Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

scholarly journals Electron Microscopy for Atomic/Electronic Structure of Quasicrystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C1193-C1193
Author(s):  
Eiji Abe
Keyword(s):  
Electron Microscopy ◽  
Electronic Structure ◽  
Scanning Transmission Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Aperiodic Order ◽  
Scanning Transmission ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Key Questions

As stated with special emphasis in the Noble Lecture by Dr. Shechtman, the quasicrystal discovery is definitely the victory of electron microscopy – the first icosahedral stereogram was constructed by a series of electron diffraction patterns from a tiny quasicrystalline grain, and the following high-resolution electron microscope images indeed confirmed a unique aperiodic order that can never be consistent with twinning of normal crystals. Almost thirty years after these early electron microscopy studies, we are now in the era of aberration-corrected electron microscopy which realizes a remarkable resolution beyond an Ångstrom scale [1, 2]. In the talk, I will describe the local atomic/electronic structure of quasicrystals using state-of-the-art scanning transmission electron microscopy, providing several striking insights that may lead to the answers for the longstanding key questions; "Where are the atoms? And why do quasicrystals form?"

Electron Microscope Study of Cation-Deficient Chalcogenide Spinels

1982 ◽  
Vol 21 ◽  
Author(s):  
Y. Komura ◽  
S. Takeda
Keyword(s):  
Electron Microscope ◽  
X Ray ◽  
Disordered Structures ◽  
Spinel Compounds ◽  
Vacancy Ordering ◽  
Resolution Electron ◽  
The Matrix ◽  
Lattice Images ◽  
Image Characteristic ◽  
High Resolution Electron Microscope

ABSTRACTHigh-resolution electron microscope observations were carried out on the cation-deficient spinel compounds Ga2/3Cr2S4 and InCr5/3S4. X-ray analysis of both compounds indicates that there exist 1/3 vacancy per formula unit in 8a positions. It was also found that the vacancy ordering occurs in Ga2/3Cr2S4 below about 1100°C, as well as in InCr5/3S4. Lattice images of vacancy ordered and disordered structures were obtained. In some electron micrographs of ordered InCr5/3 S4, several domains of disordered region were observed in between the matrix of the ordered structure. In a [110] image, characteristic lattice defects were observed on the (110) plane.

300kv high-performance analytical TEM (H-9000)

1987 ◽  
Vol 45 ◽  
pp. 108-109
Author(s):  
H. Kobayashi ◽  
H. Sato ◽  
K. Miyauchi ◽  
T. Onai ◽  
K. Shii ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
High Performance ◽  
Image Resolution ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Analytical Microscopy ◽  
High Resolution Electron Microscope

Higher voltage operation has many advantages for transmission electron microscopy.These advantages include better TEM image resolution and ease of specimen imaging. For analytical microscopy, the higher voltage operation has advantages such as higher source brightness, and better spatial resolution.We reported development of a 300kV ultra high resolution electron microscope. At this time, we would like to report an analytical type 300kV electron microscope.We have incorporated a side entry specimen stage which permits ±45° specimen tilt and is convenient for characteristic x-ray detection. We have also incorporated an analytical objective polepiece which has Cs of 2. 5mm, Cc of 2. 3mm and theoretical TEM image resolution of 0.23nm.

Structural imaging of polytypoids in high Tc oxide superconductors

1989 ◽  
Vol 47 ◽  
pp. 156-157
Author(s):  
R. Ramesh ◽  
E. Wang ◽  
J.M. Tarascon ◽  
G. Thomas
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Liquid Nitrogen Temperature ◽  
High Resolution Electron Microscopy ◽  
Oxide Superconductors ◽  
Ion Milling ◽  
Resolution Electron ◽  
The Matrix ◽  
Diffraction Patterns ◽  
Processing Techniques

The structure of the superconducting polytypoid in the newly discovered high Tc super conducting system, Pb2Sr2Cu2Oy has been examined by high resolution electron microscopy, electron diffraction and xray microanalysis. High resolution imaging has shown the presence of the Pb2Sr2Cu2Oy at the grain boundaries. In analogy to the Bi-Ca-Sr-Cu-O(BCSCO)system, it is suggested that this polytypoid could have a lower transition temperature compared to the matrix. This may explain the steps in the resistivity plot. It is also shown that complex cationic ordering, such as replacement of Sr by Ca and/or Y, could lead to extra reflections in the diffraction patterns.Pb-Sr-(Ca-RE)-Cu-O sintered samples were prepared by standard solid state processing techniques. Samples were prepared under 1% flowing oxygen. Samples for electron microscopy were prepared by argon ion milling at liquid nitrogen temperature at 6kV. High resolution electron microscopy was carried out in the Berkeley Atomic Resolution Microscope at 800kV.

scholarly journals A Suspended Floor for High-Performance Electron Microscopy and Nanoscience

