Commensurate-Glass Phase Transitions in Staged Sbcl5-GIC

1982 ◽  
Vol 20 ◽  
Author(s):  
L. Salamanca-Riba ◽  
G. Timp ◽  
L.W. Hobbs ◽  
M.S. Dresselhaus
Keyword(s):  
Phase Transition ◽  
Experimental Study ◽  
Glass Transition ◽  
Phase Transitions ◽  
Electron Diffraction ◽  
Low Temperatures ◽  
Glass Phase ◽  
Driving Mechanism ◽  
X Ray Diffraction ◽  
X Ray

ABSTRACTAn experimental study is reported of the commensurate (√7 × √7)R19.1° to glass phase transition in stages I < n > 4 graphite-SbCl5 using electron and x-ray diffraction. The electron diffraction studies show an in-plane phase transition to a glass at low temperatures. The (00l) x-ray diffraction scans show that the c-axis layered structure of the intercalate is unchanged by the phase transition. A driving mechanism for the commensurate to glass transition is suggested.

Structural-phase transition in (Cu2Te)2−x(ZnTe)x at high temperature

2021 ◽  
pp. 2150113
Author(s):  
H. B. Gasimov ◽  
R. M. Rzayev
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
High Temperature ◽  
Single Crystals ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Range ◽  
Xrd Study ◽  
Xrd Method

Cu2Te single crystal was grown by the Bridgman method. X-ray diffraction (XRD) study of Cu2Te single crystals in the temperature range of 293–893 K was performed and possible phase transitions in the mentioned range of temperature have been investigated. (Cu2Te)[Formula: see text](ZnTe)[Formula: see text] single crystals also were grown with [Formula: see text], 0.05, 0.10 concentrations and structural properties of the obtained single crystals were investigated by the XRD method in the temperature range 293–893 K. Lattice parameters and possible phase transitions in the mention temperature range were determined for (Cu2Te)[Formula: see text](ZnTe)[Formula: see text] single crystals for [Formula: see text], 0.05, 0.10 concentrations.

X-ray diffraction and Raman study of DL-alanine at high pressure: revision of phase transitions

2012 ◽  
Vol 68 (4) ◽  
pp. 412-423 ◽  
Author(s):  
Nikolay A. Tumanov ◽  
Elena V. Boldyreva
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Structural Phase ◽  
Group Symmetry ◽  
Second Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Raman Study

The effect of pressure on DL-alanine has been studied by X-ray powder diffraction (up to 8.3 GPa), single-crystal X-ray diffraction and Raman spectroscopy (up to ∼ 6 GPa). No structural phase transitions have been observed. At ∼ 1.5–2 GPa, cell parameters b and c become accidentally equal to each other, but the space-group symmetry does not change. There is no phase transition between 1.7 and 2.3 GPa, contrary to what has been reported earlier [Belo et al. (2010). Vibr. Spectrosc. 54, 107–111]. The presence of the second phase transition, which was claimed to appear within the pressure range from 6.0 to 7.3 GPa (Belo et al., 2010), is also argued. The changes in the Raman spectra have been shown to be continuous in all the pressure ranges studied.

Investigation of the structure and phase transitions of the polymeric inorganic–organic hybrids: [M(Im)4V2O6]∞; M = Mn, Co, Ni, Im = imidazole

2010 ◽  
Vol 67 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Kittipong Chainok ◽  
Kenneth J. Haller ◽  
A. David Rae ◽  
Anthony C. Willis ◽  
Ian D. Williams
Keyword(s):  
Phase Transition ◽  
Low Temperatures ◽  
Stacking Faults ◽  
Local Geometry ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Disordered Phase ◽  
Large Hysteresis ◽  
Close Proximity

The polymeric isomorphous hybrid inorganic–organic vanadium oxide compounds [M(Im)4V2O6]∞, M = Mn, Co, Ni, Im = imidazole, were investigated at various temperatures between 100 and 295 K by single-crystal X-ray diffraction. The crystals all contain two-dimensional polymeric sheets packed perpendicular to c* and are 1:1 disordered in the space group P42/n (Z = 8) at 295 K. The disordered phase is reversibly transformed to an I41/a ordered phase (Z = 32) below 281 K for the Mn compound and below 175 K for the Co compound. Within a localized region of the I41/a phase eight imidazoles are in close proximity and seven of these are hydrogen bonded to framework O atoms. The hydrogen-bond connectivity of six of these ligands is unchanged by the phase transition that allows an inversion of the local geometry using an inversion operator that is a symmetry element of P42/n, but not I41/a. The Mn structure has a well defined phase transition but the Co structure shows a large hysteresis and it was necessary to include stacking faults in the modelling of the Co structure at low temperatures. The Ni structure was shown to be partially twinned, but ordered in the space group P2/n (Z = 8) at 100 K, with two different localized regions each containing four pairs of inversion-related imidazoles, hydrogen bonding to framework O atoms involving eight imidazoles in one region and six imidazoles in the other. Models for the phase transition mechanisms are considered.

