Detecting Compositional Variations in Fine-Grained Sediments by Transmission Electron Microanalysis

1984 ◽  
pp. 87-108
Author(s):  
P. J. Kershaw
Keyword(s):  
Fine Grained ◽  
Transmission Electron ◽  
Compositional Variations ◽  
Electron Microanalysis

Investigation of low- and high-resistance Ni–Ge–Au ohmic contacts to n+ GaAs using electron microbeam and surface analytical techniques

1996 ◽  
Vol 11 (5) ◽  
pp. 1244-1254 ◽  
Author(s):  
Nancy E. Lumpkin ◽  
Gregory R. Lumpkin ◽  
K. S. A. Butcher
Keyword(s):  
Electron Microscopy ◽  
Ohmic Contacts ◽  
Analytical Electron Microscopy ◽  
Depth Profiling ◽  
Analytical Techniques ◽  
Two Phase ◽  
Low Resistance ◽  
Fine Grained ◽  
Multiphase Microstructure ◽  
Transmission Electron

A process for the formation of low-resistance Ni–Ge–Au ohmic contacts to n+ GaAs has been refined using multivariable screening and response surface experiments. Samples from the refined, low-resistance process (which measure 0.05 ± 0.02 Ω · mm) and the unrefined, higher resistance process (0.17 ± 0.02 Ω · mm) were characterized using analytical electron microscopy (AEM), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and x-ray photoemission spectroscopy (XPS) depth profiling methods. This approach was used to identify microstructural differences and compare them with electrical resistance measurements. Analytical results of the unrefined ohmic process sample reveal a heterogeneous, multiphase microstructure with a rough alloy-GaAs interface. The sample from the refined ohmic process exhibits an alloy which is homogeneous, smooth, and has a fine-grained microstructure with two uniformly distributed phases. XPS analysis for the refined ohmic process sample indicates that the Ge content is relatively depleted in the alloy (relative to the deposited Ge amount) and enriched in the GaAs. This is not evidenced in the unrefined ohmic process sample. Our data lead us to conclude that a smooth, uniform, two-phase microstructure, coupled with a shift in Ge content from the post-alloy metal to the GaAs, is important in forming low-resistance ohmic contacts.

Pulsed Laser Melting of Amorphous Silicon: Time-Resolved and Post-Irradiation Studies

1983 ◽  
Vol 23 ◽  
Author(s):  
D. H. Lowndes ◽  
R. F. Wood ◽  
C. W. White ◽  
J. Narayan
Keyword(s):  
Pulsed Laser ◽  
Threshold Value ◽  
Dynamical Response ◽  
Cross Sectional ◽  
Time Resolved ◽  
Model Calculations ◽  
Fine Grained ◽  
Transmission Electron ◽  
Incident Laser Pulse ◽  
Thermal Melting

ABSTRACTMeasurements of the time of the onset of melting of self-implantation amorphized (a) Si, during an incident laser pulse, have been combined with modified melting model calculations and measurements of surface melt duration to demonstrate that the thermal conductivity, Ka, of a-Si is very low (≃0.02 W/cm-K). Ka is also shown to be the dominant parameter determining the dynamical response of ionimplanted Si to pulsed laser radiation; the latent heat and melting temperature of a-Si are relatively unimportant. Cross-sectional transmission electron micrographs on implantation-amorphized Si layers of several different thicknesses show that for energy densities less than the threshold value for complete annealing there are usually two distinct regions in the re-solidified a-Si, consisting of fine-grained and large-grained polycrystalline Si, respectively. The presence of the fine-grained poly-Si suggests that bulk nucleation occurs directly from the highly undercooled liquid phase. Thermal melting model calculations suggest that the nucleation temperature, Tn is ≃1200°C.

