Journal article
Electronic origins of the giant volume collapse in the pyrite mineral MnS2
University of Nevada, Las Vegas1
Oak Ridge National Laboratory2
European Synchrotron Radiation Facility3
University of Bayreuth4
Lawrence Livermore National Laboratory5
Department of Physics, Technical University of Denmark6
Technical University of Denmark7
Neutrons and X-rays for Materials Physics, Department of Physics, Technical University of Denmark8
Institut Laue-Langevin9
Ehime University10
...and 0 moreThe pyrite mineral MnS2 was recently shown to undergo a giant pressure-induced volume collapse at ∼ 12 GPa, via a disordered intermediate phase. The high pressure arsenopyrite phase is stabilised by metal-metal bonding, a mechanism now shown to be ubiquitous for Mn2+ chalcogenides. Here we report a spectroscopic investigation of this transition up to pressures of 22 GPa.
Using XANES we show that the transition does not involve a change in oxidation state, consistent with the arsenopyrite crystal structure proposed at high pressure. Notably, the XANES spectrum is almost identical in the pressure-induced disordered phase, and after crystallisation induced by laser-heating.
The former is therefore a ‘valence bond glass’, and is likely disordered due to kinetic hindrance of the phase transition. We also detect electronic changes in the compressed pyrite phase, and this is confirmed by Raman scattering which shows that the disulphide vibrations in the pyrite phase saturate before the volume collapse.
Together with detailed DFT calculations, these results indicate that electronic changes precede valence bond formation between the Mn2+ cations.
Language: | English |
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Year: | 2019 |
Pages: | 540-546 |
ISSN: | 1095726x and 00224596 |
Types: | Journal article |
DOI: | 10.1016/j.jssc.2018.10.032 |
ORCIDs: | Kantor, Innokenty |