Ordered structure formation in the flux-grown Ba(Mg1/3Ta2/3)O3 single crystals

2001 ◽  
Vol 16 (6) ◽  
pp. 1593-1599 ◽  
Author(s):  
Yu-Chang Lee ◽  
Chen-Chia Chou ◽  
Dah-Shyang Tsai
Keyword(s):  
Electron Diffraction ◽  
Single Crystals ◽  
Annealing Time ◽  
High Resolution Electron Microscopy ◽  
Maximum Intensity ◽  
Ordered Structure ◽  
X Ray Diffraction ◽  
Resolution Electron ◽  
Higher Temperature ◽  
Diffraction Patterns

Formation of ordered structure in flux-grown Ba(Mg1/3Ta2/3)O3(BMT) single crystals was studied using x-ray diffraction, electron diffraction, and high-resolution electron microscopy. The low-temperature-grown crystals exhibited no sign of B-site ordering. Annealing at 1500 °C induced the 1:2 ordered phase, and its content increased with the annealing time. The superlattice diffraction peaks were broad initially; they sharpened rapidly with the annealing time. Diffuse superlattice reflections were found in electron diffraction patterns of 1500 °C annealed BMT; they turned into sharp reflections under long annealing time or higher temperature, 1600 °C. The intensity of diffuse reflections was sparsely distributed, but the maximum intensity location was determined in the digitized recording of image plate. The maximum intensity sites of two diffuse reflections in the 〈111〉 direction deviated from the presumed 1/3 and 2/3 positions and shifted towards the center. The diffuse reflection and the deviation from regular positions were interpreted as the composition modulation during B-site cation diffusion.

Structure determination of inorganic structures by HREM, Cip, and electron diffraction

1993 ◽  
Vol 51 ◽  
pp. 1204-1205
Author(s):  
Xiaodong Zou ◽  
V.G. Zubkov ◽  
Gunnar Svensson ◽  
Sven Hovmöller
Keyword(s):  
Image Processing ◽  
Electron Diffraction ◽  
Ccd Camera ◽  
High Resolution Electron Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resolution Electron ◽  
Diffraction Patterns ◽  
The Fourier Transform

High resolution electron microscopy (HREM) combined with crystallographic image processing (CIP) is becoming a powerful technique for solving inorganic structures. With the image processing systems CRISP and ELD, running on a personal computer, this technique can be easily established in other laboratories. HREM images and electron diffraction patterns are digitized by a CCD camera and transferred into a PC. Phases and amplitudes are extracted from the Fourier transform of the HREM images. For thin crystals of metal oxides, the phases obtained by HREM and CIP inside the Scherzer resolution of the microscope are identical to the x-ray structure factor phases.Electron diffraction extends to much higher resolution than EM images (beyond 1 Å). The quality of the amplitudes is also higher than that from images, since ED data is not affected by the contract transfer function (CTF). Amplitudes extracted by ELD are close to x-ray diffraction amplitudes (within 30%).

Identification of a new trace 114R SiC by HREM

1999 ◽  
Vol 55 (2) ◽  
pp. 255-257 ◽  
Author(s):  
X. Y. Yang ◽  
G. Y. Shi ◽  
X. M. Meng ◽  
H. L. Huang ◽  
Y. K. Wu
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
Matrix Model ◽  
High Resolution Electron Microscopy ◽  
Stacking Sequence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resolution Electron ◽  
Diffraction Patterns

Using electron diffraction patterns and high-resolution electron microscopy (HREM), a trace 114R SiC in commercial α-SiC powder (mainly 6H SiC according to X-ray diffraction) has been discovered. In a hexagonal unit cell its stacking sequence is [(33)4(34)2]3, the periodicity along the c axis is 286.14 Å and a = b = 3.073 Å. 114R belongs to the structure series of (33) n34(33) m34 predicted theoretically by Pandey & Krishna [Mater. Sci. Eng. (1975), 20, 243–249] on the basis of the faulted matrix model.

