Transmission electron microscope studies in special ceramics

1978 ◽  
Vol 36 (1) ◽  
pp. 268-269
Author(s):  
A. Zangvil ◽  
L.J. Gauckler ◽  
G. Schneider ◽  
M. Rühle
Keyword(s):  
Phase Diagrams ◽  
Crystal Structures ◽  
Thin Foil ◽  
Limited Extent ◽  
Complex Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Lattice Resolution

The use of high temperature special ceramics which are usually complex materials based on oxides, nitrides, carbides and borides of silicon and aluminum, is critically dependent on their thermomechanical and other physical properties. The investigations of the phase diagrams, crystal structures and microstructural features are essential for better understanding of the macro-properties. Phase diagrams and crystal structures have been studied mainly by X-ray diffraction (XRD). Transmission electron microscopy (TEM) has contributed to this field to a very limited extent; it has been used more extensively in the study of microstructure, phase transformations and lattice defects. Often only TEM can give solutions to numerous problems in the above fields, since the various phases exist in extremely fine grains and subgrain structures; single crystals of appreciable size are often not available. Examples with some of our experimental results from two multicomponent systems are presented here. The standard ion thinning technique was used for the preparation of thin foil samples, which were then investigated with JEOL 200A and Siemens ELMISKOP 102 (for the lattice resolution work) electron microscopes.

Phase diagrams and thermodynamics of rare-earth-doped zirconia ceramics

2007 ◽  
Vol 79 (10) ◽  
pp. 1731-1753 ◽  
Author(s):  
Chong Wang ◽  
Matvei Zinkevich ◽  
Fritz Aldinger
Keyword(s):  
Electron Microscopy ◽  
Experimental Data ◽  
Phase Diagrams ◽  
Heat Content ◽  
X Ray Diffraction ◽  
Zirconia Ceramics ◽  
X Ray ◽  
Transmission Electron ◽  
Diagram Approach ◽  
Rare Earth Doped

Results of the comprehensive experimental and computational phase studies of the systems ZrO2-REO1.5 (RE = La, Nd, Sm, Gd, Dy, Yb) are summarized. Various experimental techniques, X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), transmission electron microscopy (TEM), differential thermal analysis (DTA), and high-temperature calorimetry are employed to study the phase transformation, phase equilibria between 1400 and 1700 °C, heat content and heat capacity of the materials. A lot of contradictions in the literature are resolved, and the phase diagrams are reconstructed. Based on the experimental data obtained in this work and literature, the systems ZrO2-REO1.5 are thermodynamically optimized using the CALPHAD (CALculation of PHase Diagram) approach. Most of the experimental data are well reproduced. Based on the present experiments and calculations, some clear characteristic evolutions with the change of the ionic radius of doping element RE+3 can be concluded.

scholarly journals Structural and morphological tuning of Cu-based metal oxide nanoparticles by a facile chemical method and highly electrochemical sensing of sulphite

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Velayutham Sudha ◽  
Govindhasamy Murugadoss ◽  
Rangasamy Thangamuthu
Keyword(s):  
Crystal Structures ◽  
Chemical Method ◽  
Metal Oxide Nanoparticles ◽  
Modified Electrodes ◽  
Electrochemical Sensing ◽  
Oxide Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
One Step

AbstractA facile one-step chemical method is introduced for the successful synthesis of Cu2O, CuO and CuNa2(OH)4 crystal structures and their electrochemical properties were also investigated. X-ray diffraction studies revealed that these copper-based oxide nanoparticles display different crystal structures such as cubic (Cu2O), monoclinic (CuO) and orthorhombic [CuNa2(OH)4]. The microstructural information of nanoparticles was investigated by transmission electron microscopy. It shows attractive morphologies of different orientation such as rod like structure, nanobeads and well-aligned uniform nanorod for Cu2O, CuO and CuNa2(OH)4, respectively. Electrochemical sensing of sulphite (SO32−) on these three copper-based oxide modified electrodes was investigated. Among the three different crystal structures, CuO shows promising electrocatalytic activity towards oxidation of sulphite. A linear variation in peak current was obtained for SO32− oxidation from 0.2 to 15 mM under the optimum experimental condition. The sensitivity and detection limit were in the order of 48.5 µA cm−2 mM−1 and 1.8 µM, respectively. Finally, practical utility of CuO modified electrode was demonstrated for the estimation of sulphite in commercial wine samples.

