High-temperature and pressure Raman spectroscopy of diamond

Abstract

This study presents the results of the first use of the moissanite anvil cell (MAC) for the in-situ high-temperature and pressure Raman spectroscopy measurement of diamond. It is observed that the T 2g vibrational mode of diamond shifts toward low frequency with increasing temperature; on the other hand, the vibration band shifts toward high frequency with increasing pressure. In the high-temperature and pressure process, the slope ( ∂υ/ ∂T) becomes zero which indicates the thermal expansion. It resulted from the temperature effect, and the pressure caused by MAC will reach a balanced state about 1.6 GPa and 175 °C. The behavior of diamonds at high temperature and high pressure is mainly dominated by temperature effects for the temperature below 320 °C and the pressure less than 5 GPa.