On the crystal chemistry of inorganic nitrides: crystal-chemical parameters, bonding behavior, and opportunities in the exploration of their compositional space

Abstract

The scarcity of nitrogen in Earth’s crust, combined with challenging synthesis, have made inorganic nitrides a relatively unexplored class of compounds compared to their naturally abundant oxide counterparts. To facilitate...

Single‐Bonded Cubic AsN from High‐Pressure and High‐Temperature Chemical Reactivity of Arsenic and Nitrogen

“…[22] Taking advantage of the high density conditions generated by diamond anvil cells (DACs) and high temperature-quenching rate inherent to laser heating technique,t his approach has dramatically changed the idea of the stability and inertness of the N 2 molecule, expanding our knowledge about the chemistry of Na nd revealing the existence of an entire new class of N-rich materials recoverable at room Tond ecompression to low or even ambient pressure. [23][24][25][26][27] These experimental evidences nicely fit with recent studies [2,17,28] which have explored new compositional spaces for crystalline inorganic nitrides,s uggesting the existence of alarge variety of compounds to be discovered and identifying them as ideal candidates to be potentially recovered at ambient conditions as thermodynamically metastable materials.I ndeed, according to the thermodynamic scale of metastability for crystalline inorganic materials proposed by Sun et al, [28] nitrides feature the highest enthalpy above the ground state (at 0K and zero pressure) and the highest cohesive energy among chalcogenides,p nictides and halides. In particular,t he ability of forming strong localized covalent bonds with low ionic character can lock the stabilization of high energy structures against unfavorable atomic arrangements,p reventing their decomposition or their transformation to the ground state polymorph, and likely allowing the recovery at ambient conditions of new thermodynamically metastable nitrides of relevant technological interest.…”

“…Even if very few datasets are available in literature for stereoactive electron lone pairs in nitrides in general and no information about any compound made of As and N was contained in the analyzed dataset, a recent extensive analysis of structural parameters and valence‐bond properties performed by Gagné, [2] focused at identifying new compositional spaces for the synthesis of functional inorganic nitrides, has predicted an optimal matching of atomic orbital energy to originate lone pair stereoactivity in AsN. Considering that lone pair stereoactivity is favored by the higher s character of the antibonding orbital, the smaller value of the N‐As‐N bond angles, compared to the As‐N‐As ones, indicate for As a higher p orbital bonding contribution to the formation of the As−N bonds and a higher s character of the corresponding antibonding orbital with respect to N, which is a condition expected to favor orbital mixing and hence lone pair stereoactivity [2, 60] …”

“…Indeed, according to the thermodynamic scale of metastability for crystalline inorganic materials proposed by Sun et al., [28] nitrides feature the highest enthalpy above the ground state (at 0 K and zero pressure) and the highest cohesive energy among chalcogenides, pnictides and halides. In particular, the ability of forming strong localized covalent bonds with low ionic character can lock the stabilization of high energy structures against unfavorable atomic arrangements, preventing their decomposition or their transformation to the ground state polymorph, and likely allowing the recovery at ambient conditions of new thermodynamically metastable nitrides of relevant technological interest [2, 28] …”

“…Nitrogen and arsenic are the first and the third element of Group 15 of the periodic table, whose members, named pnictogens, have ns 2 np 3 outer shell electronic orbital configuration. N and As combine with metal and non‐metal elements to form binary and ternary compounds, [1] which are of extreme interest for a variety of energy and technology related applications [2, 3] . They are also known to combine with P, the second element in group 15, forming binary compounds: α‐P 3 N 5 , [4] γ‐P 3 N 5 [5] in the case of N and As x P 1− x [6] in the case of As.…”

“…Thei nvestigation of the chemical reactivity between As and Nunder extreme pressure and temperature conditions is not only important to address specific issues about fundamental pnictogens chemistry but is currently relevant to the possibility of taking advantage of pressure to design and synthesize innovative materials of energetic and technological relevance,p otentially recoverable at ambient conditions in their stable or metastable states,a ss uggested by theoretical indications.Examples include nitrides, [2,28] N-doped arsenene based materials, [38][39][40][41] high energy density materials [23] and advanced thermoelectrics. [42]…”