Fabrication and electron holography characterization of FePt alloy nanorods

2005 ◽  
Vol 87 (22) ◽  
pp. 223109 ◽  
Author(s):  
R. C. Che ◽  
M. Takeguchi ◽  
M. Shimojo ◽  
W. Zhang ◽  
K. Furuya
Keyword(s):  
Electron Holography ◽  
Fept Alloy

Characterization of JEOL 3000f TEM Equipped for Electron Holography

2000 ◽  
Vol 6 (S2) ◽  
pp. 228-229
Author(s):  
M. A. Schofield ◽  
Y. Zhu
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Design Of Experiment ◽  
Electron Holography ◽  
Fringe Spacing ◽  
Interference Fringes ◽  
Transmission Electron ◽  
Careful Design

Quantitative off-axis electron holography in a transmission electron microscope (TEM) requires careful design of experiment specific to instrumental characteristics. For example, the spatial resolution desired for a particular holography experiment imposes requirements on the spacing of the interference fringes to be recorded. This fringe spacing depends upon the geometric configuration of the TEM/electron biprism system, which is experimentally fixed, but also upon the voltage applied to the biprism wire of the holography unit, which is experimentally adjustable. Hence, knowledge of the holographic interference fringe spacing as a function of applied voltage to the electron biprism is essential to the design of a specific holography experiment. Furthermore, additional instrumental parameters, such as the coherence and virtual size of the electron source, for example, affect the quality of recorded holograms through their effect on the contrast of the holographic fringes.

Growth and Characterization of Fept Compound thin Films

1995 ◽  
Vol 384 ◽  
Author(s):  
M.R. Visokay ◽  
R. Sinclair
Keyword(s):  
Epitaxial Films ◽  
Orientation Dependence ◽  
Kerr Rotation ◽  
Fept Alloy ◽  
Disordered Alloys ◽  
Disordered Films ◽  
Out Of Plane ◽  
Temperature Deposition ◽  
Fcc Alloys

ABSTRACTFePt alloy films were deposited at 50 and 49°C onto amorphous SiO2 and single crystal [001] MgO and [0001] Al2O3 using DC magnetron cosputtering, resulting in polycrystalline and [001] and [111] epitaxial films, respectively. High temperature deposition resulted in ordered films with the tetragonal Ll structure and out-of-plane magnetic easy axes while low temperature deposition yielded chemically disordered fcc alloys with in-plane easy axes. Significant modification of the magneto-optic Kerr spectrum is observed for ordered relative to disordered alloys for all orientations. The Kerr rotation has a strong orientation dependence for the ordered, but not disordered films.

scholarly journals Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles

2010 ◽  
Vol 1 ◽  
pp. 24-47 ◽  
Author(s):  
Ulf Wiedwald ◽  
Luyang Han ◽  
Johannes Biskupek ◽  
Ute Kaiser ◽  
Paul Ziemann
Keyword(s):  
Magnetic Anisotropy ◽  
Reverse Micelles ◽  
Metallic Nanoparticles ◽  
Particle Diameter ◽  
Fept Nanoparticles ◽  
Fept Alloy ◽  
Imperfect Crystal ◽  
Co Nanoparticles

Monatomic (Fe, Co) and bimetallic (FePt and CoPt) nanoparticles were prepared by exploiting the self-organization of precursor loaded reverse micelles. Achievements and limitations of the preparation approach are critically discussed. We show that self-assembled metallic nanoparticles can be prepared with diameters d = 2–12 nm and interparticle distances D = 20–140 nm on various substrates. Structural, electronic and magnetic properties of the particle arrays were characterized by several techniques to give a comprehensive view of the high quality of the method. For Co nanoparticles, it is demonstrated that magnetostatic interactions can be neglected for distances which are at least 6 times larger than the particle diameter. Focus is placed on FePt alloy nanoparticles which show a huge magnetic anisotropy in the L10 phase, however, this is still less by a factor of 3–4 when compared to the anisotropy of the bulk counterpart. A similar observation was also found for CoPt nanoparticles (NPs). These results are related to imperfect crystal structures as revealed by HRTEM as well as to compositional distributions of the prepared particles. Interestingly, the results demonstrate that the averaged effective magnetic anisotropy of FePt nanoparticles does not strongly depend on size. Consequently, magnetization stability should scale linearly with the volume of the NPs and give rise to a critical value for stability at ambient temperature. Indeed, for diameters above 6 nm such stability is observed for the current FePt and CoPt NPs. Finally, the long-term conservation of nanoparticles by Au photoseeding is presented.

