Multidimensional space groups: Tables and standards

A new family of high temperature superconductors based on Pb2Sr2YCu3O9−δ has recently been reported. One method of improving Tc has been to replace Y partially with Ca. Although the basic structure of this type of superconductors is known, the detailed structure is still unclear, and various space groups has been proposed. In our work, crystals of Pb2Sr2YCu3O9−δ with dimensions up to 1 × 1 × 0.25.mm and with Tc of 84 K have been grown and their superconducting properties described. The defects and crystal symmetry have been investigated using electron microscopy performed on crushed crystals supported on a holey carbon film.Electron diffraction confirmed x-ray diffraction results which showed that the crystals are primitive orthorhombic with a=0.5383, b=0.5423 and c=1.5765 nm. Convergent Beam Electron Diffraction (CBED) patterns for the and axes are shown in Figs. 1 and 2 respectively.

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Symmetry breaking in convergent-beam diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154378 ◽

1989 ◽

Vol 47 ◽

pp. 480-481

Author(s):

D.J. Eaglesham

Keyword(s):

Symmetry Breaking ◽

Point Group ◽

X Ray Diffraction ◽

Multiple Diffraction ◽

Space Groups ◽

Atomic Displacements ◽

Small Probe ◽

Phase Sensitive ◽

Convergent Beam

Convergent Beam Electron Diffraction is now almost routinely used in the determination of the point- and space-groups of crystalline samples. In addition to its small-probe capability, CBED is also postulated to be more sensitive than X-ray diffraction in determining crystal symmetries. Multiple diffraction is phase-sensitive, so that the distinction between centro- and non-centro-symmetric space groups should be trivial in CBED: in addition, the stronger scattering of electrons may give a general increase in sensitivity to small atomic displacements. However, the sensitivity of CBED symmetry to the crystal point group has rarely been quantified, and CBED is also subject to symmetry-breaking due to local strains and inhomogeneities. The purpose of this paper is to classify the various types of symmetry-breaking, present calculations of the sensitivity, and illustrate symmetry-breaking by surface strains.CBED symmetry determinations usually proceed by determining the diffraction group along various zone axes, and hence finding the point group. The diffraction group can be found using either the intensity distribution in the discs

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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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Russian Citizens' Representations of the Country's Position in the Geopolitical Space of the Commonwealth of Independent States, Europe, and the World

European Psychologist ◽

10.1027//1016-9040.8.4.238 ◽

2003 ◽

Vol 8 (4) ◽

pp. 238-251

Author(s):

Victor F. Petrenko ◽

Olga V. Mitina ◽

Kirill A. Bertnikov

Keyword(s):

Well Being ◽

Multidimensional Space ◽

Commonwealth Of Independent States ◽

Repertory Grids ◽

Implicit Model ◽

The World ◽

Public Consciousness ◽

Independent States ◽

Invariant Factors

The aim of this research was the reconstruction of the system of categories through which Russians perceive the countries of the Commonwealth of Independent States (CIS), Europe, and the world as a whole; to study the implicit model of the geopolitical space; to analyze the stereotypes in the perception of different countries and the superposition of mental geopolitical representations onto the geographic map. The techniques of psychosemantics by Petrenko, originating in the semantic differential of Osgood and Kelly's “repertory grids,” were used as working tools. Multidimensional semantic spaces act as operational models of the structures of consciousness, and the positions of countries in multidimensional space reflect the geopolitical stereotypes of respondents about these countries. Because of the transformation of geopolitical reality representations in mass consciousness, the commonly used classification of countries as socialist, capitalist, and developing is being replaced by other structures. Four invariant factors of the countries' descriptions were identified. They are connected with Economic and Political Well-being, Military Might, Friendliness toward Russia, and Spirituality and the Level of Culture. It seems that the structure has not been explained in adequate detail and is not clearly realized by the individuals. There is an interrelationship between the democratic political structure of a country and its prosperity in the political mentality of Russian respondents. Russian public consciousness painfully strives for a new geopolitical identity and place in the commonwealth of states. It also signifies the country's interest and orientation toward the East in the search for geopolitical partners. The construct system of geopolitical perception also depends on the region of perception.

