Structural and energetic analyses of the α to β phase transition in poly(butylene terephthalate)

1989 ◽  
Vol 22 (3) ◽  
pp. 1267-1272 ◽  
Author(s):  
Robert P. Grasso ◽  
Brian C. Perry ◽  
Jack L. Koenig ◽  
Jerome B. Lando
Keyword(s):  
Phase Transition ◽  
Butylene Terephthalate ◽  
Β Phase

Spectroscopic Characterization of the α⇌β Crystalline Phase Transition in Poly(Butylene Terephthalate) and its Copolymers with Poly(Tetramethylene Oxide).

1986 ◽  
Vol 79 ◽  
Author(s):  
Eva Dobrovolny-Marand ◽  
Shaw Ling Hsu
Keyword(s):  
Phase Transition ◽  
Volume Ratio ◽  
Spectroscopic Characterization ◽  
Intramolecular Interactions ◽  
Butylene Terephthalate ◽  
Β Phase ◽  
The Mean ◽  
Hard Segments ◽  
Tetramethylene Oxide

AbstractThe stress-induced crystalline α⇌β phase transition found in poly(butylene terephthalate) and its copolymers with poly(tetramethylene oxide) has been studied by Fourier transform infrared spectroscopy coupled with mechanical measurements. The phase transformation behavior was explained in terms of a cooperative model which considered both intermolecular as well as intramolecular interactions within the crystal. It was shown that the strength of the intramolecular interactions increased with length of the hard segments and that the strength of the intermolecular interactions increased with perfection and lateral size of the crystals. The intermolecular interaction was assumed to be dominated by the interaction between neighboring terephthalate groups. The “mean” intramolecular energy was estimated at 0.40 Kcal/mole. This calculation was based on the potential energy of rotations of a carbonyl group about a benzene-carbonyl bond. Cooperativity between chains diminished when the surface to volume ratio increased above 2 x 10-2 Å-1.

Heat Capacity in α-β Phase Transition of Quartz

1985 ◽  
Vol 54 (2) ◽  
pp. 625-629 ◽  
Author(s):  
Masahide Matsuura ◽  
Haruhiko Yao ◽  
Kazutoshi Gouhara ◽  
Ichiro Hatta ◽  
Norio Kato
Keyword(s):  
Phase Transition ◽  
Heat Capacity ◽  
Β Phase

Site-occupation tendencies for ternary additions (Fe, Co, Ni) in β-phase transition-metal aluminides

1995 ◽  
Vol 51 (13) ◽  
pp. 8102-8106 ◽  
Author(s):  
Mahalingam Balasubramanian ◽  
Douglas M. Pease ◽  
Joseph I. Budnick ◽  
Tariq Manzur ◽  
Dale L. Brewe
Keyword(s):  
Phase Transition ◽  
Transition Metal ◽  
Site Occupation ◽  
Β Phase ◽  
Ternary Additions ◽  
Metal Aluminides

Topotactic, pressure-driven, diffusion-less phase transition of layered CsCoO2 to a stuffed cristobalite-type configuration

2019 ◽  
Vol 75 (4) ◽  
pp. 704-710
Author(s):  
Naveed Zafar Ali ◽  
Branton J. Campbell ◽  
Martin Jansen
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Three Dimensional ◽  
Phase Cell ◽  
Ambient Conditions ◽  
Space Group ◽  
Layered Architecture ◽  
Β Phase ◽  
Vertex Sharing ◽  
Two Phases

CsCoO2, featuring a two-dimensional layered architecture of edge- and vertex-linked CoO4 tetrahedra, is subjected to a temperature-driven reversible second-order phase transformation (α → β) at 100 K, which corresponds to a structural relaxation with concurrent tilting and breathing modes of edge-sharing CoO4 tetrahedra. In the present investigation, it was found that pressure induces a phase transition, which encompasses a dramatic change in the connectivity of the tetrahedra. At 923 K and 2 GPa, β-CsCoO2 undergoes a first-order phase transition to a new quenchable high-pressure polymorph, γ-CsCoO2. It is built up of a three-dimensional cristobalite-type network of vertex-sharing CoO4 tetrahedra. According to a Rietveld refinement of high-resolution powder diffraction data, the new high-pressure polymorph γ-CsCoO2 crystallizes in the tetragonal space group I41/amd:2 (Z = 4) with the lattice constants a = 5.8711 (1) and c = 8.3214 (2) Å, corresponding to a shrinkage in volume by 5.7% compared with the ambient-temperature and atmospheric pressure β-CsCoO2 polymorph. The pressure-induced transition (β → γ) is reversible; γ-CsCoO2 stays metastable under ambient conditions, but transforms back to the β-CsCoO2 structure upon heating to 573 K. The transformation pathway revealed is remarkable in that it is topotactic, as is demonstrated through a clean displacive transformation track between the two phases that employs the symmetry of their common subgroup Pb21 a (alternative setting of space group No. 29 that matches the conventional β-phase cell).

Crystal structure, phase transition and properties of indium(iii) sulfide

2020 ◽  
Vol 49 (44) ◽  
pp. 15903-15913
Author(s):  
Paweł Wyżga ◽  
Wilder Carrillo-Cabrera ◽  
Lev Akselrud ◽  
Igor Veremchuk ◽  
Jörg Wagler ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Dft Calculations ◽  
Crystal Structures ◽  
Thermoelectric Properties ◽  
Structural Part ◽  
Β Phase ◽  
Structure Phase ◽  
Structure Phase Transition

This report presents studies of crystal structures of α- and β-In2S3 as well as a mechanism of the 1st order α–β phase transition. The structural part is supported by an analysis of thermoelectric properties and by DFT calculations.

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