High resolution STEM imaging study on high Tc superconductor YBa2CuaO7-x

1988 ◽  
Vol 46 ◽  
pp. 882-883
Author(s):  
H.-J. Ou ◽  
J. M. Cowley
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Grain Boundary ◽  
Strong Field ◽  
Imaging Study ◽  
Structure Defects ◽  
High Tc ◽  
High Tc Superconductor ◽  
Diffraction Patterns ◽  
Lattice Planes

Using the dedicate VG-HB5 STEM microscope, the crystal structure of high Tc superconductor of YBa2Cu3O7-x has been studied via high resolution STEM (HRSTEM) imaging and nanobeam (∽3A) diffraction patterns. Figure 1(a) and 2(a) illustrate the HRSTEM image taken at 10' times magnification along [001] direction and [100] direction, respectively. In figure 1(a), a grain boundary with strong field contrast is seen between two crystal regions A and B. The grain boundary appears to be parallel to a (110) plane, although it is not possible to determine [100] and [001] axes as it is in other regions which contain twin planes [3]. Following the horizontal lattice lines, from left to right across the grain boundary, a lattice bending of ∽4° is noticed. Three extra lattice planes, indicated by arrows, were found to terminate at the grain boundary and form dislocations. It is believed that due to different chemical composition, such structure defects occur during crystal growth. No bending is observed along the vertical lattice lines.

Structural and phase equilibria studies in the system Pt-Fe-Cu and the occurrence of tulameenite (Pt2FeCu)

1985 ◽  
Vol 49 (353) ◽  
pp. 547-554 ◽  
Author(s):  
M. Shahmiri ◽  
S. Murphy ◽  
D. J. Vaughan
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Critical Temperature ◽  
Grain Boundary ◽  
Phase Region ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Slow Cooling ◽  
X Ray ◽  
Diffraction Patterns

AbstractThe crystal structure and compositional limits of the ternary compound Pt2FeCu (tulameenite), formed either by quenching from above the critical temperature of 1178°C or by slow cooling, have been investigated using X-ray diffraction, transmission electron microscopy, differential thermal analysis and electron probe microanalysis.The crystal structure of Pt2FeCu, established using electron density maps constructed from the measured and calculated intensities of X-ray diffraction patterns of powdered specimens, has the (000) and (½½0) lattice sites occupied by Pt atoms and the (½0½) and (0½½) sites occupied by either Cu or Fe atoms in a random manner. The resulting face-centred tetragonal structure undergoes a disordering transformation at the critical temperature to a postulated non-quenchable face-centred cubic structure. Stresses on quenching, arising from the ordering reaction, are relieved by twinning along {101} planes or by recrystallization along with deformation twinning; always involving grain boundary fracturing.Phase relations in the system Pt-Fe-Cu have been investigated through the construction of isothermal sections at 1000 and 600°C. At 1000°C there is an extensive single phase region of solid solution around Pt2FeCu and extending to the binary composition PtFe. At 600°C the composition Pt2FeCu lies just outside this now reduced area of solid solution in a two-phase field. Comparison of the experimental results with data for tulameenite suggests that some observed compositions may be metastably preserved. The occurrence of fine veinlets of silicate or other gangue minerals in tulameenite is suggested to result from grain boundary fracturing on cooling below the critical temperature of 1178°C and to be evidence of a magmatic origin.

The influence of Th substitution on the crystal structure and the crystal field spectrum of the high-Tc superconductor HoBa2Cu3O6.95

2004 ◽  
Vol 350 (1-3) ◽  
pp. E335-E337
Author(s):  
N Golosova ◽  
A Mirmelstein ◽  
V Bobrovskii ◽  
E Mitberg ◽  
A Podlesnyak ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Field ◽  
High Tc ◽  
High Tc Superconductor ◽  
Field Spectrum

Crystal structure of the high-Tc superconductor HoSr2Cu2.7Mo0.3O7.54 by joint time-of-flight neutron/X-ray rietveld refinement

1995 ◽  
Vol 119 (1) ◽  
pp. 115-119 ◽  
Author(s):  
William T.A. Harrison ◽  
Stan Roliard ◽  
John T. Vaughey ◽  
Lumei Liu ◽  
Allan J. Jacobson
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Time Of Flight ◽  
High Tc ◽  
X Ray ◽  
High Tc Superconductor

scholarly journals High resolution electron microscopy study of the high Tc superconductor Tl0.5Pb0.5Sr4Cu2CO3O7

1993 ◽  
Vol 4 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Maryvonne Hervieu ◽  
Claude Michel ◽  
Marielle Huve ◽  
Christine Martin ◽  
Antoine Maignan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
High Tc ◽  
High Tc Superconductor ◽  
Resolution Electron

ChemInform Abstract: Crystal Structure of the High-Tc Superconductor Tl2Ba2Ca2Cu3O10.

