Graphite under pressure: Equation of state and first-order Raman modes

✍ Scribed by Hanfland, M.; Beister, H.; Syassen, K.

• Book ID: 111913101
• Publisher: The American Physical Society
• Year: 1989
• Tongue: English
• Weight: 337 KB
• Volume: 39
• Category: Article
• ISSN: 1098-0121
• DOI: 10.1103/physrevb.39.12598

✦ Synopsis

We have measured lattice parameters and Raman spectra of hexagonal graphite at pressures up to the structural phase transition near 14 CiPa (T =300 K). The frequencies of the E2g(1) rigid-layer shear mode at 44 cm ' and the E2g(2) in-plane mode at 1579 cm ' increase sublinearly under pressure with initial pressure coefficients of 4.8(5) and 4.7(3) crn /GPa, respectively. Using the a-and c-axis compression data, we determine the dependence of phonon frequencies on intralayer and in- terlayer separation. For the high-frequency E2g(2) mode we find d ln co/3 din a = 1.06(10), which is in the range of bond-length scaling parameters of phonon frequencies in three-dimensional covalent structures. For the low-frequency E2g(1) mode we obtain d ln co/3d ln c =1. 4(1), which indicates a stronger anharmonicity of this mode.