CaH3
CaH3 is a metallic calcium hydride phase that is primarily of interest for its structural complexity and behavior under extreme conditions.
About CaH3
CaH3 is a metallic hydride compound that represents a complex phase within the calcium-hydrogen system. Its metallic electronic character distinguishes it from many conventional insulating hydrides, making it a subject of significant interest in condensed matter physics and high-pressure research.
Despite its thermodynamic instability relative to more common phases, the compound has been extensively characterized across multiple databases. Its structural diversity highlights the intricate bonding behaviors possible when calcium and hydrogen are subjected to varying environmental conditions.
Key Properties
Cross-validated computational properties for CaH3, 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.
Reported Structures
Lowest-energy structures reported for CaH3, 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 | 0.00 | 0.3047 | -4.546 | 1.95 |
| P-1 (No. 2) | Triclinic | — | — | — | 0.88 |
| Cmcm (No. 63) | Orthorhombic | — | — | — | 1.33 |
| Cmcm (No. 63) | Orthorhombic | — | — | — | 1.40 |
| Cmcm (No. 63) | Orthorhombic | — | — | — | 1.47 |
| P1 (No. 1) | Triclinic | — | — | — | 0.93 |
| P1 (No. 1) | Triclinic | — | — | — | 1.01 |
| Cm (No. 8) | Monoclinic | — | — | — | 1.22 |
| C2/m (No. 12) | Monoclinic | — | — | — | 0.84 |
| P-1 (No. 2) | Triclinic | — | — | — | 0.92 |
| P-1 (No. 2) | Triclinic | — | — | — | 0.86 |
| P-1 (No. 2) | Triclinic | — | — | — | 1.05 |
Applications
Where CaH3 is used.
Frequently Asked Questions
Common questions about CaH3, answered from cross-validated data.
What is CaH3?
CaH3 is a metallic calcium hydride phase that is primarily of interest for its structural complexity and behavior under extreme conditions.
What is CaH3 used for?
What is the band gap of CaH3?
Is CaH3 a metal, semiconductor, or insulator?
Is CaH3 thermodynamically stable?
What is the crystal structure of CaH3?
What is the density of CaH3?
How many polymorphs of CaH3 are known?
What elements does CaH3 contain?
Where does the data for CaH3 come from?
How It Compares
Within the hydrogen storage hydrides class.
Unlike the highly stable and widely utilized CaH2, which serves as a standard reference in the hydrogen storage class, CaH3 exists in a more precarious thermodynamic state. While simpler hydrides like LiH or MgH2 are prized for their predictable storage capabilities, CaH3 is primarily studied for its unique metallic properties and structural variety rather than as a practical storage medium.
Related Compounds
Other Hydrogen Storage Hydrides in the database.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- mpaloe — Data from mpaloe.
- nomad — Data from NOMAD. Cite: Draxl & Scheffler, J. Phys. Mater. 2, 036001 (2019).
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
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