Structure determination of the low-temperature phase of tertiary butyl cyanide by the constrained profile refinement of the powder diffraction pattern

1982 ◽  
Vol 78 (1) ◽  
pp. 179 ◽  
Author(s):  
Jonathan C. Frost ◽  
Alan J. Leadbetter ◽  
Robert M. Richardson ◽  
Richard C. Ward ◽  
John W. Goodby ◽  
...  
Keyword(s):  
Low Temperature ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Structure Determination ◽  
Temperature Phase ◽  
Tertiary Butyl ◽  
Low Temperature Phase ◽  
Profile Refinement

Low Temperature Phase of NaOD

1986 ◽  
Vol 41 (1-2) ◽  
pp. 283-285 ◽  
Author(s):  
T. J. Bastow ◽  
D. T. Amm ◽  
S. W. Segel ◽  
R. D. Heyding
Keyword(s):  
Low Temperature ◽  
Powder Diffraction ◽  
Temperature Phase ◽  
X Ray ◽  
New Phase ◽  
Low Temperature Phase

The existence of a new phase of NaOD below 160 K is reported. NQR, NMR and DTA spectra are given and preliminary X-ray powder diffraction measurements are discussed.

scholarly journals Evidence from Fermi surface analysis for the low-temperature structure of lithium

2017 ◽  
Vol 114 (21) ◽  
pp. 5389-5394 ◽  
Author(s):  
Sabri F. Elatresh ◽  
Weizhao Cai ◽  
N. W. Ashcroft ◽  
Roald Hoffmann ◽  
Shanti Deemyad ◽  
...  
Keyword(s):  
Low Temperature ◽  
Fermi Surface ◽  
Alkali Metals ◽  
Ambient Pressure ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Low Temperature Crystal Structure ◽  
Temperature Phase Transition ◽  
Low Temperature Phase

The low-temperature crystal structure of elemental lithium, the prototypical simple metal, is a several-decades-old problem. At 1 atm pressure and 298 K, Li forms a body-centered cubic lattice, which is common to all alkali metals. However, a low-temperature phase transition was experimentally detected to a structure initially identified as having the 9R stacking. This structure, proposed by Overhauser in 1984, has been questioned repeatedly but has not been confirmed. Here we present a theoretical analysis of the Fermi surface of lithium in several relevant structures. We demonstrate that experimental measurements of the Fermi surface based on the de Haas–van Alphen effect can be used as a diagnostic method to investigate the low-temperature phase diagram of lithium. This approach may overcome the limitations of X-ray and neutron diffraction techniques and makes possible, in principle, the determination of the lithium low-temperature structure (and that of other metals) at both ambient and high pressure. The theoretical results are compared with existing low-temperature ambient pressure experimental data, which are shown to be inconsistent with a 9R phase for the low-temperature structure of lithium.

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