CaS
Calcium sulfide · Hepar calcis, Sulfurated lime
Calcium sulfide is an inorganic compound that appears as a white or yellowish powder. It is primarily utilized in industrial processes and as a component in specialized chemical applications.
CaS
Overview
Key Properties
Cross-validated computational properties for Calcium sulfide, aggregated across 4 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.
2.38 eV
Range across DFT structures
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.
0.000 eV/atom
Best (lowest) across sources
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.
On hull (stable)
2 DFT sources
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
147
4 databases, 28 space groups
Validation
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of CaS. 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.
1.00 / 1.00
Trust tier: medium
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
0.000 eV
EAH spread across sources
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
2
jarvis, materials_project
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
All match
Crystallography
Reported Structures
Lowest-energy structures reported for CaS, 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. |
|---|---|---|---|---|---|
| Fm-3m (No. 225) | cubic | 2.38 | 0.0000 | -9.972 | 2.58 |
| Pm (No. 6) | Monoclinic | — | — | — | 1.87 |
| P-1 (No. 2) | Triclinic | — | — | — | 1.11 |
| P-1 (No. 2) | Triclinic | — | — | — | 1.35 |
| P21/m (No. 11) | Monoclinic | — | — | — | 3.33 |
| Pnma (No. 62) | Orthorhombic | — | — | — | 2.45 |
| Pnma (No. 62) | Orthorhombic | — | — | — | 2.61 |
| C2/m (No. 12) | Monoclinic | — | — | — | 2.02 |
| C2/m (No. 12) | Monoclinic | — | — | — | 2.02 |
| C2/m (No. 12) | Monoclinic | — | — | — | 2.03 |
| P21/m (No. 11) | Monoclinic | — | — | — | 2.00 |
| P-1 (No. 2) | Triclinic | — | — | — | 1.05 |
Synthesis
Synthesis Routes
Literature-extracted synthesis procedures targeting CaS.
Sol-Gel
Procedure available · ceder_solid_state
Sol-Gel
Procedure available · ceder_solid_state
Uses
Applications
Where Calcium sulfide is used.
Luminous paintsDepilatory agentsOre flotationWater treatment
Reference
Frequently Asked Questions
Common questions about Calcium sulfide, answered from cross-validated data.
What is CaS?
Calcium sulfide is an inorganic compound that appears as a white or yellowish powder. It is primarily utilized in industrial processes and as a component in specialized chemical applications.
More questions
What is CaS used for?
Calcium sulfide (CaS) is used in luminous paints, depilatory agents, ore flotation, and water treatment.
What is the band gap of CaS?
Calcium sulfide (CaS) has a DFT-computed band gap of 2.38 eV across 147 reported structures.
Is CaS a metal, semiconductor, or insulator?
With a band gap up to 2.38 eV it is a semiconductor.
Is CaS thermodynamically stable?
Yes — Calcium sulfide (CaS) sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of CaS?
The lowest-energy reported polymorph of Calcium sulfide (CaS) is cubic symmetry, space group Fm-3m (No. 225).
What is the density of CaS?
The computed density of the ground-state structure of Calcium sulfide (CaS) is 2.58 g/cm³.
How many polymorphs of CaS are known?
147 structures of CaS are reported across 4 databases, spanning 28 distinct space groups.
How is CaS synthesized?
Literature-reported routes for CaS include sol-gel (2 procedures documented).
What elements does CaS contain?
Calcium sulfide (CaS) contains Ca and S (2 elements).
Where does the data for CaS come from?
CaS data is cross-referenced from materials_project, mpaloe, jarvis.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- mpaloe — Data from mpaloe.
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
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