Related Experiment Videos
Polymerization of nitrogen in sodium azide
M I Eremets1, M Yu Popov, I A Trojan
1Max Planck Institute fur Chemie, Postfach 3060, 55020 Mainz, Germany.
The Journal of Chemical Physics
|July 23, 2004
Summary
High pressure transforms sodium azide (NaN(3)) into polymeric nitrogen. This nitrogen material retains its structure upon decompression, offering potential for new material applications.
Area of Science:
- Materials Science
- High-Pressure Physics
- Solid-State Chemistry
Background:
- Nitrogen's high-pressure behavior is crucial for understanding energetic materials.
- Sodium azide (NaN(3)) contains nitrogen in a molecularlike azide ion (N(3-)) form.
- Investigating phase transitions in NaN(3) under extreme conditions is key to novel nitrogen allotropes.
Purpose of the Study:
- To investigate the high-pressure transformations of nitrogen within sodium azide.
- To characterize the resulting nitrogen structures and their properties.
- To explore the potential for creating novel polymeric nitrogen materials.
Main Methods:
- Raman spectroscopy to analyze vibrational modes.
- Electrical conductivity measurements to detect electronic changes.
- Laser heating and shear deformation to induce and study phase transitions up to 160 GPa and 3300 K.
Main Results:
- A new phase appeared above 19 GPa, indicating strong azide ion coupling.
- Transformations at ~50 GPa and >120 GPa led to sample darkening and opacity.
- Azide molecular vibron disappearance above 120 GPa signaled a transition to a nonmolecular, amorphouslike nitrogen state.
- Laser heating and shear stress accelerated these transformations.
- Polymeric nitrogen structures were formed and could be preserved upon decompression.
Conclusions:
- Sodium azide transforms into polymeric nitrogen under high pressure.
- The resulting nonmolecular nitrogen exhibits an amorphouslike structure that can crystallize.
- Polymeric nitrogen from sodium azide can be preserved, suggesting potential for new material synthesis.