Fine-Grained Structures Associated with Deformation Twin and Its Influence on Tensile Behaviours in a Cold-Rolled Fe-Ni Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 895-900 ◽  
Author(s):  
Tatsuya Morikawa ◽  
Taku Moronaga ◽  
Kenji Higashida
Keyword(s):  
Deformation Twin ◽  
Liquid Nitrogen Temperature ◽  
Invar Alloy ◽  
High Yield ◽  
Fine Grained ◽  
Transmission Electron ◽  
Ni Alloy ◽  
Cold Rolled ◽  
Crystallographic Planes

Fine-grained structures in Fe-36mass%Ni Invar alloy have been investigated by using transmission electron microscopy (TEM). Particular attention has been paid on the role of deformation twinning in the formation of fine-grained structures and its influence on tensile stressstrain behaviours of rolled specimens. In Fe-Ni Invar alloy with a moderate stacking fault energy, deformation twin did not appear in usual cold-rolling at room temperature (RT), where a kind of cell walls was formed and the Cu-type texture was observed. On the other hand, twinning was occurred by rolling when specimens were cooled to liquid nitrogen temperature (LNT) immediately before the rolling. In such case, a fine lamellar structure was developed and the brass-type texture appeared. However, the lamella boundaries did not coincide with any crystallographic planes, and they were intersected with the bands of deformation twin. Specimens rolled by 90% in thickness reduction exhibited tensile stressstrain behaviours similar to those observed in specimens with SPD structures. In particular, specimens rolled at LNT showed high yield strengths and non-uniform deformation.

The Characterization Of Chemical Bath Deposited Cds On Single Crystal InP Substrates

1997 ◽  
Vol 485 ◽  
Author(s):  
G. M. Riker ◽  
M. M. Al-Jassim ◽  
F. S. Hasoon
Keyword(s):  
Electron Microscopy ◽  
Single Crystal ◽  
Surface Cleaning ◽  
Film Morphology ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Fine Grained ◽  
Transmission Electron ◽  
Cds Thin Films ◽  
Inp Substrates

AbstractWe have investigated CdS thin films as possible passivating window layers for InP. The films were deposited on single crystal InP by chemical bath deposition (CBD). The film thickness, as optically determined by ellipsometry, was varied from 500 to 840Å. The film morphology was investigated by high resolution scanning electron microscopy (SEM), whereas the film microstructure was studied by X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM). Most of the films were fine-grained polycrystalline CdS, with some deposition conditions resulting in epitaxial growth. Cross-sectional TEM examination revealed the presence of interface contaminants. The effect of such contaminants on the film morphology and microstructure was studied, and various approaches for InP surface cleaning/treatment were investigated. The epitaxial films were determined to be hexagonal on both the (111) and (100) InP substrates; however, they were heavily faulted.

Electron Microscopy Analysis of the Intermediate Phases Formed During the Nucleation of Yba2cu3O7-δ Film

2001 ◽  
Vol 7 (S2) ◽  
pp. 424-425
Author(s):  
Lijun Wu ◽  
Yimei Zhu ◽  
V. F. Solovyov ◽  
H. J. Wiesmann ◽  
M. Suenaga
Keyword(s):  
Electron Microscopy ◽  
Electrical Power ◽  
Stoichiometric Ratio ◽  
Transmission Electron Microscopy Analysis ◽  
Fine Grained ◽  
Intermediate Phases ◽  
Transmission Electron ◽  
Gas Atmosphere ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis

Recently, considerable efforts have been made in growing bi-axially aligned thick Yba2cu3O7 (YBCO) films on a flexible, textured metallic substrate for electrical power applications. The BaF2 post-deposition annealing process is one of the most promising methods. to understand the nucleation and growth mechanism of YBCO in this process, extended transmission electron microscopy analysis has been made. Here, we report on the evolution of Ba-Y oxy-fluoride which is pertinent to the epitaxial YBCO nucleation process on SrTiO3 (STO) substrate.The stoichiometric ratio of Y, Cu and BaF2 was evaporated on (00l)-cut STO substrate Subsequently, these films were annealed at 735°C in an O2-H2O-N2 gas atmosphere and quenched after 10, 20, or 40 minutes. The morphology and phase composition of the precursor changed drastically with the annealing times, e.g. after 10 minutes heat treatment, the precursor consisted of fine grained CU2O and Ba-Y(Cu) oxy-fluoride (cubic, a=0.618nm) as shown in fig.la.

