title: Pressure-induced phase transition in N-H···O hydrogen-bonded molecular crystal oxamide.
abstract: The effect of high pressure on the structural stability of oxamide has been investigated in a diamond anvil cell by Raman spectroscopy up to ∼14.6 GPa and by angle-dispersive X-ray diffraction (ADXRD) up to ∼17.5 GPa. The discontinuity in Raman shifts around 9.6 GPa indicates a pressure-induced structural phase transition. This phase transition is confirmed by the change of ADXRD spectra with the symmetry transformation from P1 to P1. On total release of pressure, the diffraction pattern returns to its initial state, implying this transition is reversible. We discuss the pressure-induced variations in N-H stretching vibrations and the amide modes in Raman spectra and propose that this phase transition is attributed to the distortions of the hydrogen-bonded networks.
authors: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China.
authors: Tingting
authors: T
authors: Yan
authors: Shourui
authors: S
authors: Li
authors: Kai
authors: K
authors: Wang
authors: Xiao
authors: X
authors: Tan
authors: Zhangmei
authors: Z
authors: Jiang
authors: Ke
authors: K
authors: Yang
authors: Bingbing
authors: B
authors: Liu
authors: Guangtian
authors: G
authors: Zou
authors: Bo
authors: B
authors: Zou