Anisotropic radiation damage of potassium tetracyano platinate (KCP)

1978 ◽  
Vol 36 (1) ◽  
pp. 392-393
Author(s):  
N. Uyeda ◽  
E. J. Kirkland ◽  
B. M. Siegel
Keyword(s):  
Electron Diffraction ◽  
Radiation Damage ◽  
Structural Changes ◽  
High Resolution Electron Microscopy ◽  
Radiation Sensitivity ◽  
Resolution Electron ◽  
Damage Process ◽  
Diffraction Patterns ◽  
Fading Rate

The direct observation of structural change by high resolution electron microscopy will be essential for the better understanding of the damage process and its mechanism. However, this approach still involves some difficulty in quantitative interpretation mostly being due to the quality of obtained images. Electron diffraction, using crystalline specimens, has been the method most frequently applied to obtain a comparison of radiation sensitivity of various materials on the quantitative base. If a series of single crystal patterns are obtained the fading rate of reflections during the damage process give good comparative measures. The electron diffraction patterns also render useful information concerning the structural changes in the crystal. In the present work, the radiation damage of potassium tetracyano-platinate was dealt with on the basis two dimensional observation of fading rates of diffraction spots. KCP is known as an ionic crystal which possesses “one dimensional” electronic properties and it would be of great interest to know if radiation damage proceeds in a strongly asymmetric manner.

Atomic structure of YB56 studied by digital high-resolution electron microscopy and electron diffraction

2001 ◽  
Vol 16 (1) ◽  
pp. 101-107 ◽  
Author(s):  
Takeo Oku ◽  
Jan-Olov Bovin ◽  
Iwami Higashi ◽  
Takaho Tanaka ◽  
Yoshio Ishizawa
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Charge Coupled Device ◽  
X Ray ◽  
Resolution Electron ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Simulated Images

Atomic positions for Y atoms were determined by using high-resolution electron microscopy and electron diffraction. A slow-scan charge-coupled device camera which had high linearity and electron sensitivity was used to record high-resolution images and electron diffraction patterns digitally. Crystallographic image processing was applied for image analysis, which provided more accurate, averaged Y atom positions. In addition, atomic disordering positions in YB56 were detected from the differential images between observed and simulated images based on x-ray data, which were B24 clusters around the Y-holes. The present work indicates that the structure analysis combined with digital high-resolution electron microscopy, electron diffraction, and differential images is useful for the evaluation of atomic positions and disordering in the boron-based crystals.

Small-Spot Illumination For High-Resolution Electron Microscopy of Beam-Sensitive Specimens

1985 ◽  
Vol 43 ◽  
pp. 320-321
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Photographic Emulsion ◽  
Lateral Motion ◽  
Small Spot ◽  
Resolution Electron ◽  
Diffraction Patterns

The contrast observed in images of beam-sensitive, crystalline specimens is found to be significantly less than one would predict based on observations of electron diffraction patterns of the specimens. Factors such as finite coherence, inelastic scattering, and the limited MTF of the photographic emulsion account for some decrease in contrast. It appears, however, that most of the loss in signal is caused by motion of the specimen during exposure to the electron beam. The introduction of point and other defects in the crystal, resulting from radiation damage, causes bending and lateral motion, which degrade the contrast in the image. We have therefore sought to determine whether the beam-induced specimen motion can be reduced by reducing the area of the specimen which is illuminated at any one time.

Alternative interpretation of electron diffraction patterns from chrysotile asbestos fibers

1995 ◽  
Vol 53 ◽  
pp. 164-165
Author(s):  
P. Ling ◽  
H. Ling ◽  
H. Kawayoshi ◽  
F. Tsai ◽  
R. Gronsky ◽  
...  
Keyword(s):  
Diffuse Scattering ◽  
High Resolution Electron Microscopy ◽  
Alternative Interpretation ◽  
Circular Cylinders ◽  
Chrysotile Asbestos ◽  
X Ray Diffraction ◽  
Asbestos Fibers ◽  
Single Side ◽  
Resolution Electron ◽  
Diffraction Patterns

Chrysotile asbestos fibers have been the object of intensive study for many years, and their structure and growth mechanisms have perplexed investigators ever since the original 1930 X-ray diffraction work of Warren and Bragg confused superlattice for fundamental reflections along two of the three unit cell directions. Even after the lattice parameters were accurately found, the origins of the characteristic and plentiful diffuse scattering seen in diffraction patterns challenged the most careful analyses. In 1956, Whittaker performed very detailed calculations of the scattering from fibers that were assumed to adopt the structure of concentric circular cylinders, yet could not obtain agreement with experimental results, especially the intensity distribution of subsidiary maxima(diffuse scattering) bordering Bragg reflections on a single side. It took the beautiful high-resolution electron microscopy of Yada to show that the fibers were actually spiral cylinders rather than circular cylinders, an observation that removed some of the minor discrepancies in Whittaker's model.

