Volume 104, Number 1, October 2013
|Number of page(s)||5|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||15 November 2013|
Pressure-induced polymerization of nitrogen in potassium azides
1 Institute of Condensed Matter Physics, Linyi University - Linyi 276005, PRC
2 Department of Physics and Materials Science, City University of Hong Kong - Hong Kong, SAR
3 Beijing Computational Science Research Center - Beijing, 100084, PRC
4 Department of Physics, Yancheng Institute of Technology - Yancheng, 224051, PRC
Received: 27 July 2013
Accepted: 3 October 2013
The phase transition and structural evolution of KN3 are systematically studied using first-principles density functional (DFT) methods and the particle swarm optimization (PSO) structure search algorithm under pressures up to 400 GPa. For the first time, we identify three stable phases with , and structure at pressures of 15.7, 41.4 and 298.6 GPa. The analysis of the crystal structures of three new predicted phases reveals that the transition of N3− ions goes from linear molecules to benzene-like rings and then to polymer chains induced by pressure. The study of atomic and electronic structures of three predicted phases reveals that the structural changes are accompanied and driven by the change of atomic orbital hybridization, first from sp to sp2, and then from sp2 to sp3. Our result provides a new view of the pressure-induced polymerization process of metal azides.
PACS: 61.50.Ks – Crystallographic aspects of phase transformations; pressure effects / 71.15.Mb – Density functional theory, local density approximation, gradient and other corrections / 71.20.-b – Electron density of states and band structure of crystalline solids
© EPLA, 2013
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