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.

scholarly journals High-temperature phase transition of SrRuO3and SrHfO5: X-ray diffraction and PAC spectroscopy

1996 ◽  
Vol 52 (a1) ◽  
pp. C364-C364
Author(s):  
J. A. Guevara ◽  
S. L. Cuffini ◽  
Y. P. Mascarenhas ◽  
P. de la Presa ◽  
A. Ayala ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Pac Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Phase Transition

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.

Characterization of the time-dependentL-asparagine monohydrate crystal phase transition

2011 ◽  
Vol 44 (5) ◽  
pp. 954-957 ◽  
Author(s):  
A. S. de Menezes ◽  
F. M. Ardito ◽  
A. O. dos Santos ◽  
A. J. D. Moreno ◽  
R. J. C. Lima ◽  
...  
Keyword(s):  
Phase Transition ◽  
Annealing Time ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Temperature Phase Transition ◽  
Asparagine Monohydrate

The high-temperature phase transition of single crystals of L-asparagine monohydrate was investigated by X-ray diffraction in association with Rietveld refinement and dilatometer measurements as a function of annealing time. The X-ray results showed that, for samples annealed at 343 K (or even 333 K) for 5 h, the expected anhydrous L-asparagine phase has been formed, monoclinic system (space groupP21), with lattice parametersa= 5.0677 (2),b= 6.7657 (2),c = 8.0742 (3) Å and β = 91.276 (4)°. The results obtained from measurements as a function of annealing time confirmed that the phase transition associated with loss of the water molecule is time dependent.

On the Phase Transition of Bis(pyridinium)hexachlorometallates, (C5H5NH)2[MCl6], M = Sn, Te, Pb, Pt. An X-Ray and 35Cl NQR Study

1987 ◽  
Vol 42 (7) ◽  
pp. 739-748 ◽  
Author(s):  
Dirk Borchers ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Phase Ii ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray ◽  
Lattice Constants ◽  
Pyridinium Ring ◽  
35Cl Nqr ◽  
Low Temperature Phase

A phase transition has been observed in bis(pyridinium) hexachlorometallates (C5H5NH)2[MIVCl6]. M = Sn. Te. Pb. Pt. The crystal structure of the low temperature phase II of the salt with M = Sn was determined, space group C 1ḷ- P 1̅, Z = 1 (a = 734.1pm, b = 799.0 pm, c = 799.7 pm,α= 83.229°. β = 65.377°, γ= 84.387°, T = 297 K). The four compounds are isotypic in phase II as well as in the high temperature phase I (C2H2-B2 /m, Z = 2) for which the crystal structure is known for M = Te . The lattice constants of all compounds (both phases) are given. The temperature dependence of the 35Cl NQR spectrum was investigated. The three line 35Cl NQR spectrum is in agreement with the crystal structure. The dynamics of the pyridinium ring shows up in a fade out of part of the 35Cl NQR spectrum . The influence o f H ↔ D exchange on 35Cl NQR is studied and an assignment of ν (35Cl) ↔ Cl(i) is proposed. The nature of the phase transition P1̅ (Z = 1) ↔ B2 /m (Z = 2) is discussed.

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.

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