Ca4Cu4O8
Ca4Cu4O8 has a DFT band gap of 0.03–0.67 eV across 26 reported structures in 17 space groups; its lowest-energy polymorph is tetragonal (I41/a (No. 88)). Cross-validated across 3 computational databases.
At a glance
Key Properties
Cross-validated computational properties for Ca4Cu4O8, 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.
0.03–0.67 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.
26
3 databases, 17 space groups
Crystallography
Reported Structures
Lowest-energy structures reported for Ca4Cu4O8, 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. |
|---|---|---|---|---|---|
| I41/a (No. 88) | tetragonal | 0.67 | 0.0000 | -5.995 | 5.14 |
| P4/mmm (No. 123) | tetragonal | 0.00 | 0.0156 | -6.127 | 4.83 |
| Pbcm (No. 57) | orthorhombic | 0.44 | 0.0243 | -5.971 | 4.93 |
| P21212 (No. 18) | orthorhombic | 0.00 | 0.0697 | -6.073 | 4.63 |
| Cmmm (No. 65) | orthorhombic | 0.00 | 0.0701 | -6.073 | 4.52 |
| I41/amd (No. 141) | tetragonal | 0.58 | 0.0987 | -5.897 | 4.02 |
| P-1 (No. 2) | triclinic | 0.03 | 0.1198 | -6.023 | 4.25 |
| P-1 (No. 2) | triclinic | 0.00 | 0.1307 | -6.012 | 4.41 |
| P-1 (No. 2) | triclinic | 0.09 | 0.1474 | -5.995 | 4.13 |
| P21 (No. 4) | monoclinic | 0.10 | 0.1681 | -5.827 | 4.13 |
| Cmcm (No. 63) | orthorhombic | 0.00 | 0.1774 | -5.818 | 5.37 |
| Pmmn (No. 59) | orthorhombic | 0.00 | 0.1790 | -5.816 | 4.72 |
Reference
Frequently Asked Questions
Common questions about Ca4Cu4O8, answered from cross-validated data.
What is the band gap of Ca4Cu4O8?
Ca4Cu4O8 has a DFT-computed band gap of 0.03–0.67 eV across 26 reported structures.
More questions
Is Ca4Cu4O8 a metal, semiconductor, or insulator?
With a band gap up to 0.67 eV it is a semiconductor.
Is Ca4Cu4O8 thermodynamically stable?
Yes — Ca4Cu4O8 sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of Ca4Cu4O8?
The lowest-energy reported polymorph of Ca4Cu4O8 is tetragonal symmetry, space group I41/a (No. 88).
What is the density of Ca4Cu4O8?
The computed density of the ground-state structure of Ca4Cu4O8 is 5.14 g/cm³.
How many polymorphs of Ca4Cu4O8 are known?
26 structures of Ca4Cu4O8 are reported across 3 databases, spanning 17 distinct space groups.
What elements does Ca4Cu4O8 contain?
Ca4Cu4O8 contains Ca, Cu, and O (3 elements).
Where does the data for Ca4Cu4O8 come from?
Ca4Cu4O8 data is cross-referenced from materials_project, omat24, aflow.
Explore
Related Compounds
Other Spinel Oxide Catalysts in the database.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- omat24 — Data from OMat24 (Meta FAIR). Cite: Barroso-Luque et al., arXiv 2410.12771 (2024).
- aflow — Data from AFLOW. Cite: Curtarolo et al., Comp. Mater. Sci. 58, 218 (2012).
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