Investigation of Phase Transitions in Stacked GeTe/SnTe and Ge2Se3/SnTe Chalcogenide Films

2011 ◽  
Vol 687 ◽  
pp. 677-683 ◽  
Author(s):  
Fei Ming Bai ◽  
Huai Wu Zhang ◽  
Surendra Gupta ◽  
Santosh Kurinec
Keyword(s):  
Phase Transition ◽  
Solid Solution ◽  
Phase Transitions ◽  
Phase Change Memory ◽  
Thin Layers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Area Detector ◽  
Memory Applications ◽  
Change Memory

Phase transitions in stacked GeTe/SnTe and Ge2Se3/SnTe thin layers for potential phase-change memory applications have been investigated by X-ray diffraction using an area detector system and by scanning electron microscopy. The as-deposited underlying GeTe or Ge2Se3 layer is amorphous, whereas the top SnTe layer is crystalline. In GeTe/SnTe stack, the crystallization of GeTe phase occurs near 170°C, and upon further heating, GeTe phase disappears, followed by the formation of rocksalt-structured GexSn1-xTe solid solution. In Ge2Se3/SnTe stack, the phase transition starts with the separation of SnSe phase due to the migration of Sn ions into the Ge2Se3 layer. The migration of Sn ions and the formation of SnSe are believed to facilitate the crystallization of Ge2Se3 solid solution at ~360°C, which is much lower than the crystallization temperature of Ge2Se3, therefore consuming less power during the phase transition.

Single Crystal X-Ray Diffraction Study of the Phase Transitions in Graphite-Bromine Intercalation Compounds

1982 ◽  
Vol 20 ◽  
Author(s):  
D. Ghosh ◽  
D.D.L. Chung
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Diffraction Study ◽  
Structure Characteristic ◽  
Q Value ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stage 4 ◽  
Commensurate Phase ◽  
Bromine Vapor

ABSTRACTReported here is the first observation of an incommensurate-commensurate phase transition at 316 ± 1 K upon heating stage-2 graphite-bromine prepared in bromine liquid. The transition during heating involved the movement of the 300 reflection toward a lower q value and the sharpening of the 010 reflection, thereby resulting in the commensurate structure characteristic of stage-2 prepared in bromine vapor. The transition was reversible. The previously reported comtmensurate-incommensurate transition occurred at 326, 329, 332, 338 and 348 K for stage 2 (in bromine liquid), stage 2 (in bromine vapor), stage 3, stage 4, and desorbed material, respectively. Disordering was observed upon completion of this transition.

scholarly journals Inorganic Anion Regulates the Phase Transition in Two Organic Cation Salts Containing [(4-Nitroanilinium)(18-crown-6)]+ Supramolecules

2017 ◽  
Author(s):  
Yuan Chen ◽  
Yang Liu ◽  
Binzu Gao ◽  
Chuli Zhu ◽  
Zunqi Liu
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Variable Temperature ◽  
Structural Phase ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Space Group ◽  
X Ray

Two novel inorganic&ndash;organic hybrid supramolecular assemblies, namely, (4-HNA)(18-crown-6)(HSO4) (1) and (4-HNA)2(18-crown-6)2(PF6)2(CH3OH) (2) (4-HNA = 4-nitroanilinium), were synthesized and characterized by infrared spectroscopy, single X-ray diffraction, differential scanning calorimetry (DSC), and temperature-dependent dielectric measurements. The two compounds underwent reversible phase transitions at about 255 K and 265 K, respectively. These phase transitions were revealed and confirmed by the thermal anomalies in DSC measurements and abrupt dielectric anomalies during heating. The phase transition may have originated from the [(4-HNA)(18-crown-6)]+ supramolecular cation. The inorganic anions tuned the crystal packings and thus influenced the phase-transition points and types. The variable-temperature X-ray diffraction data for crystal 1 revealed the occurrence of a phase transition in the high-temperature phase with the space group of P21/c and in the low-temperature phase with the space group of P21/n. Crystal 2 exhibited the same space group P21/c at different temperatures. The results indicated that crystals 1 and 2 both underwent an iso-structural phase transition.

Disorder in crystals of dioxofluorotungstates, (NH4)2WO2F4 and Rb2WO2F4

2008 ◽  
Vol 64 (6) ◽  
pp. 645-651 ◽  
Author(s):  
Anatoly A. Udovenko ◽  
Natalia M. Laptash
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Symmetry Axis ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Twin Structure ◽  
Static Disorder ◽  
X Ray ◽  
Independent States ◽  
Lower Temperature

Dioxotetrafluorotungstates (NH4)2WO2F4 [(I) at 297 K and (II) at 133 K] and Rb2WO2F4 (III) were synthesized in a single-crystal form and their structures were determined by X-ray diffraction. Two independent states of the cis-WO2F4 octahedron are characteristic of static and dynamic disorder in structure (I). Dynamically disordered W2 is displaced from the symmetry axis producing four possible orientations of anion that permits O and F atoms to be identified in separate orientations owing to the inherent differences between W—O and W—F bonding. After the phase transition at lower temperature (201 K), (I) transforms into the twin structure (II) with complete O/F ordering. Structure (III) is characterized by full O/F static disorder without any phase transitions at lower temperature.

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