Raman and X-Ray Scattering Studies of High-Pressure Phases of Urea

Fj, Lamelas; Za, Dreger; Ym, Gupta

doi:10.1021/jp040760m

Cited by 40 publications

(73 citation statements)

References 26 publications

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“…The morphology of parent and product phase areas can be also studied in situ in real time with comparable spatial and temporal resolution by optical methods including Raman spectroscopy. 15,[22][23][24][25] However, these methods cannot provide structural information directly because it can be obtained only based on known structure/optical property relations. These relationships are not readily obtained during phase transitions accompanied by a drastic change in the type of chemical bonding.…”

Section: Morphology Of Phasesmentioning

confidence: 99%

High pressure Laue diffraction and its application to study microstructural changes during the α → β phase transition in Si

Popov

Park

Kenney‐Benson

et al. 2015

Review of Scientific Instruments

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An approach using polychromatic x-ray Laue diffraction is described for studying pressure induced microstructural changes of materials under pressure. The advantages of this approach with respect to application of monochromatic x-ray diffraction and other techniques are discussed. Experiments to demonstrate the applications of the method have been performed on the α → β phase transition in Si at high pressures using a diamond anvil cell. We present the characterization of microstructures across the α-β phase transition, such as morphology of both the parent and product phases, relative orientation of single-crystals, and deviatoric strains. Subtle inhomogeneous strain of the single-crystal sample caused by lattice rotations becomes detectable with the approach.

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Section: Morphology Of Phasesmentioning

confidence: 99%

High pressure Laue diffraction and its application to study microstructural changes during the α → β phase transition in Si

Popov

Park

Kenney‐Benson

et al. 2015

Review of Scientific Instruments

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“…[13][14][15][16][17] As we expected, changes in the hydrogen bonding interactions play a critical role in structural conformation in these systems. Nevertheless, there have been limited reports on structural changes of hydrogen-bonded supramolecular materials under high pressure.…”

Section: Introductionmentioning

confidence: 99%

Pressure-Induced Phase Transition in Hydrogen-Bonded Supramolecular Adduct Formed by Cyanuric Acid and Melamine

et al. 2009

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Single-crystal samples of the 1:1 adduct between cyanuric acid and melamine (CA.M), an outstanding case of noncovalent synthesis, have been studied by Raman spectroscopy and synchrotron X-ray diffraction in a diamond anvil cell up to pressures of 15 GPa. The abrupt changes in Raman spectra around 4.4 GPa have provided convincing evidence for pressure-induced structural phase transition. This phase transition was confirmed by angle dispersive X-ray diffraction (ADXRD) experiments to be a space group change from C2/m to its subgroup P2(1)/m. On release of pressure, the observed transition was irreversible, and the new high-pressure phase was fully preserved at ambient conditions. We propose that this phase transition was due to supramolecular rearrangements brought about by changes in the hydrogen bonding networks.

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“…In recent years, phenomena such as structural phase transition, negative compression, chemical reactions, and piezochromic luminescence have been found and reported . Meanwhile, scientists also found the structure of supramolecular materials based on the urea model can be significantly changed in high‐pressure conditions because their intermolecular interactions can be altered by compression . Referring to our previous researches, due to the obvious anisotropy of the intermolecular noncovalent interactions, weak low‐dimensional hydrogen bonds are more likely to be changed dramatically under high pressure …”

Section: Introductionmentioning

confidence: 82%

High‐pressure‐induced phase transition in 1,3‐diphenylurea: The approaching of N–H⋯O hydrogen‐bonded chains

Dai

2019

J Raman Spectroscopy

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The crystal structure and hydrogen‐bonded chains of 1,3‐diphenylurea were found to have abrupt changes when the pressure increased to 1.8 GPa. Based on Raman spectra, the intermolecular interactions, the vibrations of chemical groups, and the molecular conformation were clearly distinguished from the initial state. The anisotropic compression of the original crystal structure and the occurrence of structural phase transition were confirmed by the results of in situ high‐pressure synchrotron X‐ray diffraction experiments. The new phase was stable up to about 10.0 GPa. The inevitable creasing of the N–H⋯O hydrogen‐bonded chains was derived from the remarkable shrink of distance between hydrogen‐bonded chains, which can be treated as the main reason leading to this phase transition. The first‐principle calculations and Hirshfeld surfaces further confirmed the analysis of the experimental results. This study demonstrates that excessively reducing the space between of hydrogen‐bonded chains will rearrange the self‐assembly of supramolecular materials.

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Raman and X-Ray Scattering Studies of High-Pressure Phases of Urea

Cited by 40 publications

References 26 publications

High pressure Laue diffraction and its application to study microstructural changes during the α → β phase transition in Si

High pressure Laue diffraction and its application to study microstructural changes during the α → β phase transition in Si

Pressure-Induced Phase Transition in Hydrogen-Bonded Supramolecular Adduct Formed by Cyanuric Acid and Melamine

High‐pressure‐induced phase transition in 1,3‐diphenylurea: The approaching of N–H⋯O hydrogen‐bonded chains

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