Passive Layer Formation at Ferroelectric PbTiO3/Pt Interfaces Studied by EELS

2005 ◽  
Vol 875 ◽  
Author(s):  
S. J. Welz ◽  
L. F. Fu ◽  
R. Erni ◽  
M. Kurasawa ◽  
P. C. McIntyre ◽  
...  
Keyword(s):  
Degradation Process ◽  
Amorphous Layer ◽  
Passive Layer ◽  
Film Material ◽  
Pt Electrode ◽  
Ferroelectric Capacitor ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Z Contrast ◽  
Electron Energy Loss

AbstractPolarization fatigue with repeated electric cycles in ferroelectric thin films is a major degradation problem in ferroelectric nonvolatile memories. However, the origin of this phenomenon is still not properly understood. The fatigue mechanism of a ferroelectric perovskite in a multilayer ferroelectric PbTiO3 thin film material has been investigated here using scanning transmission electron microscopy (STEM). Z-contrast images of the interfaces show that the ferroelectric PbTiO3 layer has partly decomposed into a single crystal PbTiO3 layer and an amorphous layer. Nanometer-sized precipitates are present near the Pt electrode. Electron energy-loss spectroscopy (EELS) analysis reveals that the amorphous layer is a Ti-rich phase between TiO2 and PbTiO3. The precipitates are determined to be a Pt-Pb rich crystalline phase. It is suggested that the formation of the structure-distorted intermediate layer and precipitates may be associated with the ferroelectric degradation process by acting as a passive layer in a ferroelectric capacitor. In addition, the formation of the Pt-Pb rich precipitates may cause an interruption of the consistent Pt electrode, which may result in failure of the device.

Analysis of Nanometer Sized Pyrogenic Particles by Scanning Transmission Electron Microscopy

1995 ◽  
Vol 53 ◽  
pp. 218-219
Author(s):  
DJ Wallis ◽  
ND Browning ◽  
CM Megaridis
Keyword(s):  
Operating Conditions ◽  
Atomic Scale ◽  
Contrast Imaging ◽  
Chemical Mechanisms ◽  
Transmission Electron ◽  
Angle Scattering ◽  
Scanning Transmission ◽  
Z Contrast ◽  
Physical And Chemical ◽  
Electron Energy Loss

Iron is a ubiquitous element on the earth's surface, and is thus involved in most naturally occurring fires. Iron organometalic compounds have also been known to suppress carbonaceous soot emissions under certain operating conditions of practical combustors. In order to unravel the physical and chemical mechanisms of influence, of iron on the emission of carbonaceous pyrogenic particles, finescale characterization techniques need to be implemented.The combined techniques of Z-contrast imaging and electron energy loss spectroscopy (EELS) in a VG HB-501 dedicated STEM are ideally suited to study such a system. The sensitivity of the Z-contrast imaging technique to high-Z materials makes it ideal for location of the iron particles within the much lower atomic number matrix. As only the high-angle scattering is used in the image formation, EELS can be performed simultaneously from a position defined in the image. This accurate positioning of the probe by the Z-contrast image permits both compositional and bonding information to be obtained with a spatial resolution approaching the atomic scale.

Direct Observation of Intercalant and Catalyst Particle in Single Wall Carbon Nanotubes

1999 ◽  
Vol 593 ◽  
Author(s):  
X. Fan ◽  
E. C. Dickey ◽  
P. Eklund ◽  
K. Williams ◽  
L. Grigorian ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Catalyst Particle ◽  
Single Wall Carbon Nanotubes ◽  
Contrast Imaging ◽  
Single Wall Carbon ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Dopant Atoms ◽  
Z Contrast ◽  
Electron Energy Loss

ABSTRACTThe Z-contrast scanning transmission electron microscopy (STEM) imaging technique has been used to study dopant atoms and catalyst particles in single wall carbon nanotubes (SWNT). Iodine and bromine have been doped respectively in arc-grown SWNTs. We have directly observed the dopant sites and distributions. Both dopants appear to be incorporated linearly within the SWNT bundles. SWNT were also grown by pulsed laser ablation with mixed Ni and Co catalyst, and the size and distribution of catalytic particles was studied. By using Z-contrast imaging, we found that the size distribution of the catalyst particles varied over a large range, but even the smallest were larger than the diameter of an individual SWNT. Furthermore, electron energy loss spectroscopy (EELS) is used to determine the composition of individual nanocatalyst particles, and were found to consist of a uniform alloy of Co and Ni.

