Powder X-ray diffraction studies of a low-temperature phase transition in the n-hexadecane/urea inclusion compound

1990 ◽  
Vol 86 (18) ◽  
pp. 3135 ◽  
Author(s):  
Kenneth D. M. Harris ◽  
Ian Gameson ◽  
John M. Thomas
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Inclusion Compound ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Phase Transition ◽  
Urea Inclusion Compound ◽  
Urea Inclusion ◽  
Low Temperature Phase

X-ray diffraction study of the phase transition of K2Mn2(BeF4)3: a new type of low-temperature structure for langbeinites

2001 ◽  
Vol 57 (3) ◽  
pp. 221-230 ◽  
Author(s):  
A. Guelylah ◽  
G. Madariaga ◽  
V. Petricek ◽  
T. Breczewski ◽  
M. I. Aroyo ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Mode Analysis ◽  
Cubic Phase ◽  
Temperature Phase ◽  
Temperature Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Type ◽  
Low Temperature Phase

The potassium manganese tetrafluoroberyllate langbeinite compound has been studied in the temperature range 100–300 K. Using DSC measurements, a phase transition has been detected at 213 K. The space group of the low-temperature phase was determined to be P1121 using X-ray diffraction experiments and optical observations of the domain structure. The b axis is doubled with respect to the prototypic P213 cubic phase. Lattice parameters were determined by powder diffraction data [a = 10.0690 (8), b = 20.136 (2), c = 10.0329 (4) Å, γ = 90.01 (1)°]. A precise analysis of the BeF4 tetrahedra in the low-temperature phase shows that two independent tetrahedra rotate in opposite directions along the doubled crystallographic axis. A symmetry mode analysis of the monoclinic distortion is also reported. This is the first report of the existence of such a phase transition in K2Mn2(BeF4)3 and also of a new type of low-temperature structure for langbeinite compounds.

X-ray study of the low-temperature phase transition in K2CoCl4

1996 ◽  
Vol 56 (3) ◽  
pp. 147-152 ◽  
Author(s):  
J. Kusz ◽  
A. Pietraszko ◽  
J. Warczewski
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Temperature Phase ◽  
X Ray ◽  
Temperature Phase Transition ◽  
Low Temperature Phase

Phase Transitions and Distortion of [BiCl6]3– Octahedra in (C3H5NH3)3[BiCl6] – DSC and Single-Crystal X-Ray Diffraction Studies

2004 ◽  
Vol 59 (9) ◽  
pp. 1029-1034 ◽  
Author(s):  
Bartosz Zarychta ◽  
Maciej Bujak ◽  
Jacek Zaleski
Keyword(s):  
Phase Transition ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Unit Cells ◽  
Temperature Phase Transition ◽  
The Relationship ◽  
Low Temperature Phase ◽  
Disorder Type

The DSC diagram of tris(allylammonium) hexachlorobismuthate(III), (C3H5NH3)3[BiCl6], revealed three anomalies at 152, 191 and 299 K. The structure of the salt was determined at 200 and 315 K, below and above the high-temperature phase transition at 299 K. In both phases the crystals are monoclinic. At 200 K the space group is C2/c whereas at 315 K it is C2/m. The structures, at both temperatures, are composed of [BiCl6]3− octahedra and allylammonium cations. The organic and inorganic moieties are attracted to each other by a network of the N-H. . .Cl hydrogen bonds. The relationship between corresponding parameters of the unit cells has been found. The phase transition at 299 K, of the order-disorder type, is attributed to the ordering of one non-equivalent allylammonium cation in the low-temperature phase.

NQR View of Solid Phases of NOCl

1998 ◽  
Vol 53 (6-7) ◽  
pp. 537-541 ◽  
Author(s):  
J. Pirnat ◽  
Z. Trontelj ◽  
H. Borrmann
Keyword(s):  
Phase Transition ◽  
Temperature Phase ◽  
Measured Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Disorder Phase Transition ◽  
Upper Limit ◽  
Temperature Phase Transition ◽  
Solid Phases ◽  
Low Temperature Phase

Abstract Chlorine NQR studies of solid nitrosyl chloride NOC1 between 110 and 212 K are reported. In the temperature dependence an order-disorder phase transition near 145 K, found by X-ray diffraction, is confirmed. Unusual hysteretic NQR signal behaviour indirectly proves also the low temperature phase transition below 100 K. In the measured temperature region fast relaxing mechanisms are present. The upper limit of the expected 14N NQR frequency is estimated using the Townes-Dailey approach.

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