Experimental and Computational Studies on Superhard Material Rhenium Diboride under Ultrahigh Pressures

Journal Article · 03 April 2020 · Materials

DOI: https://doi.org/10.3390/ma13071657 · OSTI ID:1608873

Burrage, Kaleb C. ^[1]; Lin, Chia-Min ^[1]; Chen, Wei-Chih ^[1]; Chen, Cheng-Chien  ^[1]; Vohra, Yogesh K.  ^[1]

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1. Univ. of Alabama, Birmingham, AL (United States)

An emerging class of superhard materials for extreme environment applications are compounds formed by heavy transition metals with light elements. In this work, ultrahigh pressure experiments on transition metal rhenium diboride (ReB₂) were carried out in a diamond anvil cell under isothermal and non-hydrostatic compression. Two independent high-pressure experiments were carried out on ReB₂ for the first time up to a pressure of 241 GPa (volume compression V/V₀ = 0.731 ± 0.004), with platinum as an internal pressure standard in X-ray diffraction studies. The hexagonal phase of ReB₂ was stable under highest pressure, and the anisotropy between the a-axis and c-axis compression increases with pressure to 241 GPa. The measured equation of state (EOS) above the yield stress of ReB₂ is well represented by the bulk modulus K₀ = 364 GPa and its first pressure derivative K₀´ = 3.53. Corresponding density-functional-theory (DFT) simulations of the EOS and elastic constants agreed well with the experimental data. DFT results indicated that ReB₂ becomes more ductile with enhanced tendency towards metallic bonding under compression. The DFT results also showed strong crystal anisotropy up to the maximum pressure under study. The pressure-enhanced electron density distribution along the Re and B bond direction renders the material highly incompressible along the c-axis. Our study helps to establish the fundamental basis for anisotropic compression of ReB₂ under ultrahigh pressures

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
• Grant/Contract Number: DMR-1904164; AC02-06CH11357
• OSTI ID: 1608873
• Journal Information: Materials, Vol. 13, Issue 7; ISSN 1996-1944
• Publisher: MDPICopyright Statement
• Country of Publication: United States
• Language: ENGLISH