Modulated structures of Bi-based high-Tc superconducting oxides studied by High Resolution Electron Microscopy and electron diffraction

1990 ◽  
Vol 48 (4) ◽  
pp. 80-81
Author(s):  
Sigemaro Nagakura ◽  
Yoshihiko Hirotsu ◽  
Naoki Yamamoto ◽  
Katsumi Miyagawa ◽  
Yuji Ikeda ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
High Tc ◽  
Modulated Structures ◽  
Resolution Electron ◽  
Incommensurate Structures ◽  
Superconducting Oxides ◽  
Electron Microscopes

In the superconducting Bi-Sr-Ca-Cu-O system, ideal compositions of the low Tc(Tc∼90 K) and the high Tc(Tc∼110K) phases are Bi2Sr2CaCu2Oy(y∼8:2212 phase) and Bi2Sr2Ca2 Cu3Oy (y∼10:2223 phase), respectively. The fundamental structures of these phases are tetragonal with parameters: at=bt=0.54 and ct=3.08 nm for the 2212 phase, and at=bt=0.54 and ct=3.71 nm for the 2223 phase. These phases have incommensurate structures with modulation along their b-axes. In this study, the modulated structures of Pb-doped 2212 and 2223 phases have been investigated by means of high resolution electron microscopy and electron diffraction. Samples Bi2-xPbxSr2CaCu2Oy(x=0-0.4, melt-quenched and annealed) and Bi2−xPbxSr2Ca2Cu3Oy(x=0-0.6, sintered) were observed in high resolution electron microscopes operating at 200 kV and 1 MV.Analysis of the incommensurate modulated structures of the 2212 and 2223 phases was made by using samples Bi2Sr2CaCu2Oy and Bi1.6Pb0.4Sr2Ca2Cu3Oy. The lattice parameters of the incommensurate superstructures are a=at and c=ct for both of these phases, but b∼5bt and b∼bt for the 2212 and 2223 phases, respectively.

Atomic structure imaging of the Si/SiO2 interface with high-resolution electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 390-391
Author(s):  
J.L. Batstone ◽  
J.M. Gibson ◽  
Alice.E. White ◽  
K.T. Short
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Medium Voltage ◽  
Voltage Electron ◽  
Resolution Electron ◽  
Structural Image ◽  
Electron Microscopes ◽  
Point To Point

High resolution electron microscopy (HREM) is a powerful tool for the determination of interface atomic structure. With the previous generation of HREM's of point-to-point resolution (rpp) >2.5Å, imaging of semiconductors in only <110> directions was possible. Useful imaging of other important zone axes became available with the advent of high voltage, high resolution microscopes with rpp <1.8Å, leading to a study of the NiSi2 interface. More recently, it was shown that images in <100>, <111> and <112> directions are easily obtainable from Si in the new medium voltage electron microscopes. We report here the examination of the important Si/Si02 interface with the use of a JEOL 4000EX HREM with rpp <1.8Å, in a <100> orientation. This represents a true structural image of this interface.

HIGH RESOLUTION ELECTRON MICROSCOPY OF THE HIGH Tc SUPERCONDUCTOR Bi2Sr2CaCu2O8+δ

1988 ◽  
Vol 02 (06) ◽  
pp. 835-839 ◽  
Author(s):  
M. HERVIEU ◽  
B. DOMENGES ◽  
C. MICHEL ◽  
B. RAVEAU
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction Study ◽  
High Resolution Electron Microscopy ◽  
Basic Structure ◽  
Tetragonal Symmetry ◽  
High Tc ◽  
Resolution Electron ◽  
High Resolution Images ◽  
New Superconductor

The new superconductor Bi 2 Sr 2 CaCu 2 O 8+δ with T c ranging from 80 to 105K, was studied by electron microscopy. The electron diffraction study shows a pseudo-tetragonal symmetry with a≈b≈5.4 Å and c≈30.7 Å and satellites along a, which settle in an incommensurate way. The high resolution images agree with the proposed basic structure. The stacking of the ( BiO y)2 and [ Sr 2 CaCu 2 O 6] layers is quite regular, with only some defects corresponding to c≈24 Å. The lamellar character of the oxide results in splitting and bending of the crystals.

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.

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