc-775-p9.8 ◽

2003 ◽

Vol 775 ◽

Author(s):

Xiangcheng Sun ◽

J.W. Harrell ◽

D. E. Nikles ◽

K. Sun ◽

L. M. Wang ◽

...

Keyword(s):

Average Diameter ◽

Iron Pentacarbonyl ◽

Particle Packing ◽

Three Dimensions ◽

Face Centered Cubic ◽

Oleyl Amine ◽

Organic Surfactant ◽

Self Assembled ◽

Face Centered ◽

Organic Capping

AbstractIn this study, a series of FexPtyCu100-x-y nanoparticles were chemically synthesized by solution-phase reduction of platinum and copper reagents and thermal decomposition of iron pentacarbonyl in the presence of stabilizers oleic acid and oleyl amine. As-prepared particles had a chemically disordered face-centered cubic (fcc) lattice with an average diameter of 3.5 nm. The particle size, and the corresponding size distribution were controlled by varying the organic surfactant (oleic acids, etc.), its concentration, and the reaction temperature. These particles were well dispersed in hydrocarbon solvents and self-assembled into two or three dimensions particles arrays with a variety of closepacking arrangements. Domain of monolayers, bilayers and multilayers of particles arrays were frequently detected in TEM specimens. Both cubic close-packed (ccp) and honeycomb arrays were also uniquely observed. It was also demonstrated that the controlled organic surfactant layer (organic capping) play a crucial role in determining assembly dimensions and symmetry as well as particle packing arrays.

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Hierarchical nanostructures self-assembled from δ-MnO2 ultrathin nanosheets and Mn3O4 octahedrons for efficient room-temperature HCHO oxidation

New Journal of Chemistry ◽

10.1039/d0nj05515h ◽

2021 ◽

Author(s):

Lifang Qi ◽

Yao Le ◽

Chao Wang ◽

Rui Lei ◽

Tian Wu

Keyword(s):

Room Temperature ◽

Hierarchical Nanostructures ◽

Low Level ◽

Ultrathin Nanosheets ◽

Self Assembling ◽

Formaldehyde Oxidation ◽

Self Assembled

Self-assembling ultrathin active δ-MnO2 nanosheets and Mn3O4 octahedrons into hierarchical texture enhances room-temperature formaldehyde oxidation at a low-level of Pt.

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Superhydrophilic Coating of Pine Wood by Plasma Functionalization of Self-Assembled Polystyrene Spheres

Coatings ◽

10.3390/coatings11020114 ◽

2021 ◽

Vol 11 (2) ◽

pp. 114

Author(s):

Sebastian Dahle ◽

John Meuthen ◽

René Gustus ◽

Alexandra Prowald ◽

Wolfgang Viöl ◽

...

Keyword(s):

Dip Coating ◽

Face Centered Cubic ◽

Wood Substrate ◽

Polystyrene Spheres ◽

Pine Wood ◽

Self Assembling ◽

Monodisperse Polystyrene ◽

Self Assembled ◽

Face Centered ◽

Plasma Functionalization

Self-assembling films typically used for colloidal lithography have been applied to pine wood substrates to change the surface wettability. Therefore, monodisperse polystyrene (PS) spheres have been deposited onto a rough pine wood substrate via dip coating. The resulting PS sphere film resembled a polycrystalline face centered cubic (FCC)-like structure with typical domain sizes of 5–15 single spheres. This self-assembled coating was further functionalized via an O2 plasma. This plasma treatment strongly influenced the particle sizes in the outermost layer, and hydroxyl as well as carbonyl groups were introduced to the PS spheres’ surfaces, thus generating a superhydrophilic behavior.

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Three-Dimensional Hexagonal Close-Packed Superlattices of Passivated Ag Nanocrystals

Microscopy and Microanalysis ◽

10.1017/s1431927600009041 ◽

1997 ◽

Vol 3 (S2) ◽

pp. 431-432

Author(s):

S. A. Harfenist ◽

Z. L. Wang ◽

R. L. Whetten ◽

I. Vezmar ◽

M. M. Alvarez ◽

...

