Investigation of phase separation in InGaN alloys by plasmon loss spectroscopy in a TEM

MRS Advances ◽  
2016 ◽  
Vol 1 (40) ◽  
pp. 2749-2756 ◽  
Author(s):  
Xiaoyi Wang ◽  
Marie-Pierre Chauvat ◽  
Pierre Ruterana ◽  
Thomas Walther
Keyword(s):  
Phase Separation ◽  
Core Loss ◽  
Radiation Sensitivity ◽  
Indium Content ◽  
Peak Position ◽  
Low Loss ◽  
Plasmon Peak ◽  
Core Losses ◽  
Plasmon Loss ◽  
Binary Compounds

ABSTRACTPhase separation of InxGa1-xN alloys into Ga-rich and In-rich regions was observed by a number of research groups for samples grown with high indium content, x. Due to the radiation sensitivity of InGaN to beam damage by fast electrons, high-resolution imaging in transmission electron microscopy (TEM) or core-loss electron energy-loss spectroscopy (EELS) may lead to erroneous results. Low-loss EELS can yield spectra of the plasmon loss regions at much lower electron fluxes. Unfortunately, due to their delayed edge onset, the low energetic core losses of Ga and In partially overlap with the plasmon peaks, all of which shift with indium content.Here we demonstrate a method to quantify phase separation in InGaN thin films from the low-loss region in EELS by simultaneously fitting both plasmon and core losses over the energy range of 13-30eV. Phase separation is shown to lead to a broadening of the plasmon peak and the overlapping core losses, resulting in an unreliable determination of the indium concentration from analyzing the plasmon peak position alone if phase separation is present. For x=0.3 and x=0.59, the relative contributions of the binary compounds are negligibly small and indicate random alloys. For xnom.=0.62 we observed strong broadening, indicating phase separation.

Empirical Identification of Uranium Oxides and Fluorides Using Electron Energy-loss Spectroscopy in the Transmission Electron Microscope

1999 ◽  
Vol 5 (6) ◽  
pp. 437-444 ◽  
Author(s):  
Stephen B. Rice ◽  
Hazel H. Bales ◽  
John R. Roth ◽  
Allen L. Whiteside
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Contaminated Soils ◽  
Core Loss ◽  
Uranium Oxides ◽  
Low Loss ◽  
Electron Dose ◽  
Core Losses ◽  
Electron Energy Loss

Abstract: A set of uranium compound particles relevant to contaminated soils and other environmental concerns surrounding uranium bioavailability were studied by electron energy-loss spectroscopy (EELS). Core-loss EELS results suggest that uranium 4+ compounds have an energy loss resolvable from 6+ compounds. Shoulders on the uranium O4,5 edge further distinguish UO2 from UF4. Low-loss characteristics distinguish carbon-free uranium oxide specimens on holey substrates. In the presence of carbon, correction techniques must be applied. Uranium oxides, fluorides, and minerals show a tendency toward reduction of uranium toward 4+ under the beam. The electron dose required to achieve the transformation from 6+ to 4+ is more severe than that usually required to obtain satisfactory spectra, but the possibility for reduction should be considered. The conditions for low-loss analysis need not be as vigorous as those for core losses, and can be done without altering the valence of most oxides.

High Throughput Phase Mapping for Metrology Using Low-Loss EELS

2017 ◽  
Author(s):  
Lianfeng Fu ◽  
Lifan Chen ◽  
Haifeng Wang
Keyword(s):  
Data Storage ◽  
High Throughput ◽  
Core Loss ◽  
Mapping Technique ◽  
Chemical Information ◽  
Low Loss ◽  
Finger Printing ◽  
Plasmon Loss ◽  
Phase Mapping ◽  
Electron Energy Loss

Abstract The plasmon-loss region of the low-loss electron energy loss spectroscopy (EELS) contains chemical information similar to core-loss EELS; therefore it can be utilized as finger-printing elements. A high throughput phase mapping technique based on plasmon energy (Ep) is proposed. We have successfully applied this phase mapping technique into two case studies in our magnetic head manufacturer processes. This Ep phase mapping can be applied to not only the data storage but also semiconductor industries.

Characterization of Ga-Mn Decagonal Quasicrystals in GaAs

2000 ◽  
Vol 643 ◽  
Author(s):  
K. Sun ◽  
N. D. Browning
Keyword(s):  
Magnetic Moments ◽  
Core Loss ◽  
Contrast Imaging ◽  
Low Loss ◽  
Plasmon Peak ◽  
Decagonal Quasicrystals ◽  
Icosahedral Quasicrystals ◽  
Z Contrast ◽  
Electron Energy Loss

AbstractGa-Mn decagonal quasicrystals (DQC), as well as a Ga-Mn approximant and a normal crystal in GaAs are investigated by electron energy-loss spectroscopy (EELS) and energy dispersive X- ray spectroscopy (EDS) combined with Z-contrast imaging. Plasmon peak positions (Ep), full- width-half-maxima (FWHM) and Mn L3/L2ratios of these three phases are derived from their low-loss spectra and core-loss spectra respectively. Mn, Ga and As distributions in ion implanted GaAs layers are characterized by EDS at line-scan mode. These results show that the Ga-Mn DQC has higher Ep and FWHMs than those of its normal crystal counterpart, as well as all other reported QCs. The much larger L3/L2 intensity ratio of the Ga-Mn DQC over that of the Al-Mn icosahedral quasicrystals (IQC) may suggest Mn atoms in the Ga-Mn DQC have much larger local magnetic moments.

