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Reversible phase transitions in Na2S under pressure: a comparison with the cation array in Na2SO4
A Vegas1, A Grzechnik, K Syassen
1Max-Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany. avegas@iqfr.csic.es
Acta Crystallographica. Section B, Structural Science
|March 23, 2001
Summary
Disodium sulfide (Na2S) exhibits structural changes under high pressure. It transitions to anticotunnite and Ni2In-type structures, offering insights into material behavior and crystal chemistry.
Area of Science:
- Materials Science
- Solid-State Chemistry
- High-Pressure Physics
Background:
- Disodium sulfide (Na2S) is an antifluorite compound with potential applications.
- Understanding its structural behavior under pressure is crucial for materials science.
Purpose of the Study:
- To investigate the pressure-induced structural phase transitions of Na2S.
- To characterize the new crystal structures adopted by Na2S under compression.
Main Methods:
- In situ synchrotron X-ray diffraction experiments were conducted.
- Experiments utilized a diamond anvil cell at room temperature.
- Full Rietveld refinements were employed for structural analysis.
Main Results:
- Na2S undergoes a phase transition to the orthorhombic anticotunnite (PbCl2) structure around 7 GPa.
- A second transition to the Ni2In-type structure occurs near 16 GPa.
- Lattice parameters for both high-pressure phases were determined.
Conclusions:
- The study reveals two distinct pressure-induced structural phases in Na2S.
- The Ni2In-type structure in Na2S is analogous to cation arrangements in ternary oxides like Na2SO4.
- This highlights a relationship between binary compound topology and ternary oxide structures.