SiO2 Formation at the Aluminum Oxide/Si(100) Interface

2002 ◽  
Vol 747 ◽  
Author(s):  
A. Roy Chowdhuri ◽  
C. G. Takoudis ◽  
R. F. Klie ◽  
N. D. Browning
Keyword(s):  
Electron Microscope ◽  
Aluminum Oxide ◽  
Energy Loss ◽  
Electron Energy ◽  
Transmission Electron Microscope ◽  
Scanning Transmission Electron Microscope ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Z Contrast ◽  
Electron Energy Loss

ABSTRACTThin films of aluminum oxide were deposited on clean Si(100) substrates using trimethylaluminum and oxygen at 300°C. Infrared spectroscopic and x-ray photoelectron spectroscopic analyses of these films showed no aluminum silicate or SiO2 phase formation at the film/substrate interface. The O/Al ratio in the as deposited film was found to be higher than that in stoichiometric Al2O3. On annealing the as deposited samples in Ar at higher temperatures, a peak due to the transverse optical phonon for the Si-O-Si stretching mode appeared in the infrared spectra. A combination of Z-contrast imaging and electron energy loss spectroscopy in the scanning transmission electron microscope confirmed that the annealed samples developed a layer of silicon dioxide at the aluminum oxide-Si interface. Z-contrast images and electron energy loss spectra, obtained while heating the sample inside the scanning transmission electron microscope were used to follow the interfacial SiO2 formation.

Interfacial Disorder of Graphene Grown at High Temperatures on 4H-SiC(000-1)

2016 ◽  
Vol 858 ◽  
pp. 1129-1132
Author(s):  
Filippo Giannazzo ◽  
Giuseppe Nicotra ◽  
Ioannis Deretzis ◽  
Aurora Piazza ◽  
Gabriele Fisichella ◽  
...  
Keyword(s):  
High Temperatures ◽  
Amorphous Layer ◽  
Force Microscopy ◽  
Annealing Conditions ◽  
Atomic Force ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Disordered Layer ◽  
Electron Energy Loss

This paper presents an investigation of the morphological and structural properties of graphene (Gr) grown on SiC(000-1) by thermal treatments at high temperatures (from 1850 to 1950 °C) in Ar at atmospheric pressure. Atomic force microscopy and micro-Raman spectroscopy showed that the grown Gr films are laterally inhomogeneous in the number of layers, and that regions with different stacking-type (coupled or decoupled Gr films) can coexist in the same sample. Scanning transmission electron microscopy and electron energy loss spectroscopy shoed that a nm-thick C-Si-O amorphous layer is present at the interface between Gr and SiC. Basing on these structural results, the mechanisms of Gr growth on the C-face of SiC under these annealing conditions and the role of this disordered layer in the suppression of epitaxy between Gr and the substrate have been discussed.

Atomic Structure of La067Ca0.33MnO3 Thin Films on LaAlO3

2000 ◽  
Vol 6 (S2) ◽  
pp. 402-403
Author(s):  
H-J. Gao ◽  
C.L. Chen ◽  
X. Fan ◽  
M. Kim ◽  
S.Y. Chen ◽  
...  
Keyword(s):  
Thin Films ◽  
Atomic Structure ◽  
Perovskite Manganites ◽  
X Ray Diffraction ◽  
Transmission Microscopy ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Film Substrate ◽  
Z Contrast ◽  
Electron Energy Loss

Thin films of doped perovskite manganites of the type R1-X AxMnO3-y are currently become the focus of intense theoretical and experimental research due to their promising technological implications. However, the microstructure of the film and the interface structure at the atomic level remains unclear. In this report, we will present the atomic structure of the film/substrate interface and the microstructure of the film using a combination of transmission electron microscopy (TEM), Z-contrast scanning transmission microscopy (STEM), and electron energy loss spectroscopy (EELS).The La0.67Ca0.33MnO3 (LCMO) samples were grown on (001) LaA1O3 (LAO) using pulsed laser deposition. X-ray diffraction indicated the films to be oriented with the [001] directions parallel to the <001> directions of the pseudo-cubic perovskite LAO. Rocking curve measurements using the (002) reflection from the film indicated a full width half maximum of less than 0.3°. A Philips EM-400 electron microscope at 100 kV and a VG HB603 STEM at 300 kV were employed for sample analysis.

