Phase Transition from Low-Temperature Normal Phase to High-Temperature Superionic Phase in The Cu2-x Se System Studied by Means of X-Ray Diffraction

1981 ◽  
pp. 337-342 ◽  
Author(s):  
A. Tonejc
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Low Temperature ◽  
Normal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Superionic Phase

scholarly journals From space group to space groupoid: the partial symmetry of low-temperature E-vanillyl oxime

2019 ◽  
Vol 75 (4) ◽  
pp. 733-741
Author(s):  
Katharina Ehrmann ◽  
Stefan Baudis ◽  
Berthold Stöger
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Low Temperature ◽  
Euclidean Space ◽  
Single Crystal ◽  
Connected Components ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Full Symmetry

The phase transition of E-vanillyl oxime {1-[(E)-(hydroxyimino)methyl]-4-hydroxy-3-methoxybenzene, C8H9NO3} has been analysed by single-crystal and powder X-ray diffraction. The high-temperature (HT) phase (P21/a, Z′ = 1) transforms into the low-temperature (LT) phase (threefold superstructure, P\overline{1}, Z′ = 6) at ca 190 K. The point operations lost on cooling, {m [010], 2[010]}, are retained as twin operations and constitute the twin law. The screw rotations and glide reflections are retained in the LT phase as partial operations acting on a subset of Euclidean space {\bb E}^3. The full symmetry of the LT phase, including partial operations, is described by a disconnected space groupoid which is built of three connected components.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

scholarly journals X-ray diffraction analysis of kaolin M1 and M2 via the Williamson–Hall and Warren–Averbach methods

2021 ◽  
pp. 174751982098472
Author(s):  
Lalmi Khier ◽  
Lakel Abdelghani ◽  
Belahssen Okba ◽  
Djamel Maouche ◽  
Lakel Said
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Low Temperature ◽  
Diffraction Analysis ◽  
Mechanical Resistance ◽  
X Ray Diffraction ◽  
Integral Breadth ◽  
X Ray ◽  
Mullite Phase

Kaolin M1 and M2 studied by X-ray diffraction focus on the mullite phase, which is the main phase present in both products. The Williamson–Hall and Warren–Averbach methods for determining the crystallite size and microstrains of integral breadth β are calculated by the FullProf program. The integral breadth ( β) is a mixture resulting from the microstrains and size effect, so this should be taken into account during the calculation. The Williamson–Hall chart determines whether the sample is affected by grain size or microstrain. It appears very clearly that the principal phase of the various sintered kaolins, mullite, is free from internal microstrains. It is the case of the mixtures fritted at low temperature (1200 °C) during 1 h and also the case of the mixtures of the type chamotte cooks with 1350 °C during very long times (several weeks). This result is very significant as it gives an element of explanation to a very significant quality of mullite: its mechanical resistance during uses at high temperature remains.

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

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.

Analysis of phase transition behavior of BaCeO3 with thermal analyses and high temperature X-ray diffraction

2009 ◽  
Vol 180 (17-19) ◽  
pp. 1034-1039 ◽  
Author(s):  
Takeshi Ohzeki ◽  
Shinya Hasegawa ◽  
Misa Shimizu ◽  
Takuya Hashimoto
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Thermal Analyses ◽  
X Ray Diffraction ◽  
Phase Transition Behavior ◽  
X Ray ◽  
Transition Behavior

Structural chemistry of NaCoPO4

1996 ◽  
Vol 52 (3) ◽  
pp. 440-449 ◽  
Author(s):  
R. Hammond ◽  
J. Barbier
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Large Family ◽  
X Ray Diffraction ◽  
Tetrahedral Framework ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Tetrahedral Sites ◽  
Bond Valence Analysis

Sodium cobalt phosphate, NaCoPO4, occurs as two different polymorphs which transform reversibly at 998 K. The crystal structures of both polymorphs have been determined by single-crystal X-ray diffraction. The low-temperature form α-NaCoPO4 crystallizes in the space group Pnma with cell parameters: a = 8.871 (3), b = 6.780 (3), c = 5.023 (1) Å, and Z = 4 [wR(F 2) = 0.0653 for all 945 independent reflections]. The α-phase contains octahedrally coordinated Co and Na atoms and tetrahedrally coordinated P atoms, and is isostructural with maracite, NaMnPO4. The structure of high-temperature β-NaCoPO4 is hexagonal with space group P65 and cell parameters: a = 10.166 (1), c = 23.881 (5) Å, and Z = 24 [wR(F 2) = 0.0867 for 4343 unique reflections]. The β-phase belongs to the large family of stuffed tridymites, with the P and Co atoms occupying tetrahedral sites and the Na atoms located in the cavities of the tetrahedral framework. The long c axis corresponds to a 3 × superstructure of the basic tridymite framework (c ≃ 8 Å) and is caused by the displacement of the Na atoms, tetrahedral tilts and strong distortions of the CoO4 tetrahedra. A bond-valence analysis of these phases reveals that the polymorphism in NaCoPO4 is due in part to over-/underbonding of the Na atom in the low-/high-temperature structures, respectively.

A conformational polymorphic transition in the high-temperature ∊-form of chlorpropamide on cooling: a new ∊′-form

2009 ◽  
Vol 65 (6) ◽  
pp. 770-781 ◽  
Author(s):  
Tatiana N. Drebushchak ◽  
Yury A. Chesalov ◽  
Elena V. Boldyreva
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Structural Changes ◽  
Molecular Conformation ◽  
Polymorphic Transition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Temperature Range ◽  
Two Phases

Structural changes in the high-temperature ∊-polymorph of chlorpropamide, 4-chloro-N-(propylaminocarbonyl)benzenesulfonamide, C10H13ClN2O3S, on cooling down to 100 K and on reverse heating were followed by single-crystal X-ray diffraction. At temperatures below 200 K the phase transition into a new polymorph (termed the ∊′-form) has been observed for the first time. The polymorphic transition preserves the space group Pna21, is reversible and is accompanied by discontinuous changes in the cell volume and parameters, resulting from changes in molecular conformation. As shown by IR spectroscopy and X-ray powder diffraction, the phase transition in a powder sample is inhomogeneous throughout the bulk, and the two phases co-exist in a wide temperature range. The cell parameters and the molecular conformation in the new polymorph are close to those in the previously known α-polymorph, but the packing of the z-shaped molecular ribbons linked by hydrogen bonds inherits that of the ∊-form and is different from the packing in the α-polymorph. A structural study of the α-polymorph in the same temperature range has revealed no phase transitions.

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