Ferroelastic phase transition in cryolite, Na3AlF6, a mixed fluoride perovskite: High temperature single crystal X-ray diffraction study and symmetry analysis of the transition mechanism

1993 ◽  
Vol 19 (8) ◽  
Author(s):  
Hexiong Yang ◽  
Subrata Ghose ◽  
DorianM. Hatch
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Single Crystal ◽  
Diffraction Study ◽  
Symmetry Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transition Mechanism ◽  
Ferroelastic Phase Transition

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.

Low- and high-temperature structures of YbCuBi

2006 ◽  
Vol 221 (5-7) ◽  
Author(s):  
Andriy V. Tkachuk ◽  
Yurij Mozharivskyj ◽  
Arthur Mar
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Intermetallic Compound ◽  
Single Crystal ◽  
Diffraction Study ◽  
Low Temperatures ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
X Ray

AbstractA variable temperature single-crystal X-ray diffraction study was undertaken on the intermetallic compound YbCuBi, which undergoes a phase transition at ∼375 K. At low temperatures (

A new high-pressure phase transition in clinoferrosilite: In situ single-crystal X-ray diffraction study

2017 ◽  
Vol 102 (3) ◽  
pp. 666-673 ◽  
Author(s):  
Anna Pakhomova ◽  
Leyla Ismailova ◽  
Elena Bykova ◽  
Maxim Bykov ◽  
Tiziana Boffa Ballaran ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Single Crystal ◽  
Diffraction Study ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure Phase Transition ◽  
Pressure Phase

High-pressure single-crystal X-ray diffraction study of katoite hydrogarnet: Evidence for a phase transition fromIa3d→I4̅3dsymmetry at 5 GPa

2002 ◽  
Vol 87 (5-6) ◽  
pp. 642-647 ◽  
Author(s):  
George A. Lager ◽  
Robert T. Downs ◽  
Marcus Origlieri ◽  
Rebecca Garoutte
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Single Crystal ◽  
Diffraction Study ◽  
X Ray Diffraction ◽  
X Ray
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