ChemInform ◽  
1989 ◽  
Vol 20 (1) ◽  
Author(s):  
H. H. OTTO ◽  
T. ZETTERER ◽  
K. F. RENK
Keyword(s):  
Crystal Structure ◽  
High Tc ◽  
High Tc Superconductor

The ICDD/PDF Coverage of the High Tc Superconductor and Related Compounds in the A-R-Cu-O Systems (A = Ba, Sr and Ca, and R = Lanthanides and Y)

1992 ◽  
Vol 7 (3) ◽  
pp. 125-133 ◽  
Author(s):  
Winnie Wong-Ng
Keyword(s):  
Powder Diffraction ◽  
Cross Correlation ◽  
Reaction Products ◽  
Powder Diffraction File ◽  
High Tc ◽  
X Ray ◽  
High Tc Superconductor ◽  
Different Types ◽  
Diffraction Patterns ◽  
Related Compounds

AbstractA compilation has been made of the X-ray powder diffraction patterns of the high Tc superconductor and related phases in the systems of Ba-R-Cu-O, Sr-R-Cu-O and Ca-R-Cu-O, where R = yttrium and lanthanides. In addition to the patterns of compounds found in these systems, other related compounds included are cation substitution products of the high Tc phases of Ba2RCu2O6+x, potential reaction products with different types of sample containers, and selected thin-film substrates. The International Centre for Diffraction Data/Powder Diffraction file (ICDD/PDF) coverage includes Sets 1 to 41. A cross correlation of these phases with those reported in Phase Diagrams For Ceramists (PDFC), has also been completed. Results of these efforts are tabulated.

Refinement of rigid shift component normal to a Σ5 grain boundary in rutile by quantitative HREM

1995 ◽  
Vol 53 ◽  
pp. 570-571
Author(s):  
S. Paciornik ◽  
D. Michel ◽  
U. Dahmen
Keyword(s):  
High Resolution ◽  
Grain Boundary ◽  
Rigid Body ◽  
Boundary Plane ◽  
Sufficient Accuracy ◽  
Atomic Relaxation ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Macroscopic Parameters

In contrast to the macroscopic parameters of a grain boundary, its microscopic parameters are difficult to determine with sufficient accuracy to make critical comparisons between models and experimental observations. Whereas the axis and angle of misorientation and the orientation of the boundary plane are easily measured from diffraction patterns or high resolution images, the rigid body shift and the localized atomic relaxation are far more complicated to determine and are more sensitive to image or sample artifacts. Yet it is only these microscopic parameters that differentiate the behavior of the same crystallographic interface in different materials. While the angle of misorientation and the plane of inclination are fixed macroscopically, the rigid body shift and localized atomic relaxations depend directly on the type of bonding that characterizes a given material.Several methods for the measurement of rigid shifts at interfaces have been given recently. Their accuracy is limited by instrumental parameters such as beam tilt, sample tilt, residual two-and threefold astigmatism, specimen noise or twist components.

Crystal structure and microstructure of high-Tc superconducting Bi2Sr2CanCun+1O6+2n+δ

1989 ◽  
Vol 47 ◽  
pp. 158-159
Author(s):  
O. Eibl
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Crystal Defects ◽  
Group Symmetry ◽  
Bravais Lattice ◽  
High Tc ◽  
Space Groups ◽  
Planar Crystal ◽  
In Series ◽  
Diffraction Patterns

Results of the analyses of the crystal structure and crystal defects of high-Tc Bi2Sr2CanCun+1Oz ceramics are presented. Specimen were prepared in a conventional mixed oxide process. In series of electron diffraction patterns of the (n=1) phase(Tc≈ 80 K) reflections appear which are not consistent with the Bbmb space group symmetry suggested in the litterature. Extinction conditions obtained from electron diffraction patterns are compared to extinction conditions of space groups (e.g. Pbmb and Pbnb) which have a primitive Bravais lattice and are “klassengleiche” subgroups of Bbmb.Planar crystal defects on (001) planes were observed in Bi2Sr2CanCun+1Oz phases. These defects are (i) intrinsic and extrinsic (001) stacking faults forming lamellae of {n=0,1,2,3,4) phases and (ii) (001) twin boundaries. An extrinsic (001) stacking fault in the {n=1) phase is shown in fig.1. The image was obtained with a 400 kV electron beam in a microscope equippped with a pole piece with small spherical aberation (Cs= 1mm).

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