Structure of UMoO5 studied by single-crystal X-ray diffraction and high-resolution transmission electron microscopy

1996 ◽  
Vol 52 (6) ◽  
pp. 961-965 ◽  
Author(s):  
O. G. D'yachenko ◽  
V. V. Tabachenko ◽  
R. Tali ◽  
L. M. Kovba ◽  
B.-O. Marinder ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Slight Excess ◽  
Transmission Electron ◽  
Different Types

A combination of X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) has been used to study the crystal structure of molybdenum uranium pentoxide, UMoO5, obtained by hydrothermal and ceramic methods. Crystal data: Mr = 414.0, orthorhombic, Pbaa (number 54), a = 12.746 (1), b = 7.3494 (7), c = 4.1252 (2) Å, V = 386.4 (1) Å3, Z = 4, Dx = 7.116 Mg m−3, R = 0.037 for 723 reflections. The structure of UMoO5 is related to that of UVO5. Both are built up by slabs of pentagonal UO7 bipyramids with slabs of MO6 octahedra in-between. They differ in symmetry due to different types of displacement of the M atoms from the ab plane. The HRTEM study revealed a few defect regions in the UMoO5 crystals prepared by ceramic methods. Energy-dispersive spectroscopy (EDS) analyses indicate a slight excess of uranium in such crystals. Hypothetical models of defect regions are given.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Ideal and Real Structure of Ti5O4(PO4)4: X-ray and HRTEM Investigations

1998 ◽  
Vol 54 (6) ◽  
pp. 722-731 ◽  
Author(s):  
F. Reinauer ◽  
R. Glaum
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Structure Refinement ◽  
Ideal Structure ◽  
Crystal Data ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Ideal

The crystal structure of pentatitanium tetraoxide tetrakis(phosphate), Ti5O4(PO4)4, has been determined and refined from X-ray diffraction single-crystal data [P212121 (No. 19), Z = 4, a = 12.8417 (12), b = 14.4195 (13), c = 7.4622 (9) Å (from Guinier photographs); conventional residual R 1 = 0.042 for 2556 Fo > 4σ(Fo ), R 1 = 0.057 for all 3276 independent reflections; 282 parameters; 29 atoms in the asymmetric unit of the ideal structure]. The structure is closely related to those of β-Fe2O(PO4)-type phosphates and synthetic lipscombite, Fe3(PO4)4(OH). While these consist of infinite chains of face-sharing MO6 octahedra, in pentatitanium tetraoxide tetrakis(phosphate) only five-eighths of the octahedral voids are occupied according to □3Ti5O4(PO4)4. Four of the five independent Ti4+O6 show high radial distortion [1.72 ≤ d(Ti−O) ≤ 2.39 Å] and a typical 1 + 4 + 1 distance distribution. The fifth Ti4+O6 is an almost regular octahedron [1.91 ≤ d(Ti−O) ≤ 1.98 Å]. Partial disorder of Ti4+ over the available octahedral voids is revealed by the X-ray structure refinement. High-resolution transmission electron microscopy (HRTEM) investigations confirm this result.

Microstructural analysis of high-pressure compressed C60

2001 ◽  
Vol 16 (7) ◽  
pp. 1960-1966 ◽  
Author(s):  
K. Miyazawa ◽  
H. Satsuki ◽  
M. Kuwabara ◽  
M. Akaishi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Pressure ◽  
High Resolution ◽  
Microstructural Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hardness Tests ◽  
Lattice Planes

The structure and hardness of C60 bulk specimens compressed under 5.5 GPa at room temperature to 600 °C are investigated by high-resolution transmission electron microscopy, x-ray diffraction, and micro-Vickers hardness tests. A strong accumulation of the [1 1 0]tr orientation of high-pressure-treated C60 specimens was developed along the compression axis, and stacking faults and nano-sized deformation twins were introduced into the C60 specimens compressed at 450–600 °C. Curved lattice planes indicating a polymerization of C60 were observed by high resolution transmission electron microscopy (HRTEM). The polymerization of the high-pressure-compressed C60 is also supported by the computer simulation of HRTEM images.

Preparation and Luminescence Properties of ZnS: Cu/Fe Nanocrystalline

2014 ◽  
Vol 1033-1034 ◽  
pp. 1054-1057
Author(s):  
Xiang Zhang ◽  
Jin Liang Huang ◽  
Li Hua Li
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thioglycolic Acid ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zinc Blende ◽  
Transmission Electron ◽  
Fe Nanoparticles

ZnS: Cu/Fe nanocrystals were synthesized by hydrothermal method with thioglycolic acid as a stabilizer. The phases, grain size and luminescent properties of the nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fluorescence photometer respectively. The results showed that ZnS: Cu/Fe nanoparticles have a particle size about 7nm and possess a cubic zinc blende crystal structure. The luminous intensity of ZnS: Cu/Fe nanocrystals was strongly when they were reacted at 140°C for 12 hours.

Double Periodicity Formation in EuTe/PbTe Superlattices

1995 ◽  
Vol 399 ◽  
Author(s):  
M. Shima ◽  
L. Salamanca-Riba ◽  
G. Springholz ◽  
G. Bauer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices

ABSTRACTMolecular beam epitaxy was used to grow EuTe(x)/PbTe(y) short period superlattices with x=1-4 EuTe(111) monolayers alternating with y≈3x PbTe monolayers. The superlattices were characterized by transmission electron microscopy and high resolution x-ray diffraction. Regions with double periodicity were observed coexisting with areas of nominal periodicity. The sample with x=3.5 and y=9, for example, contains regions with double periodicity of x=7 and y=17. X-ray diffraction measurements confirm the formation of the double periodicity in these samples by the appearance of weak satellites in between the satellites of the nominal periodicity. The double periodicity in the superlattice is believed to result from interdiffusion during the growth. A model for this process is presented.

FABRICATION AND CHARACTERISTICS OF ALN NANOWIRES

2001 ◽  
Vol 15 (30) ◽  
pp. 1455-1458 ◽  
Author(s):  
H. CHEN ◽  
X. K. LU ◽  
S. Q. ZHOU ◽  
X. H. HAO ◽  
Z. X. WANG
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Sublimation Method ◽  
Scanning Electron

Single phase AlN nanowires are fabricated by a sublimation method. They were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), typical selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The SEM and TEM images show that most of the nanowires have diameters of about 10–60 nm. The crystal structure of AlN nanowires revealed by XRD, SAED and HRTEM shows the AlN nanowires have a wurtzite structure.

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