Atomic structure imaging of L1-type FePd nanoparticles by spherical aberration corrected high-resolution transmission electron microscopy

Abstract

Articles you may be interested inThree-dimensional shapes and distribution of FePd nanoparticles observed by electron tomography using highangle annular dark-field scanning transmission electron microscopyThe atomic structure of FePd nanoparticles has been studied by spherical aberration ͑C s ͒ corrected high-resolution transmission electron microscopy. The periodic arrangement of atoms arising from chemical order is clearly seen as bright contrast due to the small negative value of corrected C s . The amount of optimal defocus ͑Scherzer defocus͒ is markedly reduced by the small C s value. The interface between crystalline particles and the amorphous matrix can also be observed, free of imaging artifacts, at a small defocus value. The reconstructed phase image directly shows the projected potential distribution within the specimen and reveals the elemental differences due to chemical order. The clear-cut long-range order is lost when particle size is smaller than about 5 nm, at which locally ordered mixed-phase particles begin to dominate.

Three-dimensional shapes and distribution of FePd nanoparticles observed by electron tomography using high-angle annular dark-field scanning transmission electron microscopy

“…FePd nanoparticles were fabricated by sequential electron beam deposition of Pd and Fe onto a NaCl͑001͒ substrate at 673 K. 3,4 After deposition of Fe, an amorphous Al 2 O 3 thin film was deposited to protect the particles from oxidation. The as-deposited specimen film was then removed from the NaCl substrate by immersing the substrate into distilled water, and was mounted onto conventional copper grids for STEM observation.…”

“…The as-deposited specimen film was then removed from the NaCl substrate by immersing the substrate into distilled water, and was mounted onto conventional copper grids for STEM observation. [3][4][5]23 Z-contrast STEM images were obtained using an FEI Titan 80-300 ͑S͒TEM operating at 300 kV with a field emission gun. 23 The mean cooling rate after the annealing was about 10 K/min.…”

“…[3][4][5] On the other hand, high-areal density packing of nanoparticles and control of magnetostatic interaction among nanoparticles are considered as the next step to realize ultrahigh density magnetic storage media. FePd alloy nanoparticles with the L1 0 -type ordered structure is one of the candidate materials suitable for the ultrahigh density magnetic storage media.…”

Magnetic Properties of FePd Nanoparticles Prepared by Sonoelectrodeposition

“…[1][2][3][4][5][6][7][8][9][10][11] Ordered face-centered tetragonal (fct) L1 0 FePd materials are normally obtained from disordered face-centered cubic (fcc) materials via the order-disorder transition. Several approaches to the preparation of FePd nanoparticles have been reported including epitaxial growth by electron beam deposition, 4-6 chemical synthesis 7,8,11 (which is modified from the FePt nanoparticles synthesis method by Sun et al 12 ), modified polyol process, 9 and microwave irradiation 2 .…”

Identification of magnetic properties of few nm sized FePt crystalline particles by characterizing the intrinsic atom order using aberration corrected S/TEM

“…the chemical degree of order is S ¼0.5 have been categorized either on the side of pure fct particles or of pure fcc particles. FePt particles [20] and FePd particles [20][21][22] were studied by Sato and co-workers by aberration corrected TEM and nanobeam diffraction. In these works ordering effects of the particles were investigated showing a size-dependent ordering as well lattice parameter changes because of composition changes.…”