On the interpretation of electron diffraction patterns from materials containing planar boundaries: the intergrowth tungsten bronzes

1990 ◽  
Vol 429 (1876) ◽  
pp. 91-117 ◽  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
General Interest ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Resolution Imaging ◽  
Diffraction Patterns

Materials containing planar boundaries are of general interest and complete understanding of their structures is important. When direct imaging of the boundaries by, for instance, high-resolution electron microscopy, is impracticable, details of their structure and arrangement may be obtained from electron diffraction patterns. Such patterns are discussed in terms of those from intergrowth tungsten bronzes as specific examples. Fourier-transform calculations for proposed structures have been made to establish, in conjunction with optical-diffraction analogues, the features of the far-field diffraction patterns. These results have been compared with diffraction patterns obtained experimentally by transmission electron microscopy. The aim of the study, to show that the arrangement of the boundaries in these complicated phases can be deduced from their diffraction patterns without the need for high-resolution imaging, has been achieved. The steps to be taken to make these deductions are set out.

scholarly journals Defect-assisted synthesis of magneto-plasmonic silver-spinel ferrite heterostructures in a flower-like architecture

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Marco Sanna Angotzi ◽  
Valentina Mameli ◽  
Claudio Cara ◽  
Vincenzo Grillo ◽  
Stefano Enzo ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Spinel Ferrite ◽  
High Resolution Electron Microscopy ◽  
Careful Study ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Resolution Electron ◽  
Wide Range ◽  
Controlled Morphology ◽  
Diffraction Patterns

Abstract Artificial nano-heterostructures (NHs) with controlled morphology, obtained by combining two or more components in several possible architectures, make them suitable for a wide range of applications. Here, we propose an oleate-based solvothermal approach to design silver-spinel ferrite flower-like NHs. Small oleate-coated silver nanoparticles were used as seeds for the growth of magnetic spinel ferrite (cobalt ferrite and spinel iron oxide) nanodomains on their surface. With the aim of producing homogeneous flower-like heterostructures, a careful study of the effect of the concentration of precursors, the reaction temperature, the presence of water, and the chemical nature of the spinel ferrite was carried out. The magnetic and optical properties of the NHs were also investigated. A heterogeneous growth of the spinel ferrite phase on the silver nanoparticles, through a possible defect-assisted mechanism, was suggested in the light of the high concentration of stacking faults (intrinsic and twins) in the silver seeds, revealed by Rietveld refinement of powder X-ray diffraction patterns and High-Resolution electron microscopy.

Structure and composition in the superconductive Bi–Sr–Ca–Cu–O system

1988 ◽  
Vol 3 (6) ◽  
pp. 1317-1326 ◽  
Author(s):  
A. H. Carim ◽  
A. P. M. Kentgens ◽  
J. H. T. Hengst ◽  
D. M. de Leeuw ◽  
C. A. H. A. Mutsaers
Keyword(s):  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
Modulated Structure ◽  
Multiphase Materials ◽  
Resolution Electron ◽  
Diffraction Patterns

Characterization of superconducting Bi–Sr–Ca–Cu oxides has been carried out by electrical measurements, x-ray diffraction, conventional and high-resolution electron microscopy, and electron microprobe analysis. Nominal starting compositions with cation ratios of 1:1:1:2 and 2:2:1:2 show considerably different superconducting behavior. In both cases multiphase materials are formed. The predominant superconducting phase occurs as thin platelets with an orthorhombic, modulated structure. These particles often have edges aligned along [110], [100], and [010] directions and contain subgrain boundaries. Electron diffraction patterns and high-resolution micrographs taken along several zone axes are consistent with an incommensurate centered modulation along the b axis with a magnitude of 4.7 ± 0.1 times b. Unexpectedly, two distinct chemical compositions were found in platelets with the same apparent structure: Bi4Sr3Ca3Cu4O16±δ for the lower Tc phase in the 1:1:1:2 material, and Bi2Sr2CaCu2O8±δ for the isomorphic higher Tc phase present in the 2:2:1:2 samples.

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