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High‐pressure Raman spectra of 3‐methyl‐4‐nitropyridine N ‐oxide crystal and pressure‐induced phase transitions
Author(s) -
Zhang Delong,
Lan Guoxiang,
Hu Shifen,
Wang Huafu,
Zheng Jimin
Publication year - 1994
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250250507
Subject(s) - raman spectroscopy , amorphous solid , phase transition , crystal (programming language) , diamond anvil cell , phase (matter) , chemistry , spectral line , analytical chemistry (journal) , oxide , crystal structure , ambient pressure , crystallography , polymerization , materials science , high pressure , condensed matter physics , thermodynamics , polymer , organic chemistry , optics , programming language , physics , astronomy , computer science
Raman spectra of a 3‐methyl‐4‐nitropyridine N ‐oxide crystal were investigated as a function of pressure in a diamond‐anvil cell up to 93 kbar at room temperature. The crystal shows successive reversible phase transitions at 8, 20 and 60 kbar. Above 60 kbar, all of the external Raman peaks and most of the internal peaks were found to vanish, and this is interpreted as due to polymerization or a crystalline‐to‐amorphous phase transition. On decreasing the pressure, this amorphous state persists to about 20 kbar, and then the spectrum can be recovered completely on decreasing the pressure continuously to ambient, Zallen and Slade's vibrational scaling law was successfully checked.