NaS
NaS is a thermodynamically stable semiconducting compound formed from sodium and sulfur.
About NaS
NaS is a semiconducting material composed of sodium and sulfur. As a thermodynamically stable phase located on the convex hull, it represents a robust configuration within its chemical system, making it a subject of significant interest for structural studies.
With a high volume of reported structures across major databases, this compound serves as a key reference point for understanding sodium-sulfur interactions. Its electronic character positions it as a relevant candidate for exploring semiconductor behavior in binary alkali-chalcogen systems.
Key Properties
Cross-validated computational properties for NaS, 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 NaS. 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 NaS, 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. |
|---|---|---|---|---|---|
| — | — | 1.35 | 0.0000 | -1.035 | — |
| P63/mmc (No. 194) | hexagonal | 1.28 | 0.0000 | -0.969 | — |
| P63/mmc (No. 194) | hexagonal | 1.26 | 0.0000 | -6.803 | 2.09 |
| P-62m (No. 189) | hexagonal | 0.88 | 0.0023 | -6.801 | 2.07 |
| — | — | 1.00 | 0.0034 | -1.032 | — |
| P-62m (No. 189) | hexagonal | 1.06 | 0.0078 | -0.961 | — |
| Pmmm (No. 47) | orthorhombic | 0.00 | 0.1819 | -0.787 | — |
| — | — | 0.00 | 0.3045 | -0.730 | — |
| Pm-3m (No. 221) | cubic | 0.00 | 0.3261 | -0.643 | — |
| Pm-3m (No. 221) | cubic | 0.00 | 0.3753 | -6.428 | 2.32 |
| — | — | 0.00 | 0.3772 | -0.658 | — |
| P-6m2 (No. 187) | hexagonal | 0.00 | 0.3879 | -0.581 | — |
Applications
Where NaS is used.
Patent Landscape
5 patents reference NaS or close compositional variants.
| Patent | Title | Assignee | Granted |
|---|---|---|---|
| 5705289 | Process and apparatus for peeling outer tubes from spent NaS cells | — | — |
| 5778503 | Apparatus for disposing of spent NaS cells | — | — |
| 5785732 | process and apparatus for recovering Na from spent NaS cells | — | — |
| 5587252 | Process for disposing of spent NaS cells | — | — |
| 5600879 | Process and apparatus for peeling outer tubes from spent NaS cells by cutting and applying an impact force | — | — |
Frequently Asked Questions
Common questions about NaS, answered from cross-validated data.
What is NaS?
NaS is a thermodynamically stable semiconducting compound formed from sodium and sulfur.
What is NaS used for?
What is the band gap of NaS?
Is NaS a metal, semiconductor, or insulator?
Is NaS thermodynamically stable?
How many polymorphs of NaS are known?
What elements does NaS contain?
Where does the data for NaS come from?
How It Compares
As a thermodynamically stable binary compound, NaS serves as a foundational example of how sodium and sulfur organize into distinct structural phases, providing a baseline for investigating the broader landscape of alkali-metal sulfides.
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)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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