High-pressure Raman spectra of 3-methyl-4-nitropyridine N-oxide crystal and pressure-induced phase transitions

✍ Scribed by Delong Zhang; Guoxiang Lan; Shifen Hu; Huafu Wang; Jimin Zheng

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 337 KB
• Volume: 25
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/jrs.1250250507

✦ Synopsis

Abstract

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.