CuN₁₀: a high-energy-density pentazolate with an antiferromagnetic state

Area of Science:

• Materials Science
• Computational Chemistry
• Inorganic Chemistry

Background:

• Pentazolates are of interest due to their green nature and high energy density.
• The role of spin electrons in pentazolate stability remains unclear.

Purpose of the Study:

• Investigate the energy landscape of copper(II) pentazolate using first principles calculations.
• Elucidate the physical role of spin electrons in the stability of copper(II) pentazolate compounds.

Main Methods:

• Constrained first principles structure search.
• Density of States (DOS) analysis.
• Analysis of electron configuration and hybridization.

Main Results:

• The most stable phase, P212121-CuN10, features dsp2 hybridized Cu atoms and a square-layered configuration.
• Unpaired electrons on Cu2+ initially cause instability by creating a Van Hove singularity in the DOS.
• Electron rearrangement leads to an antiferromagnetic state, lowering the DOS at the Fermi level and stabilizing the structure by 0.128 eV/formula.

Conclusions:

• Spin electrons play a crucial role in stabilizing copper(II) pentazolate structures.
• P212121-CuN10 exhibits a high energy density (4.05 kJ g-1), surpassing related compounds.
• This compound is a promising candidate for high-energy-density material applications.