Layered polymeric nitrogen in RbN3 at high pressures

Area of Science:

• Materials Science
• Solid State Physics
• Quantum Chemistry

Background:

• Understanding the behavior of nitrogen-rich compounds under extreme pressure is crucial for discovering novel materials.
• Rubidium azide (RbN3) is an ionic compound whose high-pressure structural evolution remains largely unexplored.

Purpose of the Study:

• To investigate the structural and electronic properties of RbN3 under high pressure up to 300 GPa.
• To identify new stable phases and elucidate the nitrogen's structural evolution.

Main Methods:

• Utilized particle swarm optimization structure searching.
• Employed density functional theory (DFT) calculations.
• Analyzed crystal structure and electronic properties.

Main Results:

• Identified three new stable phases of RbN3 at 30, 50, and 200 GPa with P-1, P6/mmm, and C2/m symmetries.
• Observed a transition in N3- ions from linear molecules to polymeric chains, rings, and layers.
• Revealed pressure-induced changes in nitrogen's orbital hybridization (sp to sp2 to sp3).
• Discovered transition metal-like properties in Rb atoms due to 4d orbital occupation and strong Rb-N hybridization.

Conclusions:

• The study completes the understanding of RbN3's structural evolution under pressure.
• Rubidium atoms exhibit transition element-like behavior in high-pressure RbN3 phases.
• The findings offer insights into the design of novel high-pressure materials.