Nanoscale characterization of Pd/TiO2 catalysts and Ag/TiO2 catalysts by electron holography

2005 ◽  
Vol 900 ◽  
Author(s):  
Satoshi Ichikawa ◽  
Tomoki Akita ◽  
Kazuyuki Okazaki ◽  
Koji Tanaka ◽  
Masanori Kohyama
Keyword(s):  
Catalytic Properties ◽  
Nano Particles ◽  
Electron Holography ◽  
Noble Metal Catalysts ◽  
Ag Particles ◽  
Nanoscale Characterization ◽  
The Mean ◽  
Ag Particle ◽  
Experimental Values

ABSTRACTCatalytic properties of noble metal catalysts are often caused by their nanostructures and the interaction between nano particles and oxides supports. We examine the mean inner potential of Pd particles in Pd/TiO2 catalyst and Ag particles in Ag/TiO2 catalysts using electron holography and HRTEM. And we compare the results of the Pd/TiO2 and Ag/TiO2 systems with our previous results of the Au/TiO2 and Pt/TiO2 systems. In the case of the Pd/TiO2 catalysts, when the size of Pd particle is smaller than 5nm, the mean inner potential of Pd changes to be higher than the calculated value of the mean inner potential which is thought to be higher than the experimental values of bulk Pd by 3-5V. The mean inner potential of Pd becomes to increase gradually as the size of the Pd particle decreases. The rate of the increment in the mean inner potential of Pd is lower than that of Au/TiO2 catalysts and Pt/TiO2 catalysts. On the other hand, in the case of Ag/TiO2 catalysts, the mean inner potential of Ag does not increase though the size of the Ag particle decreases to under 2nm.

scholarly journals Characterization of Semiconductor Materials Using Electron Holography

2017 ◽  
Vol 23 (S1) ◽  
pp. 1404-1405
Author(s):  
Lin Zhou ◽  
Zhaofeng Gan ◽  
Myung-Geun Han ◽  
David J. Smith ◽  
Martha R. McCartney
Keyword(s):  
Semiconductor Materials ◽  
Electron Holography

Electron Holography, a Versatile Tool for Characterization of Materials: Fluoroapatite-Gelatine-Composites, SiC and SiO2

2005 ◽  
Vol 631 (6-7) ◽  
pp. 983-992 ◽  
Author(s):  
Paul Simon ◽  
Hannes Lichte ◽  
Damian M�nter ◽  
Wladimir Reschetilowski ◽  
Anibal Valera ◽  
...  
Keyword(s):  
Electron Holography ◽  
Versatile Tool ◽  
Characterization Of Materials

Electron Holographic Characterization of Nano-Hetero Interface Effect in Gold Catalysts

2004 ◽  
Vol 839 ◽  
Author(s):  
S. Ichikawa ◽  
T. Akita ◽  
K. Okazaki ◽  
K. Tanaka ◽  
M. Kohyama
Keyword(s):  
Gold Particle ◽  
Size Dependence ◽  
Critical Size ◽  
High Resolution Electron Microscopy ◽  
The Other ◽  
Electron Holography ◽  
Bulk State ◽  
Resolution Electron ◽  
The Mean

ABSTRACTWe investigated the atomic structure near the interface and the size dependence of the mean inner potential of gold in Au/TiO2 catalysts prepared by the deposition precipitation (DP) method and the vacuum evaporation (VE) method using high resolution electron microscopy (HREM) and electron holography. The TiO2 supports prepared by DP method and VE method are considered to have oxygen-rich surfaces and titanium-rich surfaces respectively. In case of the Au/TiO2 catalyst prepared by DP method, the mean inner potential of gold increased depending on the size of the particle. When the size of the gold particle is over 5nm, the mean inner potential of gold was the same as that of bulk Au. When the size is below 5nm, the mean inner potential became to increase. It increases suddenly over 40V, particularly in case of below 2nm. It indicates that the electronic state of gold on TiO2 changes from that of bulk state as the size decreases. On the other hand, the mean inner potential of gold in Au/TiO2 catalysts prepared by VE method also increased as the size decreased, but the behavior of the size dependence is different from that of DP method. The critical size of the mean inner potential change is around 3nm. The size of the gold particle was below 3nm, the mean inner potential of gold increased gradually. The mean inner potential of VE method is less than that of DP method with the same particle size in spite of the size below 3nm. The stoichiometry at the interface between Au and TiO2 should be one of the dominant reasons for the behavior difference of the size dependence of the mean inner potential between the preparations.

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