Revision of the Li–Si Phase Diagram: Discovery and Single-Crystal X-ray Structure Determination of the High-Temperature Phase Li4.11Si

2013 ◽  
Vol 25 (22) ◽  
pp. 4623-4632 ◽  
Author(s):  
Michael Zeilinger ◽  
Iryna M. Kurylyshyn ◽  
Ulrich Häussermann ◽  
Thomas F. Fässler
Keyword(s):  
Phase Diagram ◽  
High Temperature ◽  
Single Crystal ◽  
Structure Determination ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray

High-temperature single-crystal X-ray diffraction study of tetragonal and cubic perovskite-type PbTiO3phases

2016 ◽  
Vol 72 (3) ◽  
pp. 381-388 ◽  
Author(s):  
Akira Yoshiasa ◽  
Tomotaka Nakatani ◽  
Akihiko Nakatsuka ◽  
Maki Okube ◽  
Kazumasa Sugiyama ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Single Crystal ◽  
Diffraction Study ◽  
Relative Displacement ◽  
High Temperature Phase ◽  
Cubic Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray

A high-temperature single-crystal X-ray diffraction study of a synthetic PbTiO3perovskite was carried out over the wide temperature range 298–928 K. A transition from a tetragonal (P4mm) to a cubic (Pm \bar 3 m) phase has been revealed near 753 K. In the non-centrosymmetricP4mmsymmetry group, the difference in relative displacement between Pb and O along thec-axis is much larger than that between Ti and O. The Pb and Ti cations contribute sufficiently to polarization being shifted in the opposite direction compared with the shift of O atoms. Deviation from the linear changes in Debye–Waller factors and bonding distances in the tetragonal phases can be interpreted as a precursor phenomenon before the phase transition. Disturbance of the temperature factorUeqfor O is observed in the vicinity of the transition point, whileUeqvalues for Pb and Ti are continuously changing with increasing temperature. The O site includes the clear configurational disorder in the cubic phase. The polar local positional distortions remain in the cubic phase and are regarded as the cause of the paraelectricity. Estimated values of the Debye temperature ΘDfor Pb and Ti are 154 and 467 K in the tetragonal phase and decrease 22% in the high-temperature phase. Effective potentials for Pb and Ti change significantly and become soft after the phase transition.

scholarly journals Notizen: The Crystal Structure of β-CsReO4, the Room-Temperature Modification of Cesium Perrhenate

1993 ◽  
Vol 48 (5) ◽  
pp. 685-687 ◽  
Author(s):  
Peter Rögner ◽  
Klaus-Jürgen Range
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Single Crystal ◽  
Room Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Orthorhombic Distortion ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Cs Ions

The crystal structure of β-CsReO4, the roomtemperature modification of cesium perrhenate, was determined from single-crystal X-ray data as orthorhombic, space group P nma, a = 5.7556(9), b = 5.9964(8), c = 14.310(2) Å and Z = 4.The structure was refined to R = 0.027, Rw = 0.023 for 779 absorption-corrected reflections. It represents an orthorhombic distortion of the tetragonal high-temperature phase α-CsReO4. The structure of β-CsReO4 comprises isolated ReO4 tetrahedra, linked together by Cs ions. The average Re-O distance was found to be 1.714(4) Å.

Ab initio structure determination of the high-temperature phase of anhydrous caffeine by X-ray powder diffraction

2005 ◽  
Vol 61 (3) ◽  
pp. 329-334 ◽  
Author(s):  
Patrick Derollez ◽  
Natália T. Correia ◽  
Florence Danède ◽  
Frédéric Capet ◽  
Frédéric Affouard ◽  
...  
Keyword(s):  
High Temperature ◽  
Phase I ◽  
Metastable State ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Ab Initio Structure

The high-temperature phase I of anhydrous caffeine was obtained by heating and annealing the purified commercial form II at 450 K. This phase I can be maintained at low temperature in a metastable state. A powder X-ray diffraction pattern was recorded at 278 K with a laboratory diffractometer equipped with an INEL curved position-sensitive detector CPS120. Phase I is dynamically orientationally disordered (the so-called plastic phase). The Rietveld refinements were achieved with rigid-body constraints. It was assumed that on each site, a molecule can adopt three preferential orientations with equal occupation probability. Under a deep undercooling of phase I, below 250 K, the metastable state enters in a glassy crystal state.

High-temperature phase equilibria in the system Zr–O–N

2006 ◽  
Vol 21 (2) ◽  
pp. 320-328 ◽  
Author(s):  
Alexandre Ermoline ◽  
Mirko Schoenitz ◽  
Edward L. Dreizin
Keyword(s):  
Phase Diagram ◽  
High Temperature ◽  
Invariant Point ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Comparison Of The Results ◽  
Laser Heated ◽  
Scanning Electron

Powders of Zr, ZrO2, and ZrN were mixed and pressed to produce samples with different bulk stoichiometries in the ternary Zr–O–N systems. The samples were laser heated above melting, maintained at a high temperature, and quenched. The processed samples were cross-sectioned and studied using scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffraction. The results pointed to the location of the ternary invariant point Liquid + Gas + ZrO2 + ZrN on the high-temperature portion of the Zr–ZrO2–ZrN phase diagram. The ternary liquidus in the Zr–O–N system was further constrained based on the comparison of the results obtained in this work with composition histories of zirconium particles burning in air reported earlier. Elemental analysis of nitrogen-rich inclusions found in the samples showed the existence of an extended compositional range for ternary solid Zr–O–N solutions. X-ray diffraction analysis of the quenched samples indicated that these solutions are likely to be derived from the ZrN phase. A preliminary outline of the subsolidus ternary Zr–ZrO2–ZrN phase diagram is constructed based on these findings and the interpretations of the well-known binary Zr–O and Zr–N phase diagrams.

Structure Determination of Monoclinic RbD 2 PO 4 in the High-Temperature Phase

2002 ◽  
Vol 269 (1) ◽  
pp. 273-278 ◽  
Author(s):  
Chikako Moriyoshi ◽  
Tsutomu Fujii ◽  
Kazuyuki Itoh ◽  
Masaru Komukae
Keyword(s):  
High Temperature ◽  
Structure Determination ◽  
High Temperature Phase ◽  
Temperature Phase
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