Redox-Couple Investigations in Si-Doped Li-Rich Cathode Materials

2021 ◽  
Author(s):  
Leah Nation ◽  
Yan Wu ◽  
Xiaoming Liu ◽  
Miaofang Chi ◽  
Yuqin Wu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electrochemical Behavior ◽  
Scanning Transmission Electron Microscopy ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Si Doped ◽  
Z Contrast ◽  
Electron Energy Loss

In this investigation, the improved electrochemical behavior in Si-doped Li-rich cathodes is studied with scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). Z-contrast images show a layered...

High Spatial Resolution Compositional Analysis at Interfaces

1980 ◽  
Vol 38 ◽  
pp. 356-359
Author(s):  
John B. Vander Sande ◽  
Thomas F. Kelly ◽  
Douglas Imeson
Keyword(s):  
Electron Microscope ◽  
High Spatial Resolution ◽  
Compositional Analysis ◽  
Scanning Transmission Electron Microscope ◽  
Thin Specimen ◽  
X Ray ◽  
Volume Of Interest ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Energy Loss

In the scanning transmission electron microscope (STEM) a fine probe of electrons is scanned across the thin specimen, or the probe is stationarily placed on a volume of interest, and various products of the electron-specimen interaction are then collected and used for image formation or microanalysis. The microanalysis modes usually employed in STEM include, but are not restricted to, energy dispersive X-ray analysis, electron energy loss spectroscopy, and microdiffraction.

Synthesis and Structural Characterization of Ferromagnetic Au/Co Nanoparticles

2014 ◽  
Vol 1708 ◽  
Author(s):  
Nabraj Bhattarai ◽  
Subarna Khanal ◽  
Daniel Bahena ◽  
Robert L. Whetten ◽  
Miguel Jose-Yacaman
Keyword(s):  
Quantum Interference ◽  
Magnetic Measurements ◽  
Ferromagnetic Behavior ◽  
Contrast Imaging ◽  
Uniform Size ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Co Nanoparticles ◽  
Z Contrast

ABSTRACTThe synthesis of bimetallic magnetic nanoparticles is very challenging because of the agglomeration and non-uniform size. In this paper, we present the synthesis of monodispersed 3-5 nm sized thiolated bimetallic alloyed Au/Co nanoparticles with decahedral and icosahedral shape, their characterization using Cs-corrected scanning transmission electron microscopy (STEM) and magnetic measurements using superconducting quantum interference device (SQUID) magnetometer. The Z-contrast imaging and energy dispersive X-ray spectroscopy (EDS) mapping showed an inhomogeneous alloying with minor segregation between Au and Co at nanoscale and the SQUID measurement exhibited the ferromagnetic behavior.

Variation of the ELNES Under Channeling Conditions

2001 ◽  
Vol 7 (S2) ◽  
pp. 342-343
Author(s):  
S. Köstlmeier ◽  
S. Nufer ◽  
T. Gemming ◽  
M. Rühle
Keyword(s):  
Incident Beam ◽  
Scanning Transmission Electron Microscope ◽  
Orientation Dependence ◽  
Beam Direction ◽  
Rotation Axes ◽  
Transmission Electron ◽  
Anisotropic Solid ◽  
Scanning Transmission ◽  
Electron Energy Loss ◽  
Acceleration Voltage

The orientation dependence of the fine structure of the Al L1 and L2,3 electron energy loss (EELS) edges in (α-Al2O3 has been investigated by measurements with a dedicated scanning transmission electron microscope (VG HB501 STEM, 100 keV acceleration voltage). α-Al2O3 is an anisotropic solid with a complicated alternating stacking sequence of fee Al and hcp O planes along the [0001] direction [1]. This distingiushes the [0001] direction crystallographically, as the highest-order three-fold rotation axes (C3) of the trigonal crystal structure are parallel to [0001], whereas all other symmetry elements are of lower order. Group theory predicts, that more stringent symmetry selection rules apply when electronic transitions are excited by irradiation parallel to the low-index [0001] zone axis than by irradiation along any other arbitrary direction.Yet, even for a low-energy EELS edge (θE = 0.4 mrad) both scattering parallel and perpendicular to the incident beam direction are likely.

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