Ordering of Mg and Nb in the octahedral positions of the “cubic” perovskite structure of Pb3MgNb2O9

Author(s):  
H. Brigitte Krause ◽  
Donald L. Gibbon

AbstractSelected-area electron-diffraction patterns and x-ray diffraction powder patterns were taken of crushed single crystals of Pb

1992 ◽  
Vol 7 (3) ◽  
pp. 542-545 ◽  
Author(s):  
Peter C. Van Buskirk ◽  
Robin Gardiner ◽  
Peter S. Kirlin ◽  
Steven Nutt

Epitaxial BaTi3 films have been grown on NdGaO3 [100] substrates by reduced pressure MOCVD for the first time. The substrate temperature was 1000 °C and the total pressure was 4 Torr. Electron and x-ray diffraction measurements indicate highly textured, single phase films on the NdGaO3 substrate which are predominantly [100], with [110] also present. TEM and selected area electron diffraction (SAED) indicate two specific orientational relationships between the [110] and the [001] diffraction patterns.


2014 ◽  
Vol 47 (3) ◽  
pp. 879-886 ◽  
Author(s):  
He Zheng ◽  
Jianbo Wang ◽  
Zhongling Xu ◽  
Jianian Gui

A previous transmission electron microscopy (TEM) analysis revealed the existence of monoclinic Li2MnO3in the lithium-rich and oxygen-deficient Li1.07Mn1.93O4−δpowder. Interestingly, the monoclinic phase exhibits different nanoscale lamellar variants involving a rotation of the stacking direction by 120 or 240° along the pseudo-threefold axis,i.e.the [103]M//[111]C(M and C denote the monoclinic and cubic phases, respectively) zone axis. Here, a theoretical X-ray diffraction (XRD) study of Li2MnO3employing theDIFFaXprogram is presented. It is found that, with the occurrence of different stacking configurations, the characteristic superstructure reflections with 2θ between 20 and 35° (Cu Kα) in the XRD pattern become more and more broadened with the increasing degree of stacking disorder, indicating that XRD may fall short in detecting the presence of the monoclinic Li2MnO3phase. Moreover, selective peak asymmetry appears when the stacking sequence becomes extremely disordered. Further selected-area electron diffraction and theoretical neutron diffraction investigation may clarify the similar ambiguity concerning the crystal phases of other structurally related compound cathode materials for lithium-ion batteries (e.g.LiNi1/2Mn1/2O2, LiNi1/3Co1/3Mn1/3O2).


2013 ◽  
Vol 23 ◽  
pp. 57-65
Author(s):  
San Ju Francis ◽  
J. Nuwad ◽  
Alka Gupta ◽  
J.K. Sainis ◽  
R. Tewari ◽  
...  

A simple gamma irradiation strategy was developed for the synthesis of gold nanoplates by employing polydiallyldimethylammonium chloride (PDDA) as the capping agent. The nanoplates produced had hexagonal, triangular and truncated triangular shapes and the size of the nanoplates could be varied from 500 nm to 5 μm by adjusting the concentration of Au3+ and PDDA in the solution. X-ray diffraction and selected area electron diffraction investigations proved that the nanoplates are single crystals bound by the {111} planes on the top and bottom surfaces. The nanoplates were also characterized by energy dispersive X-ray analysis and X-ray photoelectron spectroscopy.


Author(s):  
Robert M. Glaeser ◽  
David W. Deamer

In the investigation of the molecular organization of cell membranes it is often supposed that lipid molecules are arranged in a bimolecular film. X-ray diffraction data obtained in a direction perpendicular to the plane of suitably layered membrane systems have generally been interpreted in accord with such a model of the membrane structure. The present studies were begun in order to determine whether selected area electron diffraction would provide a tool of sufficient sensitivity to permit investigation of the degree of intermolecular order within lipid films. The ultimate objective would then be to apply the method to single fragments of cell membrane material in order to obtain data complementary to the transverse data obtainable by x-ray diffraction.


