Phase transitions and chemical transformations of benzene up to 550 °C and 30 GPa

The phase diagram of benzene has been investigated up to 550 °C and 30 GPa in a diamond anvil cell by Raman scattering. A new triple point at 400 °C and 5 GPa and a new phase of solid benzene, called phase IV, have been located at high temperature. The boundaries have been determined between the following solid phases: (i) benzene II and benzene III; (ii) benzene III and benzene III′. The irreversible chemical transformation line of benzene has been determined and can be divided in three parts leading to three different recovered compounds. The P–T diagram obtained by our experimental results is discussed in comparison with published works.