Raman spectra and phase diagram of fluorine at pressures up to 6 GPa and temperatures between 10 and 320 K

Abstract

The Raman spectra and phase diagram of fluorine were studied in a diamond-anvil cell up to 6 GPa over the temperature range 10–300 K. The sample slowly reacted with the diamond anvils to form CF4. The vibron frequencies in α-F2 and β-F2, as well as the lattice modes in α-F2, were determined as a function of pressure. No new phases were discovered. The α–β phase boundary can be fit with an equation of the Simon form: Pαβ (GPa)=−0.385(10) +4.80(9)×10−4 Tαβ1.75 (K). The melting curve was established to lie between limiting curves: Puppermelt (GPa)=−0.107+1.01×10−4T1.75melt (K) and Plowermelt (GPa)=−0.140+1.32×10−4 T1.75melt (K).