Description

We conducted a joint experimental–theoretical investigation of the high-pressure chemistry of europium polyhydrides at pressures of 86–130 GPa. We discovered several novel magnetic Eu superhydrides stabilized by anharmonic effects: cubic EuH9, hexagonal EuH9, and an unexpected cubic (Pm3n) clathrate phase, Eu8H46. Monte Carlo simulations indicate that cubic EuH9 has antiferromagnetic ordering with TN of up to 24 K, whereas hexagonal EuH9 and Pm3n-Eu8H46 possess ferromagnetic ordering with TC = 137 and 336 K, respectively. The electron–phonon interaction is weak in all studied europium hydrides, and their magnetic ordering excludes s-wave superconductivity, except, perhaps, for distorted pseudohexagonal EuH9. The equations of state predicted within the DFT+U approach (U – J were found within linear response theory) are in close agreement with the experimental data. This work shows the great influence of the atomic radius on symmetry-breaking distortions of the crystal structures of superhydrides and on their thermodynamic stability.

OCLC

1259521376

Document Type

Dataset

DCMI Type

Dataset

File Format

.zip, .txt, .png, .inp, .out, .pdf

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Publication Date

6-17-2021

Funder

NSF, Division of Chemistry (CHE)

Publisher

UtahState University

Award Number

NSF, Division of Chemistry (CHE) 1664379

Award Title

Deciphering Delocalized Bonding in Excited States, Solvated Species and Novel 0-, 1-, 2-, and 3-Dimensional Chemical Systems

Methodology

To investigate the formation of new chemical compounds in the Eu–H system, we purchased the europium foil with 99.99% purity from Alfa Aesar company. Two diamond anvil cells (DACs) with 100 and 150 μm culets were loaded with Eu and ammonia borane (AB), purified by sublimation, which was used as a source of hydrogen and a pressure transmitting medium (Table S1). As has been shown earlier in the synthesis of superhydrides of lanthanum,1 thorium,2 praseodymium,3 and neodymium,4 ammonia borane is an effective source of hydrogen when the metal target is heated by a short (< 0.2 s) laser pulse due to the well-known thermal decomposition reaction: NH3BH3 →H2 + poly-(BNHx)n.5,6 A tungsten plate with a thickness of 20 ± 2 μm was used as a gasket. The pressure was determined by the Raman signal of diamond.7 Heating was carried out by pulses of an infrared laser (1 μm, Nd:YAG). A part of the X-ray diffraction (XRD) patterns of all samples studied in diamond anvil cells were recorded on 4W2 beamline of the Beijing Synchrotron Research Facilities (BSRF, China) and BL15U1 synchrotron beamline at the Shanghai Synchrotron Research Facility (SSRF, China)8 using a focused (5×12 μm) monochromatic X-ray beam (20 keV, 0.6199 Å). The other part of the high-pressure XRD patterns were obtained at BL10XU in SPring-8 using monochromatic synchrotron radiation and an imaging plate detector at room temperature.9 The X-ray beam with a wavelength of 0.413 Å was focused with a polymer compound refractive lens (SU-8, produced by ANKA). The experimental X-ray diffraction images were analyzed and integrated using Dioptas software package.10 The full profile analysis of the diffraction patterns and calculations of the unit cell parameters were performed in JANA200611 using the Le Bail method.12 Additional parameters of high-pressure diamond anvil cells are listed in Table S1.

Referenced by

Semenok, D. V., Zhou, D., Kvashnin, A. G., Huang, X., Galasso, M., Kruglov, I. A., Ivanova, A. G., Gavriliuk, A. G., Chen, W., Tkachenko, N. V., Boldyrev, A. I., Troyan, I., Oganov, A. R., & Cui, T. (2021). Novel Strongly Correlated Europium Superhydrides. The Journal of Physical Chemistry Letters, 12(1), 32–40. https://doi.org/10.1021/acs.jpclett.0c03331

Language

eng

Code Lists

N/A

Comments

Total of 42 data files included, zipped into theri original directories. Chemical bonding analysis files, ELF analysis files, Supplementary Information file, Supplementary Dataset file.

Disciplines

Chemistry

License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Identifier

https://doi.org/10.26078/pkgd-4v24

Checksum

49b7110a62c27a0f2415f234c93054bd

Additional Files

README.txt (4 kB)
MD5: 95325093b9e0fa99d4625294a5a0b474

Cluster_ELF_plots.zip (2844 kB)
MD5: b24613b5617a4ba10490ab1ebd6fe8df

Solid_state_chamical_bonding.zip (10 kB)
MD5: 194ea089767047a8af837dbada0b0939

Solid_state_ELF.zip (264 kB)
MD5: f1bf09896444a65d689290653d027994

Supplementary_Information.pdf (5664 kB)
MD5: ecb875cd53c9a499269d94a7fbe74fa9

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