2007 ◽  
Vol 7 (2) ◽  
pp. 525-529 ◽  
Author(s):  
Bo Zhou ◽  
Jun-Jie Zhu

A chemical co-reduction route in aqueous solution was developed to synthesize Bi100−xSbx alloys at room temperature. The hydrolyses of Bi(III) and Sb(III) were effectively avoided by selecting proper raw materials and coordinator. X-ray diffraction analysis indicated that the as-prepared Bi100−xSbx alloys were homogeneous and phase-pure, and the Bi/Sb ratios in the alloys were very close to those in the aqueous solutions. The transmission electron microscope observation showed that the as-prepared Bi100−xSbx (x = 0∼100) alloys were particles with a size of tens of nanometers. The selected area electron diffraction patterns confirmed the high crystallinity, the homogeneousness, and the composition controllability of as-prepared alloys. All these characters and the nanometer-scaled size of the alloys are believed to be beneficial to the thermoelectric property of the Bi100−xSbx alloys.


1978 ◽  
Vol 33 (8) ◽  
pp. 918-923 ◽  
Author(s):  
F. Müller ◽  
E. Schulte

Flash-x-ray-diffraction patterns (FXD) with an exposure time of 4 ns of NaCl single crystals compressed by plane shock waves are obtained at pressures of about 30 kbar. From the diffraction patterns the compression is determined and compared with Hugoniot data. During shock load the lattice shows an uniaxial compression. While in case of measurements at the free surface an observation time of only a few nanoseconds is available, this experimental set-up allows an observation time of two microseconds.


Clay Minerals ◽  
1977 ◽  
Vol 12 (1) ◽  
pp. 59-66 ◽  
Author(s):  
M. J. Wilson ◽  
J. M. Tait

AbstractX-ray diffraction and electron microscopy show that halloysite occurs widely in soils derived from a variety of parent rocks (granite, gabbro, schist and slate) in north-east Scotland. Both tubular and non-tubular forms are observed, the latter being characterized by electron diffraction patterns with 001 reflection either absent or very weak and diffuse. Clay fractions from a poorly drained profile separated without prior drying of the soil samples contain essentially dehydrated halloysite at the surface, this becoming progressively more hydrated with depth. Since halloysite occurs extensively in soils of widely varying drainage class the mineral is probably not the result of recent soilforming processes but may have originated during Tertiary or interglacial weathering.


2011 ◽  
Vol 17 (3) ◽  
pp. 403-409 ◽  
Author(s):  
Karen L. Torres ◽  
Richard R. Vanfleet ◽  
Gregory B. Thompson

AbstractEight FePt thin film specimens of various thicknesses, compositions, and order parameters have been analyzed to determine the robustness and fidelity of multislice simulations in determining the chemical order parameter via electron diffraction (ED). The shape of the simulated curves depends significantly on the orientation and thickness of the specimen. The ED results are compared to kinematical scattering order parameters, from the same films, acquired from synchrotron X-ray diffraction (XRD). For the specimens analyzed with convergent beam electron diffraction conditions, the order parameter closely matched the order parameter as determined by the XRD methodology. However, the specimens analyzed by selected area electron diffraction conditions did not show good agreement. This has been attributed to substrate effects that hindered the ability to accurately quantify the intensity values of the superlattice and fundamental reflections.


2008 ◽  
Vol 8 (3) ◽  
pp. 1481-1488 ◽  
Author(s):  
Marguerite Germain ◽  
Philip Fraundorf ◽  
Sam Lin ◽  
Elena A. Guliants ◽  
Christopher E. Bunker ◽  
...  

We describe the synthesis and characterization of srilankite (Ti2ZrO6) nanowires. The nanowires are produced via hydrothermal synthesis with a TiO2/ZrO2 mixture under alkaline conditions. The zirconium titanate nanowires have median diameters of 60 nm and median lengths of 800 nm with the 〈022〉 axis along the length of the nanowire. Electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction, and electron diffraction are used to characterize the phases and compare nanowires produced with varying molar ratios of Ti and Zr. Electron diffraction patterns produced from single nanowires show highly crystalline nanowires displaying a compositional-ordering superlattice structure with Zr concentrated in bands within the crystal structure. This is in contrast to naturally occurring bulk srilankite where Zr and Ti are randomly substituted within the crystal lattice. Streaking is observed in the electron diffraction patterns suggesting short-range ordering within the superlattice structure.


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