The phase transition of nicotinic acid under high pressure

By using Raman spectroscopic and diamond anvil cell (DAC) technique, the high-pressure Raman spectra of nicotinic acid have been conducted up to 17 GPa. According to the experimental results, nicotinic acid has undergone a possible structural phase transition at 2.5 GPa. At pressures higher than 17 GPa, all the Raman bands disappeared, suggesting a pressure-induced amorphization happens. After the pressure released to ambient condition, the Raman spectrum maintains the profile of that at 17 GPa, indicating that the amorphous state of nicotinic acid could be quenched to ambient.