INFRARED SPECTRA AND CRYSTALLINE PHASE TRANSITIONS OF AMMONIUM NITRATE

1964 ◽  
Vol 42 (1) ◽  
pp. 57-62 ◽  
Author(s):  
A. Théorêt ◽  
C. Sandorfy
Keyword(s):  
Phase Transitions ◽  
Melting Point ◽  
Phase I ◽  
Ammonium Nitrate ◽  
Air Temperature ◽  
Infrared Spectra ◽  
Crystalline Phase ◽  
Rapid Cooling ◽  
Symmetry Properties ◽  
Crystalline Films

The infrared spectra of solid crystalline films of ammonium nitrate were measured at temperatures ranging between the melting point (169 °C) and liquid air temperature (−190 °C). Four different spectra were obtained which are shown to belong to phase I, II, IV, and (very probably) VII. Phases III and V were not encountered; only transitions [Formula: see text], [Formula: see text], and [Formula: see text] were observed. A spectrum measured at −190 °C after rapid cooling is shown to correspond to a mixture of phases IV and VII. The symmetry properties of the different phases are discussed in relation with their infrared spectra.

RAMAN AND INFRARED STUDY OF PHASE TRANSFORMATION IN CRYSTALLINE HYDROGEN IODIDE AND DEUTERIUM IODIDE HI AND DI

1989 ◽  
Vol 03 (11) ◽  
pp. 1671-1679 ◽  
Author(s):  
W.S. TSE ◽  
C.S. FANG ◽  
A. ANDERSON ◽  
B.H. TORRIE
Keyword(s):  
Phase Transformation ◽  
Phase Transitions ◽  
Melting Point ◽  
Infrared Spectra ◽  
Hydrogen Iodide ◽  
Temperature Dependent ◽  
Two Phase ◽  
Infrared Study ◽  
X Ray ◽  
Temperature Range

Raman and infrared spectra of polycrystalline HI and DI in the region of lattice and internal modes for all three phases have been recorded over the temperature range 18 K to the melting point. The temperature dependent Raman and infrared results are consistent with the X-ray and neutron work that two phase transitions occur at HI and DI involving reorientation of the HI and DI molecules as a whole.

Liquid crystalline phase transitions in hexakis(4-(4′-heptyloxy)biphenoxy)cyclotriphosphazene

1995 ◽  
Vol 18 (5) ◽  
pp. 795-800 ◽  
Author(s):  
K. Moriya ◽  
H. Mizusaki ◽  
M. Kato ◽  
S. Yano ◽  
M. Kajiwara
Keyword(s):  
Phase Transitions ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Liquid Crystalline Phase

scholarly journals Investigation of phase transitions in liquid crystal 12BBAA using window clustering of infrared spectra

2021 ◽  
Vol 341 ◽  
pp. 117233
Author(s):  
Natalia Osiecka-Drewniak ◽  
Mirosław A. Czarnecki ◽  
Zbigniew Galewski
Keyword(s):  
Phase Transitions ◽  
Liquid Crystal ◽  
Infrared Spectra

scholarly journals Thermal Expansion and Phase Transitions of Ammonium Nitrate

1967 ◽  
Vol 70 (10) ◽  
pp. 1633-1637 ◽  
Author(s):  
Masanori NAGATANI ◽  
Makoto HAYAMA ◽  
Noboru YAMAZOE ◽  
Tetsuro SEIYAMA
Keyword(s):  
Thermal Expansion ◽  
Phase Transitions ◽  
Ammonium Nitrate

Evidence for endothermic quasicrystalline–crystalline phase transitions in Al6CuMg4

Nature ◽  
1987 ◽  
Vol 328 (6132) ◽  
pp. 704-706 ◽  
Author(s):  
M. K. Sanyal ◽  
V. C. Sahni ◽  
G. K. Dey
Keyword(s):  
Phase Transitions ◽  
Crystalline Phase

scholarly journals Influence of alkyl chain length and fluorine atoms substitution on infrared spectra of chiral liquid crystalline esters

2017 ◽  
Vol 66 (3) ◽  
pp. 63-74
Author(s):  
Anna Drzewicz ◽  
Marzena Tykarska ◽  
Magdalena Żurowska
Keyword(s):  
Molecular Structure ◽  
Infrared Spectroscopy ◽  
Liquid Crystals ◽  
Infrared Spectra ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Rigid Core ◽  
Helicoidal Structure

