RbAlF4
RbAlF4 is a stable, insulating ternary fluoride compound used primarily in foundational materials research.
About RbAlF4
RbAlF4 is a thermodynamically stable inorganic compound that exists on the convex hull, indicating significant structural robustness. As a wide-gap insulator, it exhibits the characteristic electronic properties typical of complex fluoride systems, making it a subject of interest for fundamental materials science studies.
With multiple reported structures across major databases, this compound serves as a key reference point for understanding the coordination chemistry of aluminum and rubidium within a fluoride framework. Its stability profile suggests potential utility in specialized dielectric applications or as a precursor in solid-state synthesis.
Key Properties
Cross-validated computational properties for RbAlF4, 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.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of RbAlF4. 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 RbAlF4, 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. |
|---|---|---|---|---|---|
| — | — | 7.64 | 0.0000 | -3.609 | — |
| P4/mbm (No. 127) | tetragonal | 7.52 | 0.0000 | -3.573 | — |
| I4/mcm (No. 140) | tetragonal | 6.83 | 0.0000 | -5.701 | 3.72 |
| Pmmn (No. 59) | orthorhombic | 7.54 | 0.0001 | -3.572 | — |
| P4/mbm (No. 127) | tetragonal | 6.94 | 0.0003 | -5.701 | 3.84 |
| Pmmn (No. 59) | orthorhombic | 6.96 | 0.0004 | -5.700 | 3.85 |
| P4/mmm (No. 123) | tetragonal | 6.88 | 0.0010 | -5.700 | 3.75 |
| — | — | 7.66 | 0.0011 | -3.608 | — |
| — | — | 7.72 | 0.0038 | -3.605 | — |
| P4/mmm (No. 123) | tetragonal | 7.36 | 0.0053 | -3.567 | — |
| — | — | 7.81 | 0.0143 | -3.595 | — |
| — | — | 7.84 | 0.0166 | -3.592 | — |
Applications
Where RbAlF4 is used.
Frequently Asked Questions
Common questions about RbAlF4, answered from cross-validated data.
What is RbAlF4?
RbAlF4 is a stable, insulating ternary fluoride compound used primarily in foundational materials research.
What is RbAlF4 used for?
What is the band gap of RbAlF4?
Is RbAlF4 a metal, semiconductor, or insulator?
Is RbAlF4 thermodynamically stable?
What is the crystal structure of RbAlF4?
How many polymorphs of RbAlF4 are known?
What elements does RbAlF4 contain?
Where does the data for RbAlF4 come from?
How It Compares
As a distinct inorganic fluoride, RbAlF4 occupies a unique position in the landscape of aluminum-based ternary compounds. It serves as a representative example of how alkali metal incorporation stabilizes the aluminum-fluoride lattice, providing a baseline for studying structural diversity in related halide systems.
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)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
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