Structure Study of Supercritical CO2near Higher-Order Phase Transition Line by X-ray Diffraction

1997 ◽  
Vol 101 (36) ◽  
pp. 7158-7162 ◽  
Author(s):  
Takeshi Morita ◽  
Keiko Nishikawa ◽  
Masakazu Takematsu ◽  
Hanae Iida ◽  
Seiya Furutaka
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
Structure Study ◽  
Higher Order ◽  
Transition Line ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Transition Line

Study of phase transition line of PZT ceramics by X-ray diffraction

1995 ◽  
Vol 21 (6) ◽  
pp. 391-394 ◽  
Author(s):  
A. Boutarfaia ◽  
C. Boudaren ◽  
A. Mousser ◽  
S.E. Bouaoud
Keyword(s):  
Phase Transition ◽  
Transition Line ◽  
X Ray Diffraction ◽  
Pzt Ceramics ◽  
X Ray ◽  
Phase Transition Line

High-Pressure Studies of the Rotor-Stator Compound C60-Cubane

2006 ◽  
Vol 987 ◽  
Author(s):  
Bertil Sundqvist ◽  
Agnieszka Iwasiewicz-Wabnig ◽  
Eva Kovats ◽  
Sandor Pekker
Keyword(s):  
Phase Transition ◽  
Atmospheric Pressure ◽  
Orthorhombic Phase ◽  
Transition Line ◽  
X Ray Diffraction ◽  
X Ray ◽  
Treatment Conditions ◽  
High Pressure Studies ◽  
Different Temperatures ◽  
Polymeric State

AbstractInsertion of cubane (C8H8) into the octahedral voids of the C60 lattice leads to the formation of an interesting rotor-stator compound which can be converted into a C60 co-polymer by heating. We have treated a number of C60·C8H8 samples for up to 3 h each in the range 380-875 K under pressures up to 2 GPa. The resulting materials were investigated by Raman spectroscopy and X-ray diffraction. Depending on treatment conditions, at least five different structural phases can be found. In addition to the four structural phases observed at atmospheric pressure and different temperatures we find that a new polymeric state is created at pressures above 1 GPa, and we tentatively identify its structure as pseudo-orthorhombic. The cubic-orthorhombic phase transition line is found to have a slope of 295 K GPa-1, much larger than the slope of the fcc-sc line in pure C60.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

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