The infrared spectra were registered for series of three-ring liquid crystalline esters, differing in the structure of alkyl chain, in the substitution of benzene ring by fluorine atoms and in the type of helicoidal structure in the chiral smectic CA phase with antiferroelectric properties. The influence of molecular structure on the shift of signals coming from carbonyl group, located in the rigid core, was observed. Keywords: liquid crystals, helicoidal structure, chiral smectic CA phase, antiferroelectric crystalline phase, infrared spectroscopy

scholarly journals Etude par resonance magnetique des mouvements moléculaires dans l'acrylonitrile solide

1973 ◽  
Vol 51 (23) ◽  
pp. 3889-3900 ◽  
Author(s):  
Buu Ban ◽  
C. CHACHATY
Keyword(s):  
Phase Transitions ◽  
Phase I ◽  
Phase Ii ◽  
Phase Iii ◽  
Solid Matrix ◽  
Peroxy Radicals ◽  
Γ Irradiation ◽  
Rotational Oscillation ◽  
Résonance Magnétique ◽  
Oxygen Addition

Phase transitions and molecular motions in solid acrylonitrile and its deuterated homologue CH2=CDCN, have been studied between 100 and 191 °K (m.p.) by wide line n.m.r. and by T1 relaxation time measurements. Phase I (164 °K < T < 191 °K) is trapped and becomes metastable by quick cooling of acrylonitrile at 77 °K. It changes into the phase II, stable between 113 °K and 164 °K by a long duration annealing at 155–160 °K. The phase II → phase III transition occurs at 113 °K. It may be assumed that phase III, stable below this temperature, is rigid at T < 105 °K. Phase II may be characterized by a rotational oscillation of molecules around an axis defined by the N atom and the middle of the vinyl double bond. In phase I, acrylonitrile molecules undergo a binary reorientation motion around this axis with an activation energy of 4.2 kcal mol−1. The motion of peroxy radicals, trapped in acrylonitrile has been also studied by e.s.r. These radicals were produced by oxygen addition to free radicals previously formed by γ irradiation of acrylonitrile at 77 °K. The g anisotropy variation with temperature, shows no discontinuities at phase transitions, the activation of reorientation of peroxy radicals being 0.65 kcal mol−1. This result suggests that we are dealing in fact with macroradicals, the internal rotation of which is only observable in a solid matrix.

scholarly journals Phase Polymorphism of [Co(DMSO)6](BF4)2 Studied by Differential Scanning Calorimetry

2006 ◽  
Vol 61 (3-4) ◽  
pp. 180-188 ◽  
Author(s):  
Anna Migdał-Mikuli ◽  
Łukasz Skoczylas ◽  
Elżbieta Szostak
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Transitions ◽  
Melting Point ◽  
Title Compound ◽  
Metastable Phases ◽  
Scanning Calorimetry ◽  
Phase Polymorphism ◽  
Solid Phases ◽  
High Degree ◽  
Dynamical Disorder

Five solid phases of [Co(DMSO)6](BF4)2 have been detected by differential scanning calorimetry (DSC). Phase transitions were detected between the following solid phases: stable KIb↔ stable KIa at T̅C4 = (328±2) K, metastable KIII ↔ undercooled phase K0 at T̅C3 = (383±4) K, metastable KII ↔ undercooled K0 at T̅C2 = (399±2) K and stable KIa ↔ stable K0 at T̅C1 = (404±1) K. The title compound melts at Tm = 440 K. From the entropy changes at the melting point and at phase transitions it can be concluded that the phases K0 and undercooled K0 are orientationally dynamically disordered crystals. The stable phases KIa, KIb are ordered solid phases. The metastable phases KII and KIII are probably solid phases with a high degree of orientational dynamical disorder

Infrared spectra of crystalline n-alkanes. Changes observed during the phase I → phase II transition

1983 ◽  
Vol 61 (8) ◽  
pp. 1736-1742 ◽  
Author(s):  
Hector L. Casal ◽  
David G. Cameron ◽  
Henry H. Mantsch
Keyword(s):  
Phase I ◽  
Phase Ii ◽  
Infrared Spectra ◽  
Rotator Phase

Detailed measurements of the changes in the infrared spectra of n-nonadceanc and n-heneicosane on transition from the orthorhombic to the so-called "hexagonal" or "rotator" phase are reported.

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