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  • 1
    Electronic Resource
    Electronic Resource
    Highly irregular stacking structure in r-BN pressed up to 7.7 GPa at room temperature (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 4241-4245 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structural evolution in rhombohedral-type boron nitride (r-BN) pressed up to 7.7 GPa at room temperature is examined before and after pressing using high-resolution transmission electron microscopy. In the starting state, r-BN is in a platelike form with some folding. The plates consist of an almost perfect 3R structure. After pressing, a large number of stacking faults is formed and causes mixing of 3R and 2H in a few areas and a highly irregular stacking structure in most areas. This means that the coherent slip due to shearing between sp2 sheets is the dominant deformation mechanism in r-BN under high pressure at room temperature. All of these structures cause a broadening of the x-ray diffraction peaks. In some plates, the 2H structure is found in a relatively large area. It has a hexagonal lattice with the stacking sequence of ...ABAB... and lattice constants of a=0.25 nm and c=0.67 nm. The structural evolution in r-BN revealed after pressing is in contrast to that in hexagonal-type BN, in which twinning is the dominant deformation mechanism that introduces the folding of plates under high pressure at high temperature. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366230
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  • 2
    Electronic Resource
    Electronic Resource
    Modulated-Crystal Model for the Twelvefold Quasicrystal Ta62Te38 (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 31 (1998), S. 634-637 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A transmission electron microscopy study reveals that the so-called twelvefold quasicrystal Ta62Te38 is a crystal subjected to structure modulation. It is composed of two incommensurate layers rotated by 30° to each other about their normal. High-resolution electron microscope images show the formation of commensurate domains and their discommensuration. The observed electron diffraction patterns may be explained by a kinematical calculation for the commensurate cell, designated as a 7 × 7 cell. The modulation is considered to be due to the rearrangement of atomic vacancies in response to the occurrence of charge-density waves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889898003008
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  • 3
    Electronic Resource
    Electronic Resource
    The crystal structure of 4Nb2O5.9WO3 studied by 1 MV high-resolution electron microscopy (1978)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 34 (1978), S. 939-946 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Images of pale yellow crystals of 4Nb2O5. 9WO3, obtained with a 1 MV high-resolution electron microscope revealed twinned domains of a tetragonal tungsten bronze structure with a superlattice of 3 x 1 subcells. Comparison with computer calculations suggests that the cations filling the pentagonal tunnels include both Nb and W. Crystals darkened due to reduction on longer heating included no domains and were sensitive to electron irradiation; cations were knocked on from the filled to the vacant pentagonal tunnels. This suggests that some oxygens are released from the -M-O-M-O-M- strings in the tunnels on reduction to weaken the chemical bonding. The number of deficient oxygens is known from the weight gain on oxidizing the crystal. Some additional experiments reveal that there is no '6Nb2O5. 1 IWO3' phase. The resolving power of the present microscope is discussed on the basis of the analysis of the chromatic aberration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739478001928
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  • 4
    Electronic Resource
    Electronic Resource
    New layered structure of Bi2W2O9 determined by 1 MV high-resolution electron microscopy (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 142-145 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The crystal structure of bismuth tungstate, Bi2W2O9, has been examined by 1 MV high-resolution electron microscopy. The symmetry is orthorhombic with lattice parameters a = 5.43, b = 5.41 and c = 23.7 Å and space group Pna21. The point group is determined directly from the images in which each cation site is resolved. The structure is similar to that of conventional layered Bi compounds with respect to the Bi2O2 sheets normal to the c axis; however, the layer between the sheets is of a deformed ReO3 type. The strong chemical bonds between the Bi ions and the apex O atoms cause the rotation of the WO6 octahedron about the c axis. W ions are displaced antiparallel in the WO3 layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739479000255
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of crystal point group by a high-resolution electron microscope image (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 429-430 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Crystal symmetry is exposed in a high-resolution electron microscope image more clearly at the thick part than at the thin part of the crystal, through the dynamical scattering. The crystal point group can be determined by observing how the symmetry in the image changes with thickness. A proposed method is demonstrated with an example of a bismuth titanate, Bi7Ti4NbO21.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739479001030
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  • 6
    Electronic Resource
    Electronic Resource
    (4H)2–4C Type superstructure of TiS1.46 as determined by high-resolution electron microscopy (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 564-569 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The superstructure of titanium sesquisulfide, TiS1.46, is derived on the basis of 1 MV and 100 kV high-resolution electron microscope images. The crystal has monoclinic symmetry (pseudo-hexagonal) with lattice parameters a = 5-92, b = 10.3, c = 22.8 Å and β = 90°. The space group is Cc. The metal vacancies are confined to every second metal layer and ordered within the layer. They are arranged in a stacking sequence of the 4C-type along the c axis. The sulfur atoms are in the 4H-type stacking sequence along the c axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739479001339
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  • 7
    Electronic Resource
    Electronic Resource
    Transition of V6O13 to VO2 observed with a high-resolution electron microscope (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 660-664 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Under irradiation by an intense electron beam a V6O13 crystal reacts with the carbon deposited on the surface during microscopic observation. The structural changes during the reaction were directly observed by means of lattice images, in which the array of VO6 octahedra was resolved. At the initial stage cavities smaller than 20 Å in diameter appear preferentially in the thin part of the crystal and some crystallographic shear planes are formed in their wall. The cavities with the heavily distorted surroundings are seen as white regions. Kinks in lattice fringes, indicating the occurrence of stacking faults, are simultaneously found in the matrix. At the advanced stage the VO2 phase and its twin component are produced. The mechanism of the transition of V6O13 to VO2 can be interpreted in terms of the cooperative movement of octahedra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739475001398
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  • 8
    Electronic Resource
    Electronic Resource
    Absorption of hydrogen in ‘ReO 3 ’ (1979)
    [s.l.] : Nature Publishing Group
    Nature 279 (1979), S. 226-227 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] ReO3 crystals, of a dark purplish-red colour and having a cubic shape with edge of about 0.5 mm, were prepared by a chemical transport method2, and some cubes were crushed in CC14. The conventional powder X-ray diffractometer peaks were identified as ReO3 (a = 3.75 A). On the electron diffraction ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/279226a0
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  • 9
    Electronic Resource
    Electronic Resource
    Structure image of Yb3Fe4O10 by a 1 MV high-resolution electron microscope (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 561-564 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567740879004155
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  • 10
    Electronic Resource
    Electronic Resource
    Structure determination of a mixed-layer bismuth titanate, Bi7Ti4NbO21, by super-high-resolution electron microscopy (1977)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 33 (1977), S. 701-703 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The crystal structure of a bismuth titanate, Bi7Ti4NbO21, was determined on the basis of super-high- resolution images, taken by a recently constructed 1000 kV electron microscope, in which each cation site was approximately defined. It was found that the crystal has a mixed-layer structure, i.e. Bi4Ti3O12 and Bi3TiNbO9-like layers are alternately intergrown. The symmetry is orthorhombic with space group I2cm. The lattice parameters are a = 5.45, b = 5.42 and c = 58.1 Å. That the periodicity along c is twice that expected from a simple intergrowth can be accounted for by the rotation of octahedra. The lattice defects found are discussed in terms of twinning of the crystal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739477001806
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