ChemInform Abstract: Structure Determination of a Low Temperature Phase of Calcium and Strontium Amide by Means of Neutron Powder Diffraction on Ca(ND2)2 and Sr(ND2)2.

ChemInform ◽  
2010 ◽  
Vol 31 (12) ◽  
pp. no-no
Author(s):  
J. Senker ◽  
H. Jacobs ◽  
M. Mueller ◽  
W. Press ◽  
H. M. Mayer ◽  
...  
Keyword(s):  
Low Temperature ◽  
Powder Diffraction ◽  
Structure Determination ◽  
Neutron Powder Diffraction ◽  
Temperature Phase ◽  
Abstract Structure ◽  
Low Temperature Phase

ChemInform Abstract: Structure Determination of Ba(OD)Br×2 D2O by Neutron Powder Diffraction.

ChemInform ◽  
2010 ◽  
Vol 22 (22) ◽  
pp. no-no
Author(s):  
T. KELLERSOHN ◽  
K. BECKENKAMP ◽  
H. D. LUTZ ◽  
E. JANSEN
Keyword(s):  
Powder Diffraction ◽  
Structure Determination ◽  
Neutron Powder Diffraction ◽  
Abstract Structure

Alloxan—a new low-temperature phase determined by neutron powder diffraction

CrystEngComm ◽  
2008 ◽  
Vol 10 (5) ◽  
pp. 465 ◽  
Author(s):  
Richard M. Ibberson ◽  
William G. Marshall ◽  
Laura E. Budd ◽  
Simon Parsons ◽  
Colin R. Pulham ◽  
...  
Keyword(s):  
Low Temperature ◽  
Powder Diffraction ◽  
Neutron Powder Diffraction ◽  
Temperature Phase ◽  
Low Temperature Phase

Temperature-dependent neutron powder diffraction study of the Ba(OD)2 polymorphs: a new low-temperature phase

2001 ◽  
Vol 57 (6) ◽  
pp. 747-758 ◽  
Author(s):  
Alexandra Friedrich ◽  
Martin Kunz ◽  
Emmanuelle Suard
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Powder Diffraction ◽  
Metastable Phase ◽  
Neutron Powder Diffraction ◽  
Group Symmetry ◽  
Mirror Plane ◽  
Temperature Phase ◽  
Α Phase ◽  
Low Temperature Phase

The structural behaviour of both low-temperature β- and high-temperature α-Ba(OD)2, barium dihydroxide-d, was investigated at temperatures between 10 and 552 K by neutron powder diffraction. While the β phase (P21/n) remains stable to the lowest temperature investigated, the quenchable α phase (Pnma) shows a reversible orthorhombic-to-monoclinic phase transition between 100 and 150 K. The structure of the new α m phase (P21/n) is quite similar to that of the α phase. This behaviour is unusual as a metastable phase transforms to another metastable phase. The Pnma ↔ P21/n low-temperature phase transition is driven by an order–disorder mechanism, mainly caused by one of the D atoms, which is disordered on positions off the mirror plane, mimicking a special position on the mirror plane in the orthorhombic phase. Refinements of the α phase above the phase transition indicate this disorder across the mirror plane through a conspicuously high isotropic displacement parameter if compared to the other D atoms. At low temperature the energy of the vibration is lowered and the D atom is frozen at a general position in a correlated way, thus violating the mirror plane and reducing the space-group symmetry.

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