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Minimal supergroups and magnetic space groups (III)

Annales de Physique ◽

10.1051/anphys/197702020169 ◽

1977 ◽

Vol 2 ◽

pp. 169-177

Author(s):

E. F. Bertaut

Keyword(s):

Space Groups

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Equivalency relations in magnetic space groups (II)

Annales de Physique ◽

10.1051/anphys/197514090109 ◽

1975 ◽

Vol 14 (9) ◽

pp. 109-124 ◽

Cited By ~ 1

Author(s):

E. F. Bertaut

Keyword(s):

Space Groups

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Solid State Analysis and Theoretical Explorations on Polymorphic and Hydrate Forms of p-Hydroxybenzaldehyde Isonicotinichydrazone: Effect of Additives on Polymorphic Crystallization

10.26434/chemrxiv.6489425.v1 ◽

2018 ◽

Author(s):

Lincy Tom ◽

Victoria A. Smolenski ◽

Jerry P. Jasinski ◽

M.R. Prathapachandra Kurup

Keyword(s):

Hirshfeld Surface ◽

Framework Analysis ◽

Reaction Conditions ◽

Space Groups ◽

Effect Of Additives ◽

Ft Ir ◽

Packing Arrangement ◽

The Stability ◽

Ir And Raman ◽

Isonicotinic Hydrazide

The reaction of p-hydroxybenzaldehyde with an equimolar amount of isonicotinic hydrazide afforded two polymorphic and hydrate forms of p-hydroxybenzaldehyde isonicotinichydrazone (HBIH) by varying the experimental reaction conditions. The compounds are fully characterized by means of single crystal and powder diffraction methods, vibrational spectroscopy (FT-IR and Raman), thermal and elemental analysis. The compound crystallizes in three different forms in two different space groups, P21/c (form PA and PB) and Pbca (PC). The Hirshfeld surface analysis shows the differences in the relative contributions of intermolecular interactions to the total Hirshfeld surface area for the HBIH molecules. The calculated pairwise interaction energies (104-116 kJ/mol) can be related to the stability of the crystals. Energy framework analysis identifies the interaction hierarchy and their topology. The geometry and conformation of the three forms are essentially similar which differ only by packing arrangement.

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Solid State Analysis and Theoretical Explorations on Polymorphic and Hydrate Forms of p-Hydroxybenzaldehyde Isonicotinichydrazone: Effect of Additives on Polymorphic Crystallization

10.26434/chemrxiv.6489425 ◽

2018 ◽

Author(s):

Lincy Tom ◽

Victoria A. Smolenski ◽

Jerry P. Jasinski ◽

M.R. Prathapachandra Kurup

Keyword(s):

Hirshfeld Surface ◽

Framework Analysis ◽

Reaction Conditions ◽

Space Groups ◽

Effect Of Additives ◽

Ft Ir ◽

Packing Arrangement ◽

The Stability ◽

Ir And Raman ◽

Isonicotinic Hydrazide

The reaction of p-hydroxybenzaldehyde with an equimolar amount of isonicotinic hydrazide afforded two polymorphic and hydrate forms of p-hydroxybenzaldehyde isonicotinichydrazone (HBIH) by varying the experimental reaction conditions. The compounds are fully characterized by means of single crystal and powder diffraction methods, vibrational spectroscopy (FT-IR and Raman), thermal and elemental analysis. The compound crystallizes in three different forms in two different space groups, P21/c (form PA and PB) and Pbca (PC). The Hirshfeld surface analysis shows the differences in the relative contributions of intermolecular interactions to the total Hirshfeld surface area for the HBIH molecules. The calculated pairwise interaction energies (104-116 kJ/mol) can be related to the stability of the crystals. Energy framework analysis identifies the interaction hierarchy and their topology. The geometry and conformation of the three forms are essentially similar which differ only by packing arrangement.

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