Al2FeS4
Al2FeS4 is a semiconducting ternary sulfide that exists as a metastable phase within the aluminum-iron-sulfur material system.

About Al2FeS4
Al2FeS4 is a ternary sulfide composed of aluminum, iron, and sulfur. As a semiconducting material, it represents a complex arrangement of elements that has been the subject of structural investigation across multiple databases. Its electronic properties make it a point of interest for researchers exploring new chalcogenide frameworks.
Because this compound sits above the thermodynamic hull, it is considered a metastable phase. This status suggests that while it may be difficult to synthesize in bulk, it offers unique opportunities for studying metastable pathways and structural diversity in complex sulfide systems.
Key Properties
Cross-validated computational properties for Al2FeS4, aggregated across 3 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.
Reported Structures
Lowest-energy structures reported for Al2FeS4, 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. |
|---|---|---|---|---|---|
| R-3m (No. 166) | trigonal | 0.63 | 0.1267 | -5.704 | 3.02 |
| R3m (No. 160) | trigonal | 0.00 | 0.1583 | -5.673 | 2.86 |
| R-3m (No. 166) | — | — | — | — | — |
| R3m (No. 160) | — | — | — | — | — |
| — | — | — | — | — | 2.67 |
Applications
Where Al2FeS4 is used.
Frequently Asked Questions
Common questions about Al2FeS4, answered from cross-validated data.
What is Al2FeS4?
Al2FeS4 is a semiconducting ternary sulfide that exists as a metastable phase within the aluminum-iron-sulfur material system.
What is Al2FeS4 used for?
What is the band gap of Al2FeS4?
Is Al2FeS4 a metal, semiconductor, or insulator?
Is Al2FeS4 thermodynamically stable?
What is the crystal structure of Al2FeS4?
What is the density of Al2FeS4?
How many polymorphs of Al2FeS4 are known?
What elements does Al2FeS4 contain?
Where does the data for Al2FeS4 come from?
How It Compares
As a relatively rare ternary sulfide, Al2FeS4 serves as an example of the structural complexity possible within metal-sulfide systems. Unlike more common, highly stable binary sulfides, this compound highlights the challenges and scientific value of investigating metastable phases that exist outside the standard thermodynamic ground state.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
- omat24 — Data from OMat24 (Meta FAIR). Cite: Barroso-Luque et al., arXiv 2410.12771 (2024).
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