scholarly journals Crystal structures of perovskite halide compounds used for solar cells

2020 ◽  
Vol 59 (1) ◽  
pp. 264-305 ◽  
Author(s):  
Takeo Oku
Keyword(s):  
Crystal Structures ◽  
Double Perovskite ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Structures And Properties ◽  
Low Dimensional ◽  
Atomic Coordinates

AbstractThe crystal structures of various types of perovskite halide compounds were summarized and described. Atomic arrangements of these perovskite compounds can be investigated by X-ray diffraction and transmission electron microscopy. Based on the structural models of basic perovskite halides, X-ray and electron diffractions were calculated and discussed to compare with the experimental data. Other halides such as elemental substituted or cation ordered double perovskite compounds were also described. In addition to the ordinary 3-dimensional perovskites, low dimensional perovskites with 2-, 1-, or 0-dimensionalities were summarized. The structural stabilities of the perovskite halides could be investigated computing the tolerance and octahedral factors, which can be useful for the guideline of elemental substitution to improve the structures and properties, and several low toxic halides were proposed. For the device conformation, highly crystalline-orientated grains and dendritic structures can be formed and affected the photo-voltaic properties. The actual crystal structures of perovskite halides in the thin film configuration were studied by Rietveld analysis optimizing the atomic coordinates and occupancies with low residual factors. These results are useful for structure analysis of perovskite halide crystals, which are expected to be next-generation solar cell materials.

The Electron Microscope in Earth Sciences

1978 ◽  
Vol 36 (3) ◽  
pp. 404-419
Author(s):  
H.R. Wenk
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Atomic Scale ◽  
Rock Deformation ◽  
Environmental Geology ◽  
Chemical Analyses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopes

Over the last ten years the electron microscope has become well-established in mineralogical research and what used to be an exotic instrument has found its way into several geology departments. The rapidly growing literature on electron microscopy in mineralogy has recently been summarized (Wenk et al., 1976) and there is not much point in systematically reviewing progress of the last two years. Philosophy and techniques remained largely the same except that there is more emphasis on high resolution, and energy dispersive X-ray detectors have become standard attachments of electron microscopes. Instead I would like to use some examples studied at the Geology Department at Berkeley during the last few months to illustrate a variety of applications in materials which could not be investigated with conventional techniques such as light microscopy, standard chemical analyses and X-ray diffraction. Geology is a broad science which ranges from the study of crystal structures on the atomic scale to processes taking place during mountain building on the scale of the size of continents. The transmission electron microscope has been used in such diverse fields as crystallography, petrology, rock deformation, stratigraphy and environmental geology.

Formation Mechanism of Alumina Nanostrip

2011 ◽  
Vol 399-401 ◽  
pp. 2099-2102
Author(s):  
Shen Jenn Hwang ◽  
Chi Tsung Tsai ◽  
Wei Long Liu
Keyword(s):  
Chemical Composition ◽  
Oxalic Acid ◽  
Crystal Structures ◽  
Blue Light ◽  
Measurement System ◽  
Phosphonic Acid ◽  
Plate Surface ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopes

Alumina nanostrips were prepared on aluminum plate surface by anodizing in oxalic acid and etching in phosphonic acid sequentially. The alumina nanostrips were characterzed by scanning and transmission electron microscopes for the morphologies structuzes,and crystal structures, by an energy dispersive x-ray spectroscope for the chemical composition, and by a photoluminescence measurement system for the photoluminescence. The results show that the alumina nanostrips are amorphous, have a chemical composition of Al2O3-x , and can emit a blue light about 440nm in photoluminescence.

Crystal Structures of Tetrakis(4,4‘-(2,2-diphenylvinyl)-1,1‘-biphenyl)methane:  Transmission Electron Microscopy and X-ray Diffraction

2001 ◽  
Vol 13 (7) ◽  
pp. 2342-2348 ◽  
Author(s):  
C. Y. Yang ◽  
Shujun Wang ◽  
Mathew R. Robinson ◽  
Guillermo C. Bazan ◽  
Alan J. Heeger
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Identification of calcium oxalate crystals in dried or fixed tobacco leaf

1984 ◽  
Vol 42 ◽  
pp. 288-289
Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Growth And Development ◽  
Polarized Light ◽  
Calcium Oxalate Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.

Sign in / Sign up

Export Citation Format

Share Document