Influence of La, Mn and Zn Substitution on the Structure, Magnetic and Absorption Properties of M-Type Barium Ferrites

2020 ◽  
Vol 855 ◽  
pp. 145-153
Author(s):  
Didin Sahidin Winatapura ◽  
Deswita ◽  
Ari Adi Wisnu ◽  
Setyo Purwanto ◽  
Y.F. Buys
Keyword(s):  
Electron Microscope ◽  
Rietveld Method ◽  
Structural Parameters ◽  
Lattice Parameter ◽  
Absorption Properties ◽  
Fine Grained ◽  
Zn Substitution ◽  
Transmission Electron ◽  
Barium Ferrites ◽  
Scherrer Formula

A series of M-type barium ferrites with chemicals composition BaFe12O19 and Ba0.7La0.3Fe(12-2x)(MnZn)xO19 (with x = 0.0, 0.2, 0.5) were synthesized using a chemical coprecipitation based technique. The sample was then called as BFO and BLF, BLFMZ-02 and BLFMZ-05, respectively. The structural parameters were measured by applying the full pattern fitting of Rietveld method using Fullprof program. The crystallite size was calculated using Scherrer formula and Williamson-Hall analysis method, and also confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM). The morphology of particle is composed of fine-grained aggregates with particle size distributions in the range of 70nm - 160nm. The lattice parameter (a = b and c), cell volume (Vcell) and density (ρ) of the samples were found to be changed with La, Mn and Zn substitution due to the dissimilar cationic radii of Ba2+ (1.49Å), La3+ (1.22Å), Fe3+ (0.64Å), Mn3+ (0.89Å) and Zn2+ (0.76Å) ions. The results of sample measurements with Vibrating Sample Magetometer (VSM) indicate that the magnetic behaviours showed that the saturation magnetization (Ms) increased gradually with the substitution of La3+, Mn3+ and Zn3+ ions, whereas the coercivity (Hc) was increase with addition of La3+ ions and then decrease significantly with the addition of Mn3+ and Zn2+ ions. The vector network analyzer (VNA) revealed that microwave absorption measured within 7 – 15 GHz frequency range indicated optimum reflection loss (RL) of-21.50dB at 10.5GHz for BLMZ-02 sample.

Demountable polished extra-thin sections and their use in transmission electron microscopy

1981 ◽  
Vol 44 (335) ◽  
pp. 357-359 ◽  
Author(s):  
D. J. Barber
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Epoxy Resin ◽  
Essential Feature ◽  
Heterogeneous Materials ◽  
Glass Slide ◽  
Thin Sections ◽  
Fine Grained ◽  
Transmission Electron ◽  
Polished Side

The advantages of polished ultra-thin sections (PUTS) in the study of very fine-grained materials, such as occur in some meteorites, have been illustrated by Fredriksson et al. (1978) whose technique is based on the earlier work of Beauchamp and WiUiford (1974). An essential feature of such methods for friable and heterogeneous materials is the use of a medium, usually an epoxy resin, to consolidate and partially impregnate them. Normally one polished side of the specimen is bonded to a glass slide during preparation, and the finished PUTS are integral with the slide on completion. PUTS are typically 2-5 microns in thickness.

A natural example of the disequilibrium breakdown of biotite at high temperature: TEM observations and comparison with experimental kinetic data

1987 ◽  
Vol 51 (359) ◽  
pp. 93-106 ◽  
Author(s):  
A. J. Brearley
Keyword(s):  
Kinetic Data ◽  
Empirical Method ◽  
Reaction Products ◽  
Product Phase ◽  
Fine Grained ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Image Position ◽  
Electron Microscope Data

AbstractTransmission electron microscopy has been used to investigate the mechanism of natural biotite breakdown under pyrometamorphic disequilibrium conditions. Biotite in a xenolith of pelitic gneiss collected from a Tertiary dolerite sill, Isle of Mull, Scotland, shows evidence of an incipient reaction, characterised by a darkening in colour and the appearance of areas of fine-grained reaction products. TEM and analytical electron microscope data show that the reaction can be described as:The orientations of the product phase are controlled by the crystallography of the reacting biotite, demonstrating that the transformation proceeds by a topotactic mechanism. An empirical method, based on the Mg/(Fe2+ + Fe3+) ratios of coexisting spinel and biotite from experimental data, is used to deduce that the reaction occurred above ∼ 770 °C. A comparison of the natural reaction microstructures with those produced experimentally suggest that the xenolith was probably above 800 °C for less than 48 hours and cooled to temperatures of 770 °C after ∼ 150–200 hours.

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