Relative stability and elastic properties of hcp, bcc, and fcc beryllium under pressure

High-pressure–temperature phase diagram and the equation of state of beryllium

“…At high pressure, the stability domain of the bcc phase has not been reached, which contradicts some theoretical predictions 4,5 . The experimental cold compression curve of the hcp α-Be up to 191 GPa reveals a slight overestimation of bulk modulus under high pressure by the generalized gradient approximation [5][6][7]13 . P -V -T data of hcp beryllium have been obtained in the 20-82 GPa and 300-2600K P -T range.…”

“…Instead, a bcc phase is predicted to appear close to the melting line above 100 GPa 5,6,13,14 . Recent experimental studies have seen no evidence for the bcc phase, either at low pressure, or up to 200 GPa at ambient temperature 15,16 , or between 15 and 50 GPa at temperatures up to 2000K…”

Research on the Lattice Stability of Elemental Be, Mg, Ca, Sr, Ba and Ra by the Ultra-Soft Pseudo-Potential Method in First Principles

“…For hcp-Be, the listed five data from first-principles calculations include that of the Hartree-Fock self-consistent-field linear-combination-of-atomic-orbitals (HF-SCF-LCAO) method, [27] the full-potential-linear-muffin-tin-orbital (FPLMTO) method, [28] the local-densityapproximation(LDA) method, [29] the Perdew-Wang parameterization of generalized gradient approximation with projector augmented-wave method (PW91-GGA-PAW) [30] and the Perdew-Burke-Ernzerhof parameterization of generalized gradient approximation with ultra-soft pseudo-potential method (PBE-GGA-USPP) in this work. The total energy functional for USPP can be obtained by linearization of two terms in a slightly modified PAW total energy functional, furthermore, the USPP method can offer in general a similar precision like PAW method due to such close relationship except the magnetic systems.…”

Megaamps, megagauss, and megabars: Using the Sandia Z Machine to perform extreme material dynamics experiments

“…The widely accepted phase diagram for beryllium at the onset of this work was described by Sin'ko and Smirnov [14]. At ambient pressure and high temperature, just below melt, beryllium has been reported to undergo an hcp to bcc transition.…”

“…Also, theoretical calculations suggested an hcp to bcc transition at zero K and high pressure. Thus it was assumed that these transition points were connected by a single phase boundary, at that the Hugoniot of beryllium would cross this phase boundary before encountering melt [14].…”