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arXiv · 2105.11288

High-Pressure Na3(N2)4, Ca3(N2)4, Sr3(N2)4, and Ba(N2)3 Featuring Nitrogen Dimers with Non-Integer Charges and Anion-Driven Metallicity

Dominique Laniel·Bjoern Winkler·Timofey Fedotenko·Alena Aslandukova·Andrey Aslandukov·Sebastian Vogel·Thomas Meier·Maxim Bykov·Stella Chariton·Konstantin Glazyrin·Victor Milman·Vitali Prakapenka·Wolfgang Schnick·Leonid Dubrovinsky·Natalia Dubrovinskaia
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Abstract

Charged nitrogen dimers are ubiquitous in high-pressure binary metal-nitrogen systems. They are known to possess integer formal charges x varying from one through four. Here, we present the investigation of the binary alkali- and alkaline earth metal-nitrogen systems, Na-N, Ca-N, Sr-N, Ba-N to 70 GPa. We report on compounds-Na3(N2)4, Ca3(N2)4, Sr3(N2)4, and Ba(N2)3-featuring charged nitrogen dimers with paradigm-breaking non-integer charges, x = 0.67, 0.75 and 1.5. The metallic nature of all four compounds is deduced from ab initio calculations. The conduction electrons occupy the pi* antibonding orbitals of the charged nitrogen dimers that results in anion-driven metallicity. Delocalization of these electrons over the pi* antibonding states enables the non-integer electron count of the dinitrogen species. Anion-driven metallicity is expected to be found among a variety of compounds with homoatomic anions (e.g., polynitrides, carbides, and oxides), with the conduction electrons playing a decisive role in their properties.

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Dominique Laniel, Bjoern Winkler, Timofey Fedotenko, Alena Aslandukova, Andrey Aslandukov, Sebastian Vogel, Thomas Meier, Maxim Bykov, Stella Chariton, Konstantin Glazyrin, Victor Milman, Vitali Prakapenka, Wolfgang Schnick, Leonid Dubrovinsky, Natalia Dubrovinskaia. 2021-05-24. High-Pressure Na3(N2)4, Ca3(N2)4, Sr3(N2)4, and Ba(N2)3 Featuring Nitrogen Dimers with Non-Integer Charges and Anion-Driven Metallicity. https://arxiv.org/abs/2105.11288

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