KBiF4
KBiF4 is a metastable, wide-gap insulating halide perovskite used in materials science research to explore the electronic and structural limits of fluoride-based compounds.
About KBiF4
KBiF4 is a complex fluoride-based compound that sits within the broader family of halide perovskite materials. As a wide-gap insulator, it exhibits distinct electronic behavior compared to the typical semiconducting members of this class, making it a subject of interest for fundamental research into structural diversity and optoelectronic tuning. Its metastable nature suggests that synthesis conditions are critical for stabilizing its various reported structural phases.
Because of its unique composition, this material is primarily investigated for its potential role in advanced photovoltaic architectures or as a dielectric component in thin-film devices. Its structural versatility, evidenced by multiple known configurations, allows researchers to probe the limits of the perovskite framework when incorporating heavy elements like bismuth alongside alkali metals.
Key Properties
Cross-validated computational properties for KBiF4, 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 KBiF4. 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 KBiF4, 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. |
|---|---|---|---|---|---|
| — | — | 5.17 | 0.0000 | -2.860 | — |
| Fd-3m (No. 227) | cubic | 3.38 | 0.0018 | -2.701 | — |
| — | — | 3.75 | 0.0403 | -2.820 | — |
| Fd-3m (No. 227) | cubic | 3.23 | 0.0413 | -4.962 | 5.18 |
| — | — | 4.83 | 0.0524 | -2.807 | — |
| Cm (No. 8) | monoclinic | 4.19 | 0.1454 | -4.858 | 4.85 |
| Cm (No. 8) | monoclinic | — | — | — | 5.02 |
| Cm (No. 8) | monoclinic | — | — | — | 5.11 |
| Fd-3m (No. 227) | cubic | — | — | — | 5.18 |
| Fd-3m (No. 227) | cubic | — | — | — | 5.45 |
| Fd-3m (No. 227) | cubic | — | — | — | 5.39 |
| Cm (No. 8) | monoclinic | — | — | — | 4.85 |
Applications
Where KBiF4 is used.
Frequently Asked Questions
Common questions about KBiF4, answered from cross-validated data.
What is KBiF4?
KBiF4 is a metastable, wide-gap insulating halide perovskite used in materials science research to explore the electronic and structural limits of fluoride-based compounds.
What is KBiF4 used for?
What is the band gap of KBiF4?
Is KBiF4 a metal, semiconductor, or insulator?
Is KBiF4 thermodynamically stable?
What is the crystal structure of KBiF4?
How many polymorphs of KBiF4 are known?
What elements does KBiF4 contain?
Where does the data for KBiF4 come from?
How It Compares
Within the halide perovskite photovoltaics class.
Unlike the highly conductive and widely studied CsPbBr3 or CsSnI3, which are favored for their efficient light-harvesting properties, KBiF4 functions as a wide-gap insulator. While many of its siblings in the halide perovskite class are optimized for charge transport, KBiF4 serves as a structural outlier that helps define the boundaries of stability and electronic performance within the perovskite landscape.
Related Compounds
Other Halide Perovskite Photovoltaics 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)
- 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.
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