Phase transitions of palladium under dynamic shock compression

Liu, Ze-Tao; Chen, Bin; Ling, Weidong; Bao, Nan-Yun; Kang, Dongdong; Dai, Jiayu

doi:10.7498/aps.71.20211511

Cited by 3 publications

(1 citation statement)

References 41 publications

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“…The static compression can be applied for significant long time in most material systems since a nearly isotropic strain is induced and the shear strain is negligible that is normally omitted. In contrast, the shock compression generates uniaxial strain with ultra-high rates that results in a rapid increment in temperature in candidate materials [17]. The experimental identification of phase transitions in such a drastic process is rather difficult.…”

Section: Introductionmentioning

confidence: 99%

Atomic Insight Into Phase Transition Lowering in Shock Compressed Copper

et al. 2022

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High pressure structural transformation of copper (Cu) is a rather complex physical process. One of the intriguing questions that are rarely discussed is the comparison between quasi-isentropic response and adiabatic response for copper lattice transition. The ambient face-centered-cubic structure of Cu is predicted to persist over 100 TPa from ab inito calculations and experimentally demonstrated to persist until 1.15 TPa in ramp compression and 150 GPa in static compression. However, a novel body-centered-cubic (BCC) order is observed merely at 180 GPa once shock compression is applied. The mechanism of body-centered-cubic phase transition occurred at low pressure under shock compression remains elusive so far and much attention is required on the dynamics in such a phase transition. In this work, we utilize the molecular dynamics method to simulate the shock compression on a copper lattice to uncover the structural transition in the atomic scale. We report the FCC–BCC phase transition occurred at 156 GPa, and lots of disordered structures are discovered in the BCC phase after impact, revealed by a series of structure analysis tools and free energy calculations. The plethora of transient disordered structures reduces the global Gibbs free energies, thus leading to the downgrade of the transition pressure in contrast to the ramp and static compression, which provides a new perspective for structural transformation under extreme conditions.

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Section: Introductionmentioning

confidence: 99%

Atomic Insight Into Phase Transition Lowering in Shock Compressed Copper

et al. 2022

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A database of high-pressure crystal structures from hydrogen to lanthanum

Giannessi,

Di Cataldo,

Saha

et al. 2024

Sci Data

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This paper introduces the HEX (High-pressure Elemental Xstals) database, a complete database of the ground-state crystal structures of the first 57 elements of the periodic table, from H to La, at 0, 100, 200 and 300 GPa. HEX aims to provide a unified reference for high-pressure research, by compiling all available experimental information on elements at high pressure, and complementing it with the results of accurate evolutionary crystal structure prediction runs based on Density Functional Theory. Besides offering a much-needed reference, our work also serves as a benchmark of the accuracy of current ab-initio methods for crystal structure prediction. We find that, in 98% of the cases in which experimental information is available, ab-initio crystal structure prediction yields structures which either coincide or are degenerate in enthalpy to within 300 K with experimental ones. The main manuscript contains synthetic tables and figures, while the Crystallographic Information File (cif) for all structures can be downloaded from the related figshare online repository.

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Palladium at high pressure and high temperature: A combined experimental and theoretical study

Baty,

Burakovsky,

Luscher

et al. 2024

Journal of Applied Physics

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Palladium is one of the most important technological materials, yet its phase diagram remains poorly understood. At ambient conditions, its solid phase is face-centered cubic (fcc). However, another solid phase of Pd, body-centered cubic (bcc), was very recently predicted in two independent theoretical studies to occur at high pressures and temperatures. In this work, we report an experimental study on the room-temperature equation of state (EOS) of Pd to a pressure of 80 GPa, as well as a theoretical study on the phase diagram of Pd including both fcc-Pd and bcc-Pd. Our theoretical approach consists in ab initio quantum molecular dynamics (QMD) simulations based on the Z methodology which combines both direct Z method for the simulation of melting curves and inverse Z method for the calculation of solid–solid phase transition boundaries. We obtain the melting curves of both fcc-Pd and bcc-Pd and an equation for the fcc–bcc solid–solid phase transition boundary as well as the thermal EOS of Pd which is in agreement with experimental data and QMD simulations. We uncover the presence of another solid phase of Pd on its phase diagram, namely, random hexagonal close-packed (rhcp), and estimate the location of the rhcp-bcc solid–solid phase transition boundary and the rhcp–fcc–bcc triple point. We also discuss the topological similarity of the phase diagrams of palladium and silver, the neighbor of Pd in the periodic table. We argue that Pd is a reliable standard for shock-compression studies and present the analytic model of its principal Hugoniot in a wide pressure range.

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Phase transitions of palladium under dynamic shock compression

Cited by 3 publications

References 41 publications

Atomic Insight Into Phase Transition Lowering in Shock Compressed Copper

Atomic Insight Into Phase Transition Lowering in Shock Compressed Copper

A database of high-pressure crystal structures from hydrogen to lanthanum

Palladium at high pressure and high temperature: A combined experimental and theoretical study

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