Keyword(s):

Carbon Film ◽

Three Dimensional ◽

Structure Characterization ◽

Self Assembled Monolayers ◽

Hexagonal Close Packed ◽

Self Assembling ◽

Transmission Electron ◽

Assembled Monolayers ◽

High Resolution Tem ◽

Nanocrystal Superlattices

Silver nanocrystals passivated by dodecanethiol self-assembled monolayers were produced using an aerosol technique described in detail elsewhere [1]. Self-assembling passivated nanocrystal-superlattices (NCS's) involve self-organization into monolayers, thin films, and superlattices of size-selected nanoclusters encapsulated in a protective compact coating [2,3,4,5,6,7]. We report the preparation and structure characterization of three-dimensional (3-D) hexagonal close-packed Ag nanocrystal supercrystals from Ag nanocrystals of ˜4.5 nm in diameters. The crystallography of the superlattice and atomic core lattices were determined using transmission electron microscopy (TEM) and high-resolution TEM.SEM was used to image the nanocrystal superlattices formed on an amorphous carbon film of an TEM specimen grid (fig. la). The superlattice films show well shaped, sharply faceted, triangular shaped sheets. Figure lb depicts numerous Ag nanocrystal aggregates uniformly distributed over the imaging region. Inset in this figure is an enlargement of the boxed region at the edge of a supercrystal typifying the ordered nanocrystal packing.

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Carbon-Coated Self-Assembled Ultrathin T-Nb2O5 Nanosheets for High-Rate Lithium-Ion Storage with Superior Cycling Stability

ACS Applied Energy Materials ◽

10.1021/acsaem.0c02180 ◽

2020 ◽

Vol 3 (12) ◽

pp. 12037-12045

Author(s):

Yang Li ◽

Yan Wang ◽

Guirong Cui ◽

Tianyu Zhu ◽

Jianfang Zhang ◽

...

Keyword(s):

Lithium Ion ◽

Cycling Stability ◽

High Rate ◽

Ion Storage ◽

Carbon Coated ◽

Self Assembled ◽

Superior Cycling Stability

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Synthesis of cobalt nanowires in aqueous solution under an external magnetic field

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.7.91 ◽

2016 ◽

Vol 7 ◽

pp. 990-994 ◽

Cited By ~ 6

Author(s):

Xiaoyu Li ◽

Lijuan Sun ◽

Hu Wang ◽

Kenan Xie ◽

Qin Long ◽

...

Keyword(s):

Magnetic Field ◽

Aqueous Solution ◽

External Magnetic Field ◽

Room Temperature ◽

Magnetic Measurements ◽

Chemical Reduction ◽

Average Diameter ◽

Firm Structure ◽

Cobalt Nanowires ◽

First Time

In contrast to the majority of related experiments, which are carried out in organic solvents at high temperatures and pressures, cobalt nanowires were synthesized by chemical reduction in aqueous solution with the assistance of polyvinylpyrrolidone (PVP) as surfactant under moderate conditions for the first time, while an external magnetic field of 40 mT was applied. Uniform linear cobalt nanowires with relatively smooth surfaces and firm structure were obtained and possessed an average diameter of about 100 nm with a coating layer of PVP. By comparison, the external magnetic field and PVP were proven to have a crucial influence on the morphology and the size of the synthesized cobalt nanowires. The prepared cobalt nanowires are crystalline and mainly consist of cobalt as well as a small amount of platinum. Magnetic measurements showed that the resultant cobalt nanowires were ferromagnetic at room temperature. The saturation magnetization (M s) and the coercivity (H c) were 112.00 emu/g and 352.87 Oe, respectively.

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Self-assembled nano-aggregates of fluorinases demonstrate enhanced enzymatic activity, thermostability and reusability

Biomaterials Science ◽

10.1039/c9bm00402e ◽

2020 ◽

Vol 8 (2) ◽

pp. 648-656

Author(s):

Chunhao Tu ◽

Jin Zhou ◽

Lei Peng ◽

Shuli Man ◽

Long Ma

Keyword(s):

Aqueous Solution ◽

Enzyme Activity ◽

Enzymatic Activity ◽

Self Assembling ◽

Self Assembled

Three SAP (self-assembling peptide)-tagged fluorinases (FLAs) are successfully prepared. All three SAP-tagged FLAs bear enzymatic activity and they form nano-sized particles in aqueous solution. One of them displays improved enzyme activity, thermostability and reusability.

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