Showing papers on "Electron backscatter diffraction published in 1974"
TL;DR: X-ray diffraction, electron diffraction and Raman scattering measurements are presented for dehydrated amorphous ZrO2 in this article, showing that the material lacks sufficient crystallinity to diffract X rays.
Abstract: X-ray diffraction, electron diffraction, and Raman scattering measurements are presented for dehydrated amorphous ZrO2. Although the material lacks sufficient crystallinity to diffract X rays, electron diffraction patterns indicate a microcrystallinity with a grain size of 15 to 30 A. Raman spectra characteristic of the metastable tetragonal polymorph were obtained from these materials. Heating the amorphous materials induces recrystallization into first a metastable tetragonal phase and then the stable monoclinic phase.
334 citations
98 citations
Book•
01 Jan 1974
85 citations
01 Jan 1974
79 citations
TL;DR: In this paper, thin films of cobalt, prepared in ultra high-vacuum at 4 K and examined in situ by scanning electron diffraction, are shown to be amorphous with a radial distribution function similar to that obtained theoretically by serial deposition of atoms in the computer-simulated model developed by Bennett.
Abstract: Thin films of cobalt, prepared in ultra-high-vacuum at 4 K and examined in situ by scanning electron diffraction, are shown to be amorphous with a radial distribution function similar to that obtained theoretically by serial deposition of atoms in the computer-simulated model developed by Bennett. The effects of removal of lossy electrons (by velocity filtering), subtraction of substrate background, and multiple scattering on the diffraction profile are investigated and discussed.
75 citations
TL;DR: Electron diffraction patterns were obtained for the first time from single wet phospholipid bilayers and from wet human erythrocyte membranes by using a temperature-controlled electron microscope hydration stage and selective area diffraction showed the existence of semicrystalline domains.
Abstract: Electron diffraction patterns were obtained for the first time from single wet phospholipid bilayers and from wet human erythrocyte membranes by using a temperature-controlled electron microscope hydration stage. Selective area diffraction showed the existence of semicrystalline domains. A structural transition was observed at the transition temperature of the wet dipalmitoyl lecithin bilayer.
58 citations
44 citations
TL;DR: In this paper, the molecular structures of (C5H5)2Mg and (5H 5)2Cr have been determined by gas phase electron diffraction; the C-H bonds in (C 5H5)-2Cr are bent 2·9(1·1)° out of the plane of the C5 ring towards the metal atom.
Abstract: The molecular structures of (C5H5)2Mg and (C5H5)2Cr have been determined by gas-phase electron diffraction; the C–H bonds in (C5H5)2Cr are bent 2·9(1·1)° out of the plane of the C5 ring towards the metal atom.
43 citations
TL;DR: In this article, it is suggested that the structure is essentially two-dimensional, with lattice points regularly spaced along certain lines, but with adjacent lines randomly either in phase or exactly out of phase with their neighbours.
Abstract: A LEED pattern given by a thin film of gold deposited on the (111) surface of a silicon crystal shows an unusual combination of spots and lines. It is suggested that the structure is essentially two-dimensional, with lattice points regularly spaced along certain lines, but with adjacent lines randomly either in phase or exactly out of phase with their neighbours. The authors have simulated this arrangement by optical diffraction and have managed to produce a diffraction pattern with most of the features shown by the LEED pattern.
39 citations
TL;DR: For the C(9)-C(8) bond, the substituents on both atoms are fully eclipsed as discussed by the authors, while for the c(9-C(17) pair, although there is slight staggering, both atoms were fully substituted by relatively bulky groups.
Abstract: ably more flattened, with C(17) only 0.58 ./t removed from the plane of C(9), C(12), C(16) and C(18). There is considerable evidence of molecular strain in this region of the molecule. In particular, two of the bonds radiating from C(9) [C(9)-C(8) 1.583(6)./~; C(9)-C(17) 1.580(5) ,~] are significantly longer than might otherwise be expected for similar bond types in a less restricted environment. For the C(9)-C(8) bond the substituents on both atoms are fully eclipsed, while for the C(9)-C(17) bond, although there is slight staggering, both atoms are fully substituted by relatively bulky groups. Similar lengthening of C spa-C sp 3 bonds has been noted in similar molecules where comparable constraints exist (Cameron, Hair, Greengrass & Ramage, 1974; Beisler, Silverton, Penttila, Horn & Fales, 1971; Gilardi, 1972). In the same context, the valency angles about C(9) [100.4 >115.5°], C(8) [104.2-+114.6°], C(17) [101.7-->120.0 °] and C(18) [100.2-+117.1 °] show considerable distortions from tetrahedral values, the smaller angles in general being endocyclic with respect to the fused ring system, while the larger angles are exocyclic. The relative values of the angles are also in accord with those which would be expected to arise both from the restrictions of the cyclic system, and also from the interactions of bulky substituents. Other dimensions within the molecule compare well with literature values for similar bonding situations. There are no abnormally short intermolecular distances, and the molecular packing would therefore appear to be dominated largely by van der Waals forces.
TL;DR: In this article, an analysis of the elastic low-energy electron diffraction intensities from the low-index faces of aluminum reveals the relatively modest influence on these intensities of the detailed shape of the one-electron optical potential and of the electronic structure of the ion cores.
