Study of modulated structures by transmission electron microscopy

1985 ◽  
Vol 18 (1-4) ◽  
pp. 97-110 ◽  
Author(s):  
J.W. Steeds ◽  
D.M. Bird ◽  
D.J. Eaglesham ◽  
S. McKernan ◽  
R. Vincent ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Transmission Electron ◽  
Modulated Structures

Transmission Electron Microscopy study of Bi-based superconducting phases

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.

scholarly journals The origin of striation in the metastable β phase of titanium alloys observed by transmission electron microscopy

2017 ◽  
Vol 50 (3) ◽  
pp. 795-804 ◽  
Author(s):  
Jiangkun Fan ◽  
Jinshan Li ◽  
Yudong Zhang ◽  
Hongchao Kou ◽  
Jaafar Ghanbaja ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dark Field ◽  
Atomic Scale ◽  
Intermediate Structure ◽  
Atomic Displacements ◽  
Β Phase ◽  
Transmission Electron ◽  
Modulated Structures ◽  
High Resolution Tem

For the β phase of Ti-5553-type metastable β-Ti alloys, striations in transmission electron microscopy (TEM) bright- and dark-field images have been frequently observed but their origin has not been sufficiently investigated. In the present work, this phenomenon is studied in depth from the macroscopic scale by neutron diffraction to the atomic scale by high-resolution TEM. The results reveal that the β phase contains homogeneously distributed modulated structures, intermediate between that of the β phase (cubic) and that of the α phase or the ω phase (hexagonal), giving rise to the appearance of additional diffraction spots at 1/2, 1/3 and 2/3 β diffraction positions. The intermediate structure between β and α is formed by the atomic displacements on each second {110}βplane in the \langle 1{\overline 1}0\rangle_{\beta} direction, whereas that between β and ω is formed by atomic displacements on each second and third {112}βplane in the opposite \langle 11{\overline 1}\rangle_{\beta } direction. Because of these atomic displacements, the {110}βand {112}βplanes become faulted, resulting in the streaking of β diffraction spots and the formation of extinction fringes in TEM bright- and dark-field images, the commonly observed striations. The present work reveals the origin of the striations and the intrinsic correlation with the additional electron reflections of the β phase.

Modulated Structures in Ion Implanted Al-Fe System

1983 ◽  
Vol 27 ◽  
Author(s):  
K.V. Jata ◽  
D. Janoff ◽  
E.A. Starke
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Purity ◽  
Annealing Treatment ◽  
Modulated Structure ◽  
Transmission Electron ◽  
Modulated Structures ◽  
Ion Energies ◽  
High Purity Aluminum ◽  
Al Matrix

ABSTRACTThe results of transmission electron microscopy studies of iron implantation into high purity aluminum foils are described. For both 50 and 100 + 50 keV incident ion energies, modulated structure has been detected in the as-implanted foils. Upon annealing at 793 K the modulated structure decomposes into the Al matrix and Al3Fe precipitates for the 50 keV implantation. A similar annealing treatment for the 100 + 50 keV implantation indicates that the modulated structure is more stable, although some Fe3Al precipitation occurs.

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

1992 ◽  
Vol 196 (1-2) ◽  
pp. 34-42 ◽  
Author(s):  
Kasumi Yanagisawa ◽  
Yoshio Matsui ◽  
Kaoru Shoda ◽  
Eiji Takayama-Muromachi ◽  
Shigeo Horiuchi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Transmission Electron ◽  
Modulated Structures

Flexible phases, modulated structures and the transmission electron microscope

2004 ◽  
Vol 219 (11) ◽  
Author(s):  
Ray L. Withers ◽  
Lasse Norén ◽  
Yun Liu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Practical Application ◽  
Transmission Electron ◽  
Modulated Structures ◽  
Structural Modulation

AbstractA review of the application of transmission electron microscopy to the study of interface, composite and displacively modulated structures is given. The distinctly different mechanisms underlying structural modulation in each case are emphasized as is the practical application of transmission electron microscopy to problems such as pseudo-symmetry and twinning, to indexation in (3 +

Evidence for Instability in Pb1-x EuxTe Alloys

1987 ◽  
Vol 103 ◽  
Author(s):  
L. Salamanca-Young ◽  
M. Wuttig ◽  
D. L. Partin ◽  
J. Heremans
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Transmission Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
Spinodal Decomposition ◽  
Solid Solutions ◽  
Lattice Spacing ◽  
Molecular Beam ◽  
Transmission Electron ◽  
Modulated Structures

ABSTRACTWe have used transmission electron microscopy to study the structure of Pb1-xEuxTe alloys grown by molecular beam epitaxy. We have observed ordered solid solutions of the Pb1-x EuxTe alloys as well as spinodal decomposition for 0.35≤x<0.75. The spinodal decomposition corresponds to a modulation of both the composition and the lattice spacing of the Pb1-x EuxTe alloy. These modulated structures have periodicities of ∼18Å along the <111> and <110> directions and indicate that the solid solution of Pb1-x Eux Te is unstable in this range of compositions.

scholarly journals Combining powder diffraction with TEM for solving modulated structures

2014 ◽  
Vol 70 (a1) ◽  
pp. C135-C135
Author(s):  
Artem Abakumov
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Real Space ◽  
Space Structure ◽  
Electron Diffraction Data ◽  
Powder Diffraction Data ◽  
Transmission Electron ◽  
Modulated Structures

In many materials competing interactions of different nature may give rise to incommensurate modulations causing extreme structure complexity. Ab initio solution of the modulated structures even with using high quality synchrotron X-ray and/or neutron powder diffraction data appears to be a very challenging problem due to weakness of the satellite reflections, ambiguity in the determination of the modulation vector(s) and superspace symmetry and difficulties in building the initial model for further Rietveld refinement. These problems can be resolved or, at least, mitigated if the diffraction, imaging and spectroscopic advanced transmission electron microscopy techniques are combined with the analysis of powder diffraction data. Complete reconstruction of the reciprocal space, structure solution using quasi-kinematical electron diffraction data, mapping projected scattering density in the unit cell, visualization of the light atoms, displacive and occupational ordering, mapping chemical composition and coordination number can be utilized to reveal the nature of incommensurate modulations and construct the reliable model for the refinement from powder diffraction data. The benefit of the strategy of combining the powder diffraction data with the reciprocal and real space information obtained using aberration-corrected scanning transmission electron microscopy will be illustrated on the examples of the transition metal oxides: Li3xNd2/3-xTiO3 perovskites with frustrated incommensurately modulated octahedral tilting pattern [1]; perovskites (Bi,Pb)1-xFe1+xO3-y, modulated by crystallographic shear planes [2]; CaGd2(1-x)Eu2x(MoO4)4(1-y)(WO4)4y scheelites with incommensurately modulated ordering of cation vacancies [3].

HRTEM study of modulated structures in superconducting Bi2Sr2NdCu2Oy and non-superconducting Bi2Ca2FeOy

1990 ◽  
Vol 48 (4) ◽  
pp. 34-35
Author(s):  
Yoshio Matsui ◽  
Akira Ono ◽  
Kaoru Shoda ◽  
Uk Lee ◽  
Shigeo Horiuchi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Lattice Parameter ◽  
Transmission Electron ◽  
Modulated Structures ◽  
Compression And Expansion ◽  
Incommensurate Modulation ◽  
Point To Point ◽  
Related Compounds

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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