2004 ◽  
Vol 12 (5) ◽  
pp. 16-23 ◽  
Author(s):  
Charles Eric Brown ◽  
Alan W. Nicholls ◽  
Thomas J. Royston ◽  
Waleed M. D'Keidek
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
High Performance ◽  
Recent Article ◽  
Concrete Slab ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
Analytical Instrumentation

The recent article in this journal by O'Keefe et al provides an excellent introduction to the complexities that must be considered when embarking on the installation of a high-resolution electron microscope. It should not pass one's notice, however, that the advent of nanoscience has placed ever stricter attention on the control of vibration not just for analytical instrumentation but also for fabrication facilities. In addition to the thick isolated concrete slab-ongratie described in the above article, designs are coming into use (Fig. 1) that incorporate rigid “waffle” floor structures on closely spaced building columns and pneumatically isolated inertia slabs as are used, for example, in the subterranean portion of the NIST Advanced Metrology Laboratory. Each of these approaches might with time also find applications in the design of electron microscopy laboratories. However, each has the problem of rather high expense of construction.

Effect of One-Step and Two-Step Aging Treatments on Microstructure and Properties of an Al-9.0Zn-2.0Mg-2.0Cu Alloy

2018 ◽  
Vol 941 ◽  
pp. 949-954 ◽  
Author(s):  
Kai Wen ◽  
Bai Qing Xiong ◽  
Yong An Zhang ◽  
Zhi Hui Li ◽  
Xi Wu Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Aging Treatment ◽  
High Strength ◽  
High Resolution Electron Microscopy ◽  
Slow Increase ◽  
Microstructure Observation ◽  
Resolution Electron ◽  
The Matrix ◽  
One Step ◽  
Diffraction Patterns

Aging treatments of an Al-9.0Zn-2.0Mg-2.0Cu alloy, which belongs to high strength aluminum alloy widely used in aerospace industry, are investigated by various techniques, including hardness, electrical conductivity, mechanical properties, transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM). The result shows that hardness and conductivity for one-step aging treatment increase with aging time prolongs while those for two-step aging treatment exhibit increment and decrement, respectively. Besides, the ultimate tensile strength (UTS) and yield strength (YS) for one-step and two-step aging treatments show slow increase and obvious decrease, respectively. Based on these, typical T6 and T76 aging regimes are extracted for microstructure observation. The matrix precipitates for the T6 alloy have small size and dispersive distribution while that for the T76 alloy has big size and sparse distribution. The grain boundary precipitates for both exhibit discontinuous distribution and the T76 alloy has larger size and broader precipitate free zones. The selected area diffraction patterns and HREM observations reveal that main precipitates for the T6 alloy are GPI zone, GPII zone and η' phase while for the T76 alloy are η' phase and η phase.

Transmission Electron Microscopy of II-VI/III-V Semiconductor Heteroepitaxial Interfaces

1989 ◽  
Vol 161 ◽  
Author(s):  
D. Li ◽  
N. Otsuka ◽  
J. Qiu ◽  
J. Glenn ◽  
M. Kobayashi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Molecular Beam ◽  
Dark Field ◽  
Group Iii ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Microscope Images ◽  
High Resolution Electron Microscope

ABSTRACTInterfaces of pseudomorphic (100)ZnSe/GaAs and (100)CdTe/InSb heterostructures grown by molecular beam epitaxy have been studied by transmission electron microscopy. High resolution electron microscope images show dark bands with thicknesses of one or two monolayers at the interfaces. The interfaces appear as bright lines in dark field images of the 200 type reflections, while they become dark lines in dark field images of the 400 type reflections. These observations are explained by assuming the existence of interfaces layers of III2VI3 compounds which have structural vacancies in the sublattices of the group III atoms.

Crystal Structures Of L-Nb205 AND L-Ta205

1977 ◽  
Vol 35 ◽  
pp. 188-189
Author(s):  
Sumio Iijima
Keyword(s):  
Electron Microscope ◽  
Complex Nature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resolution Electron ◽  
Unit Cells ◽  
System 2 ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Phase Relationships

Although structures of tantalum pentoxides have been extensively studied, they have not been fully understood because of the complex nature of their X-ray diffraction patterns. In this study we made some observations on crystals of L-Ta2O5 and L-Nb2O5 using a high resolution electron microscope. The latter structure has been believed to be isostructural with L-Ta2O5. The samples were prepared by Dr. Roth at NBS and were parts of the products used for determining phase relationships in niobium pentoxides (1) and the Ta2O5-Ta2WO8 system (2).According to the X-ray data both structures have orthorhombic unit cells with a = 6.2, b = 29.3, c = 3.9Å. The structures are based on the U03-type and the b spacings are nearly 8 times those of the subcell. Electron diffraction (E.D.) patterns of L-Nb2O5 and L-Ta3O5 crystals showing a*-b* reciprocal sections confirmed generally the results of X-ray works (Figs, la and lc).

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