Quantitative energy-filtered tem imaging of interfaces

1996 ◽  
Vol 54 ◽  
pp. 542-543 ◽  
Author(s):  
J. Bentley ◽  
E. A. Kenik ◽  
K. Siangchaew ◽  
M. Libera
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Unit Volume ◽  
Core Loss ◽  
Mean Free Path ◽  
Slit Width ◽  
Elemental Mapping ◽  
Low Loss ◽  
Transmission Electron ◽  
Inelastic Mean Free Path

Quantitative elemental mapping by inner shell core-loss energy-filtered transmission electron microscopy (TEM) with a Gatan Imaging Filter (GIF) interfaced to a Philips CM30 TEM operated with a LaB6 filament at 300 kV has been applied to interfaces in a range of materials. Typically, 15s exposures, slit width Δ = 30 eV, TEM magnifications ∼2000 to 5000×, and probe currents ≥200 nA, were used. Net core-loss maps were produced by AE−r background extrapolation from two pre-edge windows. Zero-loss I0 (Δ ≈ 5 eV) and “total” intensity IT (unfiltered, no slit) images were used to produce maps of t/λ = ln(IT/I0), where λ is the total inelastic mean free path. Core-loss images were corrected for diffraction contrast by normalization with low-loss images recorded with the same slit width, and for changes in thickness by normalization with t/λ, maps. Such corrected images have intensities proportional to the concentration in atoms per unit volume. Jump-ratio images (post-edge divided by pre-edge) were also produced. Spectrum lines across planar interfaces were recorded with TEM illumination by operating the GIF in the spectroscopy mode with an area-selecting slit oriented normal to the energy-dispersion direction. Planar interfaces were oriented normal to the area-selecting slit with a specimen rotation holder.

scholarly journals Analysis of Modular Stator PMSM Manufactured Using Oriented Steel

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6583
Author(s):  
Anmol Aggarwal ◽  
Matthew Meier ◽  
Elias Strangas ◽  
John Agapiou
Keyword(s):  
Magnetic Properties ◽  
Interpolation Method ◽  
Core Loss ◽  
Rolling Direction ◽  
Element Analysis ◽  
Machine Performance ◽  
Core Losses ◽  
Lower Permeability ◽  
Improved Model ◽  
And Control

Oriented steel has higher permeability and lower losses in the direction of orientation (the rolling direction) than non-oriented steel. However, in the transverse direction, oriented steel typically has lower permeability and higher losses. The strategic use of oriented steel in a modular Permanent Magnet Synchronous Machine (PMSM) stator can improve machine performance, particularly when compared to a machine designed with non-oriented steel, by increasing both torque and efficiency. Typically, steel manufacturers provide magnetic properties only in the rolling and transverse directions. Furthermore, in modern Finite Element Analysis (FEA) software, the magnetic properties between the rolling and transverse directions are interpolated using an intrinsic mathematical model. However, this interpolation method has proven to be inaccurate; to resolve this issue, an improved model was proposed in the literature. This model requires the magnetic properties of the oriented steel in between the rolling and transverse directions. Therefore, a procedure for extracting the magnetic properties of oriented steel is required. The objective of this work is to propose a method of determining the magnetic properties of oriented steel beyond just the oriented and transverse directions. In this method, flux-injecting probes, also known as sensors, are used to inject and control the flux density in an oriented steel segmented stator in order to extract the properties of the oriented steel. These extracted properties are then used to model an oriented steel modular stator PMSM. The machine’s average torque and core losses are compared with conventional, non-modular, non-oriented steel stator PMSM, and modular, non-oriented steel stator PMSM. It is shown that both the average torque and the core loss of the oriented steel modular stator PMSM have better performance at the selected number of segments than either of the two non-oriented steel stators.

