The Effect of the Electron Density Anisotropy on Positron Annihilation in a KBr single Crystal

1972 ◽  
Vol 7 (7) ◽  
pp. 841-844 ◽  
Author(s):  
K. P. Arefiev ◽  
S. A. Vorobiev
Keyword(s):  
Single Crystal ◽  
Positron Annihilation ◽  
Electron Density

scholarly journals Crystallographic features of ammonium fluoroelpasolites: dynamic orientational disorder in crystals of (NH4)3HfF7 and (NH4)3Ti(O2)F5

2017 ◽  
Vol 73 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Anatoly A. Udovenko ◽  
Alexander A. Karabtsov ◽  
Natalia M. Laptash
Keyword(s):  
Single Crystal ◽  
Electron Density ◽  
Diffraction Data ◽  
Central Atom ◽  
X Ray Diffraction ◽  
Dynamic Nature ◽  
Orientational Disorder ◽  
High Quality ◽  
Structural Units ◽  
X Ray

A classical elpasolite-type structure is considered with respect to dynamically disordered ammonium fluoro-(oxofluoro-)metallates. Single-crystal X-ray diffraction data from high quality (NH4)3HfF7 and (NH4)3Ti(O2)F5 samples enabled the refinement of the ligand and cationic positions in the cubic Fm \bar 3 m (Z = 4) structure. Electron-density atomic profiles show that the ligand atoms are distributed in a mixed (split) position instead of 24e. One of the ammonium groups is disordered near 8c so that its central atom (N1) forms a tetrahedron with vertexes in 32f. However, a center of another group (N2) remains in the 4b site, whereas its H atoms (H2) occupy the 96k positions instead of 24e and, together with the H3 atom in the 32f position, they form eight spatial orientations of the ammonium group. It is a common feature of all ammonium fluoroelpasolites with orientational disorder of structural units of a dynamic nature.

Imaging of Electron Density Distribution of CeP Under High Pressure by Single Crystal SR X-Ray Experiments

2001 ◽  
Vol 70 (4) ◽  
pp. 1162-1163 ◽  
Author(s):  
Takahisa Shobu ◽  
Yukio Noda ◽  
Kazuaki Iwasa ◽  
Abdul Hannan ◽  
Masahumi Kohgi ◽  
...  
Keyword(s):  
High Pressure ◽  
Density Distribution ◽  
Single Crystal ◽  
Electron Density ◽  
Electron Density Distribution ◽  
X Ray

Positron annihilation spectroscopy of proton irradiated single crystal BCC iron

2006 ◽  
Vol 351 (1-3) ◽  
pp. 149-154 ◽  
Author(s):  
Maria A. Okuniewski ◽  
Doug P. Wells ◽  
Farida A. Selim ◽  
Stuart A. Maloy ◽  
Michael R. James ◽  
...  
Keyword(s):  
Single Crystal ◽  
Positron Annihilation ◽  
Positron Annihilation Spectroscopy ◽  
Bcc Iron

Positron Annihilation in a Neutron Irradiated α-Al2O3 Single Crystal

1994 ◽  
Vol 175-178 ◽  
pp. 461-464 ◽  
Author(s):  
Yasuyuki Nagashima ◽  
K. Kawashima ◽  
Takeo Hyodo ◽  
Masuyuki Hasegawa ◽  
B.T. Lee ◽  
...  
Keyword(s):  
Single Crystal ◽  
Positron Annihilation
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