High-Pressure Yttrium Nitride, Y<sub>5</sub>N<sub>14</sub>, Featuring Three Distinct Types of Nitrogen Dimers
Andrey Aslandukov, Alena Aslandukovа, Dominique Laniel, Iuliia Koemets, Timofey Fedotenko, Liang Yuan, Gerd Steinle‐Neumann, Konstantin Glazyrin, Michael Hanfland, Leonid Dubrovinsky, Natalia Dubrovinskaia
Abstract
Yttrium nitride, Y5N14, was synthesized by direct reaction between yttrium and nitrogen at ∼50 GPa and ∼2000 K in a laser-heated diamond anvil cell. High-pressure single-crystal X-ray diffraction revealed that the crystal structure of Y5N14 (space group P4/mbm) contains three distinct types of nitrogen dimers. Crystal chemical analysis and ab initio calculations demonstrated that the dimers [N2]x− are crystallographically and chemically nonequivalent and possess distinct noninteger formal charges (x) that make Y5N14 unique among known compounds. Theoretical computations showed that Y5N14 has an anion-driven metallicity, with the filled part of its conduction band formed by nitrogen p-states. The compressibility of Y5N14, determined on decompression down to ∼10 GPa, was found to be uncommonly high for dinitrides containing +3 cations (the bulk modulus K0 = 137(6) GPa).