Plasmon Line Widths of Single Silver Nanoprisms as a Function of Particle Size and Plasmon Peak Position

2007 ◽  
Vol 111 (51) ◽  
pp. 18906-18911 ◽  
Author(s):  
Keiko Munechika ◽  
Jessica M. Smith ◽  
Yeechi Chen ◽  
David S. Ginger
Keyword(s):  
Particle Size ◽  
Peak Position ◽  
Silver Nanoprisms ◽  
Plasmon Peak ◽  
Line Widths

Image-Spectroscopy: New Developments and Applications

1999 ◽  
Vol 5 (S2) ◽  
pp. 618-619 ◽  
Author(s):  
P.J. Thomas ◽  
P.A. Midgley
Keyword(s):  
Spectroscopic Analysis ◽  
Core Loss ◽  
Compositional Analysis ◽  
Single Scattering ◽  
Electron Spectroscopic Imaging ◽  
Low Loss ◽  
Step Size ◽  
New Developments ◽  
Analysis Techniques ◽  
Image Spectroscopy

The ability of modern TEMs to acquire a series of energy filtered images opens up new possibilities in energy loss compositional analysis. In particular, an electron spectroscopic imaging (ESI) series may be treated as a 2-D array of spectra whose resolution is dictated by the step size of the image series, as illustrated in Fig (a). This allows standard spectroscopic analysis techniques to be used on the extracted ‘image-spectra’, such as the removal of plural scattering by deconvolution. Examples of this are given in Fig (b) and (c), which show how Fourier-log and Fourier-ratio deconvolution can be used to recover the single scattering distribution (SSD) from both the low-loss and core-loss regions from a Cr specimen. A pure elemental sample is ideal for testing the validity of such analysis techniques for quantitative compositional mapping, and more details of this method will be published elsewhere. Further, for many simple metal systems, such as steels and alloys, and for simple semiconductors it is possible to model the plasmon contribution using a simple Drude-Lorentz model.

scholarly journals Modeling of Magnetic Elements Including Losses—Application to Variable Inductor

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1865 ◽  
Author(s):  
Sarah Saeed ◽  
Ramy Georgious ◽  
Jorge Garcia
Keyword(s):  
Core Loss ◽  
Magnetic Element ◽  
Power Electronic Converters ◽  
Empirical Formulas ◽  
Magnetic Elements ◽  
Main Emphasis ◽  
Core Losses ◽  
Variable Inductor ◽  
Variable Power ◽  
Core Variable

This paper proposes and develops a circuit-based model aiming to simulate variable magnetic power elements in power electronic converters. The derived model represents the magnetic element by a reluctance-based equivalent circuit. The model takes into consideration device core losses, with the main emphasis given to hysteresis losses, which are modeled using the Jiles-Atherton model. The core loss model is further validated on different ferromagnetic materials to prove its range of applicability. The winding losses of the magnetic device are also taken into consideration, which are obtained using Dowell empirical formulas. In addition, the frequency dependence of the device losses is also considered. The proposed modeling procedure has been applied to study and characterize a double E-core variable power inductor structure in a 1 kW SiC full bridge DC-DC converter. The procedure has been verified by comparing the simulation results to the experimental measurements, confirming the validity and accuracy of the full circuit-based model.

Review on Applications of Low Loss Amorphous Metals in Motors

2010 ◽  
Vol 129-131 ◽  
pp. 1366-1371 ◽  
Author(s):  
S.R. Ning ◽  
Jun Gao ◽  
Y.G. Wang
Keyword(s):  
Magnetic Materials ◽  
Amorphous Alloys ◽  
Amorphous Metals ◽  
Important Process ◽  
Low Loss ◽  
New Class ◽  
The Core ◽  
The Past ◽  
Magnetic Performance ◽  
Core Losses

During the past decade a new class of magnetic materials-amorphous metals, has been under development. This material offers the potential of reducing the core losses of motors dramatically due to its excellent magnetic performance. Thus, the incentive is tremendous to develop cost-competitive motors utilizing amorphous alloys. However, there were some deficiency of a relatively high brittleness and a low stacking factor, which makes it difficult to stamp or cut the material to the shapes that motors required. This paper will briefly review some of the important process technical of magnetic amorphous alloys cores and will describe the results of applying this material in all kind of test motors.

scholarly journals Comparison and assessment of a different steel materials based on core losses reduction for three-phase induction motor

2021 ◽  
Vol 12 (1) ◽  
pp. 29
Author(s):  
Yaser Atta Yassin ◽  
Ali Nasser Hussain ◽  
Nagham Yassin Ahmed
Keyword(s):  
Induction Motor ◽  
Core Loss ◽  
Low Carbon Steel ◽  
Core Material ◽  
Low Carbon ◽  
The Core ◽  
Steel Material ◽  
Three Phase ◽  
Core Losses ◽  
And Performance

This paper presents a core losses and performance calculation with different type of steel materials in the core design for three-phase induction motor by using "ANSYS Maxwell" program in order to identify the core material that provides the most effective performance by iron losses reduction. The coefficients of core losses are calculated from the magnetization curve and core Loss curve based on the on steel material databases. Although the difficult to obtain because of the little of existing information. Results show the capability of the proposed Cobalt steel (Hiperco 50) to achieve the significant losses reduction in comparison to the Electrical Steel NGO–AK Steel’s M-19 and Low Carbon Steel-SAE1020.

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