Stability and equation of state of face-centered cubic and hexagonal close packed phases of argon under pressure

Abstract The compression of argon is measured between 10 K and 296 up to 20 GPa 114 at in diamond anvil cells. Three samples conditioning are used: (1) single crystal sample directly compressed the anvils, (2) powder (3) a pressure medium. A partial transformation face-centered cubic (fcc) phase hexagonal close-packed (hcp) structure observed above 4.2–13 GPa. Hcp forms through stacking faults fcc-Ar its amount depends on pressurizing conditions starting microstructure. quasi-hydrostatic equation state fcc well described by quasi-harmonic Mie–Grüneisen–Debye formalism, with following 0 parameters for Rydberg-Vinet equation: $$V_0$$ V 0 = 38.0 Å $$^3$$ 3 /at, $$K_0$$ K 2.65 GPa, $$K'_0$$ ? 7.423. Under current experimental conditions, non-hydrostaticity affects P – V points mostly moderate ( $$\le$$ ? GPa).