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High-Pressure Computational Search of Trivalent Lanthanide Dinitrides

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Transition-metal nitrides have attracted much interest of the scientific community for their intriguing properties and technological applications. Here, we focus on yttrium dinitride (YN2) and its formation and structural transition under pressure. We employed a fixed composition USPEX search to find the most stable polymorphs. We choose yttrium as a proxy for the lanthanide series because it has only +3 oxidation state, contrary to most transition metals. We then computed the thermodynamic and dynamical stabilities of these structures compared to the decomposition reactions, and we found that the compound undergoes two structural transitions, the latter showing the formation of N4 chains. A closer look into the nature of the nitrogen bonding showed that in the first two structures, where nitrogen forms dimers, the bond length is intermediate between that of a single bond and that of a double bond, making it hard to rationalize the proper oxidation state configuration for YN2. In the latter structure, where there is formation of N4 chains, the bond lengths increase significantly up to a value that can be justified as a single bond. Finally, we also studied the electronic structure and dynamical stability of the structures we found.

TidsskriftJournal of Physical Chemistry C
Sider (fra-til)161-167
Antal sider7
StatusUdgivet - jan. 2021

Bibliografisk note

Funding Information:
We acknowledge the financial support from the Center for Materials Crystallgraphy (CMC). We thank Martin Bremholm and Carlo Gatti for helpful discussions. Calculations were performed at the CINECA supercomputing center, thanks to the ISCRA HP10C7BPGD, HP10C5WGQ7, and HP10CPXESJ grants.

Publisher Copyright:
© 2020 American Chemical Society.

Copyright 2021 Elsevier B.V., All rights reserved.

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