High pressure equation of state studies using methanol–ethanol–water and argon as pressure media

We have measured the equation of state of the intermetallic compound AuIn2 up to 20 GPa and Cd0.8Hg0.2 up to 50 GPa using methanol–ethanol–water solution or argon as pressure media. In the experiments performed with argon as pressure medium, we minimized non-hydrostatic conditions by thermally annealing the sample. We present data revealing compressibility anomalies in AuIn2 at 2.7 GPa and in Cd0.8Hg0.2 near 8, 18 and 34 GPa with methanol–ethanol–water and argon. At pressures above 5 GPa the P–V data for AuIn2 and Cd0.8Hg0.2 from experiments preformed with argon as a pressure medium start deviating from those using methanol–ethanol–water, and the equation of state based on experiments in argon is stiffer compared with that in methanol–ethanol–water. This behavior is consistent with the relative merits of the two pressure transmitting media as documented in the literature. We also provide a brief summary of the results of electronic structure calculations that associate these anomalies with electronic topological transitions.