Static compression of rare earth metal holmium to 282 GPa

ABSTRACT

The phase transitions and equation of state measurements were carried out on rare earth metal Holmium (Ho) to 282 GPa using toroidal diamond anvils thereby doubling the pressure range to which it has been studied previously. The first set of experiment employed standard beveled diamond anvils utilizing copper as an x-ray pressure standard to 217 GPa. The second set of experiment employed toroidal diamond anvils utilizing platinum as an x-ray pressure standard to 282 GPa. The recently proposed 16-atom orthorhombic structure (oF16) appeared to be stable between 103 and 282 GPa. The scaled axial ratio (c/a) shows a narrow range of variation of 1.58 ± 0.05 for the five known crystalline phases of Ho to 282 GPa. The experimental equation of state of Ho is presented up to a threefold volume compression V/V_o = 0.322.

KEYWORDS:

• Rare earth metals
• ultrahigh pressures
• equation of state

Acknowledgements

We thank Kaleb Burrage for his help in FIB machining of the toroidal diamond anvils utilized in experiments.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This material is based upon work supported by the Department of Energy-National Nuclear Security Administration under Award Number DE-NA0003916. Portions of this work were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operations are supported by DOE-NNSA’s Office of Experimental Sciences. The Advanced Photon Source is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.