Alternative approaches to ultra-high resolution imaging

1991 ◽  
Vol 49 ◽  
pp. 650-651
Author(s):  
J.M. Cowley
Keyword(s):  
High Resolution ◽  
High Voltage ◽  
High Resolution Electron Microscopy ◽  
Crystal Defects ◽  
High Resolution Imaging ◽  
General Applicability ◽  
Resolution Electron ◽  
Radiation Resistant ◽  
Resolution Imaging ◽  
Alternative Approaches

By extrapolation of past experience, it would seem that the future of ultra-high resolution electron microscopy rests with the advances of electron optical engineering that are improving the instrumental stability of high voltage microscopes to achieve the theoretical resolutions of 1Å or better at 1MeV or higher energies. While these high voltage instruments will undoubtedly produce valuable results on chosen specimens, their general applicability has been questioned on the basis of the excessive radiation damage effects which may significantly modify the detailed structures of crystal defects within even the most radiation resistant materials in a period of a few seconds. Other considerations such as those of cost and convenience of use add to the inducement to consider seriously the possibilities for alternative approaches to the achievement of comparable resolutions.

Electron-beam-induced 3-D epitaxy Of TiO on TiO2

1988 ◽  
Vol 46 ◽  
pp. 684-685
Author(s):  
M. R. McCartney
Keyword(s):  
High Resolution ◽  
Transition Metal Oxides ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
High Resolution Imaging ◽  
Metallic Oxide ◽  
Resolution Electron ◽  
Resolution Imaging ◽  
Modified Surface ◽  
Electron Stimulated Desorption

It is well-known that the surfaces of maximally-valent transition-metal oxides should be particularly susceptible to electron-stimulated desorption of oxygen under the conditions prevailing in high-resolution electron microscopy (HREM). Indeed, it has been observed that lattice fringes corresponding to TiO have developed on the surfaces of crystals of rutile, TiO2. Fig. 1a shows the modified surface of a rutile crystal tilted to (001)-projection with extensive regions of disorder and small crystallites of reduced (metallic) oxide at the edge; fig. 1b shows TiO2 in a [010]-projection with crystals of TiO in -projection. By combining the techniques of high-resolution imaging, optical diffractogram (ODM) analysis, and computer modeling of crystal structure, a three-dimensional epitaxy for the growth of TiO on TiO2 can be proposed.

Nano-probe x-ray analysis and high-resolution imaging on planar defects in high-pressure synthesized infinite-layer superconductor

1994 ◽  
Vol 52 ◽  
pp. 728-729
Author(s):  
Y. Y. Wang ◽  
H. Zhang ◽  
V. P. Dravid ◽  
H. Zhang ◽  
L. D. Marks ◽  
...  
Keyword(s):  
High Pressure ◽  
High Resolution ◽  
Atomic Structure ◽  
Emission Spectra ◽  
High Resolution Electron Microscopy ◽  
Planar Defects ◽  
X Ray ◽  
Infinite Layer ◽  
Resolution Electron ◽  
Resolution Imaging

Azuma et al. observed planar defects in a high pressure synthesized infinitelayer compound (i.e. ACuO2 (A=cation)), which exhibits superconductivity at ~110 K. It was proposed that the defects are cation deficient and that the superconductivity in this material is related to the planar defects. In this report, we present quantitative analysis of the planar defects utilizing nanometer probe xray microanalysis, high resolution electron microscopy, and image simulation to determine the chemical composition and atomic structure of the planar defects. We propose an atomic structure model for the planar defects.Infinite-layer samples with the nominal chemical formula, (Sr1-xCax)yCuO2 (x=0.3; y=0.9,1.0,1.1), were prepared using solid state synthesized low pressure forms of (Sr1-xCax)CuO2 with additions of CuO or (Sr1-xCax)2CuO3, followed by a high pressure treatment.Quantitative x-ray microanalysis, with a 1 nm probe, was performed using a cold field emission gun TEM (Hitachi HF-2000) equipped with an Oxford Pentafet thin-window x-ray detector. The probe was positioned on the planar defects, which has a 0.74 nm width, and x-ray emission spectra from the defects were compared with those obtained from vicinity regions.

Characterisation of planar crystal defects in Y2Fe17Cx (0.6 ≤ x ≤ 1.6) magnetic material by High Resolution Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 774-775
Author(s):  
W. Coene ◽  
F. Hakkens ◽  
T.H. Jacobs ◽  
K.H.J. Buschow
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Permanent Magnets ◽  
Annealing Treatment ◽  
High Resolution Electron Microscopy ◽  
Crystal Defects ◽  
Ordered Structure ◽  
X Ray ◽  
Planar Crystal ◽  
Resolution Electron

Intermetallic compounds of the type RE2Fe17Cx (RE= rare earth element) are promising candidates for permanent magnets. In case of Y2Fe17Cx, the Curie temperature increases from 325 K for x =0 to 550 K for x = 1.6 . X ray and electron diffraction reveal a carbon - induced structural transformation in Y2Fe17Cx from the hexagonal Th2Ni17 - type (x < 0.6 ) to the rhombohedral Th2Zn17 - type ( x ≥ 0.6). Planar crystal defects introduce local sheets of different magnetic anisotropy as compared with the ordered structure, and therefore may have an important impact on the coercivivity mechanism .High resolution electron microscopy ( HREM ) on a Philips CM30 / Super Twin has been used to characterize planar crystal defects in rhombohedral Y2Fe17Cx ( x ≥ 0.6 ). The basal plane stacking sequences are imaged in the [100] - orientation, showing an ABC or ACB sequence of Y - atoms and Fe2 - dumbbells, for both coaxial twin variants, respectively . Compounds resulting from a 3 - week annealing treatment at high temperature ( Ta = 1000 - 1100°C ) contain a high density of planar defects.

Direct structure analysis of advanced nanomaterials by high-resolution electron microscopy

2012 ◽  
Vol 1 (5) ◽  
pp. 389-425 ◽  
Author(s):  
Takeo Oku
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Nanostructured Materials ◽  
Structure Analysis ◽  
Incident Beam ◽  
High Resolution Electron Microscopy ◽  
Structure Model ◽  
Resolution Electron ◽  
Correction Technique ◽  
Resolution Imaging

AbstractHigh-resolution electron microscopy (HREM) analysis has contributed to the direct structure analysis of advanced nanostructured materials, of which the properties of these materials are strongly dependent on the atomic arrangements. In the present article, the direct structure analysis of nanostructured materials such as boride and oxide materials was described and the high-resolution imaging methods were applied to boron nitride nanomaterials such as nanotubes and nanoparticles. An aberration correction technique is also expected as an advanced nanostructure analysis with higher resolution. The HREM image of TlBa2Ca3Cu4O11 was taken with the incident beam parallel to the a axis together with a structure model after image processing.

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