Modulated structures of (Bi1−xPbx)2Sr2CoOy examined by high-resolution transmission electron microscopy

Phenomena of incommensurate modulation in BSCCO superconductors, Bi2Sr2Can−1CunOy (n=1 to 3), have effectively been investigated by high-resolution transmission electron microscopy and it was revealed that periodic compression and expansion of lateral Bi-Bi distance is induced in (BiO)2 layers with a periodicity b=4. 8bg, where bs is a lattice parameter of tetragonal substructure. Longer modulation periodicity is obtained by replacing part of Bi with Pb, while shorter periodicity by replacing Sr (Ca) with La, Y etc. Commensurate modulation structure with shorter periodicity of b=4bs is also found in Bi2Sr2CoOy. In the present study, we examined the modulation structures of two related compounds, superconducting Bi2Sr2NdCu2Oy and non-superconducting Bi2Sr2NdCu2Oy. Electron diffraction and HRTEM observations are made by JEOL's JEM-4000EX type of machine in NRIM (Tsukuba, Japan) with point-to-point resolution of about 0. 17 nm at 400kV.

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High-Resolution Transmission Electron Microscopy of Modulated Structures and Defects in Bi-Sr-Ca-Cu-O Superconductors Prepared by Various Procedures

Journal of Electron Microscopy ◽

10.1093/oxfordjournals.jmicro.a050808 ◽

1990 ◽

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Resolution ◽

Transmission Electron ◽

Modulated Structures

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A study of one-dimensional incommensurate modulated structure determination in high-resolution transmission electron microscopy

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314012005 ◽

2014 ◽

Vol 70 (6) ◽

pp. 563-571 ◽

Cited By ~ 3

Author(s):

Xueming Li ◽

Binghui Ge ◽

Fanghua Li ◽

Huiqian Luo ◽

Haihu Wen

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Resolution ◽

Electron Diffraction ◽

Dimensional Structure ◽

Electron Diffraction Data ◽

Image Deconvolution ◽

Transmission Electron ◽

Modulated Structures ◽

Phase Extension

The methods for determining incommensurate modulated structures (IMSs) in high-resolution transmission electron microscopy have been studied and improved to a level more perfect than before. This is demonstrated by means of the IMS determination for Bi2.31Sr1.69CuO6+δas an example. First, as previously, the projected potential map (PPM) of the IMS with resolution 0.2 nm was obtained after image deconvolution from a [100] image. Secondly, the resolution of the PPM was enhanced to 0.1 nm through phase extension combined with the electron-diffraction data so that the substitutional and displacive modulation functions could be determined. Thirdly, a (2+1)-dimensional structure model that corresponds to the [100] projected IMS was built for calculating the related partial structure factors that were utilized to correct the experimental electron-diffraction intensities for both main and satellite reflections. After three cycles of diffraction-intensity correction and phase extension, all unoverlapped atoms projected along the [100] direction in Bi2.31Sr1.69CuO6+δwere resolved, and the modulations of substitution and displacement could be observed clearly. The substitution of Bi for Sr atoms at the Sr(O) columns was seen in the final PPM and verified by high-dimensional image simulation.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055904 ◽

1982 ◽

Vol 40 ◽

pp. 722-723 ◽

Cited By ~ 1

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.

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Transmission Electron Microscopy study of Bi-based superconducting phases

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173388 ◽

1990 ◽

Vol 48 (4) ◽

pp. 50-51

Author(s):

J.G. Wen ◽

K.K. Fung

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Single Crystals ◽

Microscopy Study ◽

Electron Microscopy Study ◽

Space Groups ◽

Superconducting Phases ◽

Ceramic Samples ◽

Transmission Electron ◽

Modulated Structures

Bi-based superconducting phases have been found to be members of a structural series represented by Bi2Sr2Can−1Cun−1On+4, n=1,2,3, and are referred to as 2201, 2212, 2223 phases. All these phases are incommensurate modulated structures. The super space groups are P2/b, NBbmb 2201, 2212 phases respectively. Pb-doped ceramic samples and single crystals and Y-doped single crystals have been studied by transmission electron microscopy.Modulated structures of all Bi-based superconducting phases are in b-c plane, therefore, it is the best way to determine modulated structure and c parameter in diffraction pattern. FIG. 1,2,3 show diffraction patterns of three kinds of modulations in Pb-doped ceramic samples. Energy dispersive X-ray analysis (EDAX) confirms the presence of Pb in the three modulated structures. Parameters c are 3 0.06, 38.29, 30.24Å, ie 2212, 2223, 2212 phases for FIG. 1,2,3 respectively. Their average space groups are all Bbmb.

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