Equation of state and phase diagram of solid <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi mathvariant="normal">He</mi></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>4</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow></math> from single-crystal x-ray diffraction over a large P-T domain

P. Loubeyre; R. LeToullec; J. P. Pinceaux; H. K. Mao; J. Hu; R. J. Hemley

doi:10.1103/PhysRevLett.71.2272

Equation of state and phase diagram of solid ${}^{4}{He}$ from single-crystal x-ray diffraction over a large P-T domain

P. Loubeyre, R. LeToullec, J. P. Pinceaux, H. K. Mao, J. Hu, and R. J. Hemley

Phys. Rev. Lett. 71, 2272 – Published 4 October 1993

Abstract

Single-crystal x-ray diffraction has been performed on solid ${}^{4}{He}$ from 1 to 58 GPa over the temperature range 46–400 K. The high-density properties of helium are pinned down: the hcp structure is stable apart from an fcc loop along melting in between 15 K and around 285 K; comparison of the 304 K hcp equation of state with a series of calculations demonstrates there are significant attractive many-body interactions; and the thermal pressure has been measured between 95 and 304 K and it differs from self-consistent phonon calculations.