Abstract: The reflection of an incident «low-energy» (10 eV≲E≲≲500 eV) electron by a solid is dominated by the consequences of its interactions with the valence electrons in the solid. In particular, the high probability that the incident electron suffers an inelastic electron-electron collision renders the elastic electron-solid scattering cross-sections direct measures of the electronic structure and positions of ion cores within 10 A or less of the solid’s surface. We indicate the major features of the coherent reflection,i.e. diffraction, of such low-energy electrons from planar surfaces of single-crystal solids and of current theoretical models of this phenomenon. Emphasis is placed on those features of the electron-electron and electron-ion-core interactions which permit the extraction of the atomic geometry of surface species from measured low-energy electron diffraction (LEED) intensities. Analysis of the elastic low-energy electron diffraction intensities from the low-index faces of aluminum reveals the relatively modest influence on these intensities of the detailed shape of the one-electron optical potential and of the electronic structure of the ion cores. This result, in turn, is used to analyse the atomic structure of Ni(100)-c(2×2)-S, Ni(100)-c(2×2)-O and Cu(100)-c(2×2)-O adsorbed overlayers. Finally, we indicate the present status of applications of LEED intensity analyses to determine the atomic geometry of periodic surface structures.
TL;DR: In this paper, the presence of the V 9 O phase was confirmed and several electron diffraction patterns of important reciprocal lattice planes of this phase were obtained using a long-period superlattice which is 4 × 4 × 6 vanadium atom cells in dimension.
Abstract: Alloys of vanadium containing up to 10 at.% oxygen were examined by transmission electron microscopy, selected-area electron diffraction and X-ray diffraction. The presence of the V 9 O phase was confirmed and several electron diffraction patterns of important reciprocal lattice planes of this phase were obtained. These patterns are explained using a long-period-superlattice which is 4 × 4 × 6 vanadium atom cells in dimension. It is further shown that the sites of this long-period-superlattice correspond to tetrahedral positions for the interstitial atoms. The possibility of octahedral site occupation is discussed.
TL;DR: In this paper, the strain fields in a hot-pressed germanium crystal 8 1/2mm thick were observed in both stereo-paired and section topographs and they were confirmed by X-ray diffraction topography performed on slices cut from the same crystal.
Abstract: Neutron diffraction topography with thermal neutrons has been used to observe the three-dimensional strain fields in a hot-pressed germanium crystal 8 mm thick. In the stereo-paired and section topographs the strain fields were found to be columnar along the press direction. This result was confirmed by X-ray diffraction topography performed on slices cut from the same crystal.
TL;DR: In this paper, the diffraction properties of curved silicon crystals, with curvature radii between ∞ and 25 m obtained by microscopic techniques, were investigated by means of a neutron diffractometer.
Abstract: The diffraction properties of curved silicon crystals, with curvature radii between ∞ and 25 m obtained by microscopic techniques, were investigated by means of a neutron diffractometer. The ratio of neutron reflectivity between plane and curved silicon crystals was measured as a function of the neutron wavelength using different reflecting planes in both Bragg and Laue cases in symmetrical and asymmetrical conditions. The experimental results were interpreted with the results of theoretical investigations on the dynamical theory of diffraction applied to the curved-crystal case. The implications of this work on neutron monochromator design are briefly discussed.
TL;DR: In this article, the existence of several crystallographic shear phases in the family of chromium oxides CrnO2n−1, where n = 4 and 6, was established by electron microscopy and electron diffraction.
TL;DR: In this article, a very thin layer of liquid water nearly in equilibrium with its vapour was created to scatter the penetrating electron beam and usable diffraction patterns could be obtained, but the diffraction pattern was not usable in the case of higher vapour pressure.
Abstract: X-RAY diffraction has been successfully used in determining radial distribution function in liquid water (see references in ref. 1). The few attempts2–7 to apply diffraction of a high energy electron beam to the same end in liquids in general has not led to usable diffraction patterns, particularly in the case of liquids of higher vapour pressure7. To overcome the difficulties arising from the strong absorption of electrons, we produced in an electron microscope a very thin layer of liquid water nearly in equilibrium with its vapour and prevented the pressure in the vicinity of the electron beam for increasing by evaporation. The liquid layer scattered the penetrating electron beam and usable diffraction patterns could be obtained.
TL;DR: In this article, the authors compared the diffraction patterns from a Si crystal taken with a convergent beam of large angular aperture (Kossel pattern) with those from a hollow cone convergent electron beam.
Abstract: Electron diffraction patterns from a Si crystal taken with a convergent beam of large angular aperture (Kossel pattern) are compared with the diffraction pattern taken with a hollow cone convergent electron beam. For thin crystals the patterns are complementary. This behaviour is discussed.
TL;DR: An investigation by electron diffraction, transmission and scanning electron microscopy, and energy-dispersive X-ray analysis has shown that Ta additions to a 40-30-30 Co-Cr-Ni-base alloy strengthen by ordering and by formation of coherent α-Co3Ta precipitate.
Abstract: An investigation by electron diffraction, transmission and scanning electron microscopy, and energy-dispersive X-ray analysis has shown that Ta additions to a 40-30-30 Co-Cr-Ni-base alloy strengthen by ordering and by formation of coherent α-Co3Ta precipitate. However, increasing Ta content increases the proportion of the hexagonal phase and decreases ductility.
TL;DR: In this article, a method is presented for the indexing of satellite diffraction peaks which arise in neutron powder diffraction patterns of spiral spin antiferromagnets with general propagation vectors.
Abstract: A method is presented for the indexing of satellite diffraction peaks which arise in neutron powder diffraction patterns of spiral spin antiferromagnets with general propagation vectors. It has been successfully used to determine the propagation vector in Cu1/2Ga1/2Cr2S4 and also to confirm the direction of the propagation vectors in other materials with known structures.