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Open AccessArticle

Synthesis and Ultrahigh Pressure Compression of High-Entropy Boride (Hf_0.2Mo_0.2Nb_0.2Ta_0.2Zr_0.2)B₂ to 220 GPa

by Seth Iwan, Christopher Perreault and Yogesh K. Vohra

Materials 2023, 16(1), 158; https://doi.org/10.3390/ma16010158 - 24 Dec 2022

Cited by 5 | Viewed by 3115

The high-entropy boride (Hf_0.2Mo_0.2Nb_0.2Ta_0.2Zr_0.2)B₂ material was synthesized under high-pressures and high-temperatures in a large-volume Paris-Edinburgh (PE) press from a ball-milled powder mix of HfO₂, MoO₃, Nb₂O_5, Ta₂O₅, ZrO₂, carbon black, and boron carbide. The transformation process was monitored in situ by energy-dispersive x-ray diffraction with conversion starting at 1100 °C and completed by 2000 °C with the formation of a single hexagonal AlB₂-type phase. The synthesized sample was recovered, powdered, and mixed with platinum pressure marker and studied under high pressure by angle-dispersive x-ray diffraction in a diamond anvil cell. The hexagonal AlB₂-type phase of (Hf_0.2Mo_0.2Nb_0.2Ta_0.2Zr_0.2)B₂ was found to be stable up to the highest pressure of 220 GPa reached in this study (volume compression V/V₀ = 0.70). The third order Birch-Murnaghan equation of state fit to the high-pressure data up to 220 GPa results in an ambient pressure unit cell volume

V_{0} = 28.16 \pm 0.04 Å^{3}, bulk modulus

K_{o}

= 407 ± 6 GPa, pressure derivative of bulk-modulus

K_{0}^{'}

= 2.73 ± 0.045 GPa. Our study indicates that this high-entropy boride (Hf_0.2Mo_0.2Nb_0.2Ta_0.2Zr_0.2)B₂ material is stable to ultrahigh pressures and temperatures and exhibit high bulk modulus similar to other incompressible transition metal borides like ReB₂ and Os₂B₃. Full article

(This article belongs to the Special Issue Design, Processing and Properties of High Entropy Ceramics)

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14 pages, 3788 KB

Open AccessArticle

A Paris-Edinburgh Cell for High-Pressure and High-Temperature Structure Studies on Silicate Liquids Using Monochromatic Synchrotron Radiation

by Tony Yu, Clemens Prescher, Young Jay Ryu, Feng Shi, Eran Greenberg, Vitali Prakapenka, Peter Eng, Joanne Stubbs, Yoshio Kono, Guoyin Shen, Heather Watson, Mark L. Rivers, Stephen R. Sutton and Yanbin Wang

Minerals 2019, 9(11), 715; https://doi.org/10.3390/min9110715 - 19 Nov 2019

Cited by 9 | Viewed by 7539

Abstract

A Paris-Edinburgh press combined with a multi-channel collimator assembly has been commissioned at the GeoSoilEnviro Center for Advanced Radiation Sources (GSECARS) beamline for monochromatic X-ray scattering, with an emphasis on studying low-Z liquids, especially silicate liquids at high pressure. The Paris-Edinburgh press is mounted on a general-purpose diffractometer, with a pixel array detector mounted on the detector arm. The incident monochromatic undulator beam with energies up to 60 keV is focused both horizontally and vertically to a beam size about 30 × 30 µm. With this setup, background scattering from the surrounding pressure media is completely removed at 2θ angles above 10° for samples larger than 1.05 mm in diameter. Thirty minutes is typically sufficient to collect robust X-ray scattering signals from a 1.6 mm diameter amorphous silicate sample. Cell assemblies for the standard Paris-Edinburgh anvils have been developed and pressures and temperatures up to 7 GPa and 2300 K, respectively, have been maintained steadily over hours. We have also developed a cupped-toroidal Drickamer anvil to further increase pressure and temperature capabilities. The cupped-toroidal Drickamer anvil combines features of a modified Drickamer anvil and the traditional Paris-Edinburgh anvil. Pressures up to 12 GPa have been generated at temperatures up to 2100 K. Full article

(This article belongs to the Special Issue Mineral Physics—In Memory of Orson Anderson)

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9 pages, 3651 KB

Open AccessArticle

Pressure Induced Densification and Compression in a Reprocessed Borosilicate Glass

by Kathryn J. Ham, Yoshio Kono, Parimal J. Patel, Steven M. Kilczewski and Yogesh K. Vohra

Materials 2018, 11(1), 114; https://doi.org/10.3390/ma11010114 - 12 Jan 2018

Cited by 2 | Viewed by 4347

Abstract

Pressure induced densification and compression of a reprocessed sample of borosilicate glass has been studied by X-ray radiography and energy dispersive X-ray diffraction using a Paris-Edinburgh (PE) press at a synchrotron X-ray source. The reprocessing of a commercial borosilicate glass was carried out by cyclical melting and cooling. Gold foil pressure markers were used to obtain the sample pressure by X-ray diffraction using its known equation of state, while X-ray radiography provided a direct measure of the sample volume at high pressure. The X-ray radiography method for volume measurements at high pressures was validated for a known sample of pure α-Iron to 6.3 GPa. A sample of reprocessed borosilicate glass was compressed to 11.4 GPa using the PE cell, and the flotation density of pressure recovered sample was measured to be 2.755 gm/cc, showing an increase in density of 24%, as compared to the starting sample. The initial compression of the reprocessed borosilicate glass measured by X-ray radiography resulted in a bulk modulus of 30.3 GPa in good agreement with the 32.9 GPa value derived from the known elastic constants. This method can be applied to variety of amorphous materials under high pressures. Full article

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