NaS2
NaS2 is a stable, semiconducting binary compound formed from sodium and sulfur.
About NaS2
NaS2 is a binary compound composed of sodium and sulfur that exhibits semiconducting electronic characteristics. As a thermodynamically stable phase located on the convex hull, it represents a well-defined structural arrangement within its chemical system.
Its existence is supported by extensive structural data across multiple databases, highlighting its significance in fundamental materials research. This stability makes it an intriguing candidate for investigating the interplay between alkali metals and chalcogens in electronic applications.
Key Properties
Cross-validated computational properties for NaS2, aggregated across 5 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of NaS2. Tight agreement means computed properties can be trusted without re-running calculations.
Agreement ScoreA normalized confidence score summarizing how closely independent DFT databases agree. Higher scores mean tighter cross-source agreement.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for NaS2, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| — | — | 2.08 | 0.0000 | -0.815 | — |
| I-42d (No. 122) | tetragonal | 2.02 | 0.0000 | -7.250 | 2.16 |
| I-42d (No. 122) | tetragonal | 1.98 | 0.0000 | -0.695 | — |
| Amm2 (No. 38) | orthorhombic | 0.00 | 0.1150 | -0.580 | — |
| — | — | 0.00 | 0.2211 | -0.594 | — |
| Pmmm (No. 47) | orthorhombic | 0.00 | 0.2396 | -0.455 | — |
| — | — | 0.00 | 0.5755 | -0.240 | — |
| P6/mmm (No. 191) | hexagonal | 0.00 | 0.6295 | -0.065 | — |
| — | — | 0.00 | 0.8052 | -0.010 | — |
| — | — | 0.00 | 1.7571 | 0.942 | — |
| P1 (No. 1) | triclinic | — | — | — | 2.20 |
| P-1 (No. 2) | triclinic | — | — | — | 2.75 |
Frequently Asked Questions
Common questions about NaS2, answered from cross-validated data.
What is NaS2?
NaS2 is a stable, semiconducting binary compound formed from sodium and sulfur.
What is the band gap of NaS2?
Is NaS2 a metal, semiconductor, or insulator?
Is NaS2 thermodynamically stable?
What is the crystal structure of NaS2?
What is the density of NaS2?
How many polymorphs of NaS2 are known?
What elements does NaS2 contain?
Where does the data for NaS2 come from?
How It Compares
As a thermodynamically stable binary phase, NaS2 serves as a foundational reference point for understanding the structural diversity possible within sodium-sulfur systems. It occupies a distinct position in the landscape of semiconducting materials, providing a clear benchmark for future exploration of related alkali-chalcogenide compounds.
Data sources & attribution
- oqmd — Data from the OQMD (oqmd.org). Cite: Saal et al., JOM 65, 1501 (2013); Kirklin et al., npj Comp. Mater. 1, 15010 (2015). (CC-BY-4.0)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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