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Büscher J, Mirone A, Stękiel M, Spahr D, Morgenroth W, Haussühl E, Milman V, Bosak A, Ivashko O, von Zimmermann M, Dippel AC, Winkler B. Elastic stiffness coefficients of thiourea from thermal diffuse scattering. J Appl Crystallogr 2021; 54:287-294. [PMID: 33833654 PMCID: PMC7941310 DOI: 10.1107/s1600576720016039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 12/09/2020] [Indexed: 11/17/2022] Open
Abstract
The elastic stiffness coefficients of thiourea are determined from thermal diffuse scattering. The complete elastic stiffness tensor of thiourea has been determined from thermal diffuse scattering (TDS) using high-energy photons (100 keV). Comparison with earlier data confirms a very good agreement of the tensor coefficients. In contrast with established methods to obtain elastic stiffness coefficients (e.g. Brillouin spectroscopy, inelastic X-ray or neutron scattering, ultrasound spectroscopy), their determination from TDS is faster, does not require large samples or intricate sample preparation, and is applicable to opaque crystals. Using high-energy photons extends the applicability of the TDS-based approach to organic compounds which would suffer from radiation damage at lower photon energies.
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Affiliation(s)
- Julia Büscher
- Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt am Main, Germany
| | - Alessandro Mirone
- European Synchrotron Radiation Facility, 71 avenue des Martyrs, Grenoble, France
| | - Michał Stękiel
- Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt am Main, Germany
| | - Dominik Spahr
- Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt am Main, Germany
| | - Wolfgang Morgenroth
- Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt am Main, Germany
| | - Eiken Haussühl
- Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt am Main, Germany
| | | | - Alexei Bosak
- European Synchrotron Radiation Facility, 71 avenue des Martyrs, Grenoble, France
| | - Oleh Ivashko
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, Hamburg, Germany
| | | | | | - Björn Winkler
- Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt am Main, Germany
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Laniel D, Winkler B, Fedotenko T, Pakhomova A, Chariton S, Milman V, Prakapenka V, Dubrovinsky L, Dubrovinskaia N. High-Pressure Polymeric Nitrogen Allotrope with the Black Phosphorus Structure. PHYSICAL REVIEW LETTERS 2020; 124:216001. [PMID: 32530671 DOI: 10.1103/physrevlett.124.216001] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
Studies of polynitrogen phases are of great interest for fundamental science and for the design of novel high energy density materials. Laser heating of pure nitrogen at 140 GPa in a diamond anvil cell led to the synthesis of a polymeric nitrogen allotrope with the black phosphorus structure, bp-N. The structure was identified in situ using synchrotron single-crystal x-ray diffraction and further studied by Raman spectroscopy and density functional theory calculations. The discovery of bp-N brings nitrogen in line with heavier pnictogen elements, resolves incongruities regarding polymeric nitrogen phases and provides insights into polynitrogen arrangements at extreme densities.
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Affiliation(s)
- Dominique Laniel
- Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany
| | - Bjoern Winkler
- Institut für Geowissenschaften, Abteilung Kristallographie, Johann Wolfgang Goethe-Universität Frankfurt, Altenhöferallee 1, D-60438 Frankfurt am Main, Germany
| | - Timofey Fedotenko
- Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany
| | - Anna Pakhomova
- Photon Science, Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
| | - Stella Chariton
- Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, USA
| | - Victor Milman
- Dassault Systèmes BIOVIA, CB4 0WN Cambridge, United Kingdom
| | - Vitali Prakapenka
- Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, USA
| | - Leonid Dubrovinsky
- Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany
| | - Natalia Dubrovinskaia
- Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany
- Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
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Abstract
The Raman spectra of barite and celestine were recorded from 25 to 600 °C at ambient pressure and both minerals were stable over the entire temperature range. Most of the Raman bands of barite decreased in wavenumber with increasing temperature with the exception of the ν2 modes and the ν4 band at 616 cm−1, which did not exhibit a significant temperature dependence. These vibrations may be constrained by the lower thermal expansion along the a-axis and b-axis of barite. Similar to barite, most of the Raman bands of celestine also decreased in wavenumber with increasing temperature, with the exception of the ν2 modes and the ν4 band at 622 cm−1, which showed very little variation with increasing temperature. Variations of Raman shift as a function of temperature and FWHM (full width at half maximum) as a function of Raman shift for the main, ν1 modes of barite and celestine show that both minerals have almost identical linear trends with a slope of −0.02 cm−1/°C and −0.5, respectively, which allows for the prediction of Raman shifts and FWHM up to much higher temperatures. The calculated isobaric and isothermal mode Grüneisen parameters and the anharmonicity parameters show that the M–O modes (M = Ba2+ and Sr2+) in barite and celestine exhibit much higher values of both mode Grüneisen parameters and anharmonicity than the SO4 tetrahedra. This indicates that the S–O distances and S–O–S angles are less sensitive to pressure and temperature increase than the M–O distances in the structure. Furthermore, the generally higher anharmonicity in celestine is due to the smaller size of the Sr2+ cation, which causes the celestine structure to be more distorted than the barite structure.
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