AlCr2O4
AlCr2O4 is a semiconducting spinel oxide that serves as a research material for exploring catalytic properties and complex transition metal oxide structures.
About AlCr2O4
AlCr2O4 is a complex oxide belonging to the spinel family, characterized by its semiconducting electronic nature. Its structural framework allows for diverse coordination environments, making it a subject of interest for researchers investigating catalytic surface chemistry and transition metal behavior. While it exhibits multiple reported structural configurations, it is often categorized as a metastable phase due to its position relative to the thermodynamic ground state. This instability is a critical factor in its synthesis and potential application in high-performance catalytic systems where phase control is essential.
Key Properties
Cross-validated computational properties for AlCr2O4, 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.
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 AlCr2O4. 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 AlCr2O4, 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. |
|---|---|---|---|---|---|
| — | — | 0.00 | 0.0744 | -2.599 | — |
| R-3m (No. 166) | trigonal | 2.06 | 0.1269 | -8.626 | 4.28 |
| Fd-3m (No. 227) | cubic | 0.00 | 0.1284 | -2.308 | — |
| Fd-3m (No. 227) | cubic | 0.00 | 0.1284 | -2.308 | — |
| Fd-3m (No. 227) | cubic | 0.00 | 0.1419 | -8.611 | 4.37 |
| C2/c (No. 15) | monoclinic | 0.00 | 0.4614 | -8.292 | 4.32 |
| C2/c (No. 15) | monoclinic | 0.00 | 0.5046 | -8.248 | 4.33 |
| Fd-3m (No. 227) | cubic | — | — | — | 4.77 |
| Fd-3m (No. 227) | cubic | — | — | — | 4.37 |
| Fd-3m (No. 227) | cubic | — | — | — | 4.74 |
Applications
Where AlCr2O4 is used.
Frequently Asked Questions
Common questions about AlCr2O4, answered from cross-validated data.
What is AlCr2O4?
AlCr2O4 is a semiconducting spinel oxide that serves as a research material for exploring catalytic properties and complex transition metal oxide structures.
What is AlCr2O4 used for?
What is the band gap of AlCr2O4?
Is AlCr2O4 a metal, semiconductor, or insulator?
Is AlCr2O4 thermodynamically stable?
What is the crystal structure of AlCr2O4?
What is the density of AlCr2O4?
How many polymorphs of AlCr2O4 are known?
What elements does AlCr2O4 contain?
Where does the data for AlCr2O4 come from?
How It Compares
Within the spinel oxide catalysts class.
Within the broader class of spinel oxides and related transition metal oxides, AlCr2O4 occupies a unique position compared to highly stable, widely used insulators like MgAl2O4. While MgAl2O4 serves as a robust structural archetype, AlCr2O4 presents a more complex electronic landscape due to the presence of chromium, placing it closer in functional character to active perovskite-type catalysts like LaMnO3 or LaNiO3 rather than simple binary oxides like ZnO or NiO.
Related Compounds
Other Spinel Oxide Catalysts in the database.
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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