HfI4
hafnium(IV) iodide · hafnium tetraiodide
Hafnium(IV) iodide is a stable, insulating inorganic halide used primarily as a precursor in the chemical transport and purification of hafnium metal.
About hafnium(IV) iodide
Hafnium(IV) iodide is a thermodynamically stable halide compound characterized by its insulating electronic nature. It serves as a critical intermediate in the chemical processing of transition metals, leveraging its volatility and reactivity to facilitate high-purity material synthesis. The compound is highly regarded for its role in specialized chemical vapor transport applications. Its structural versatility is highlighted by a significant number of reported configurations across various databases, reflecting its importance in inorganic chemistry research.
Key Properties
Cross-validated computational properties for hafnium(IV) iodide, aggregated across 5 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 HfI4. 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 HfI4, 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. |
|---|---|---|---|---|---|
| — | — | 2.51 | 0.0000 | -1.047 | — |
| C2/c (No. 15) | monoclinic | 2.31 | 0.0000 | -4.427 | 5.24 |
| C2/c (No. 15) | monoclinic | 2.05 | 0.0000 | -0.915 | — |
| — | — | 2.33 | 0.0008 | -1.047 | — |
| Pa-3 (No. 205) | cubic | 3.29 | 0.0300 | -4.397 | 4.56 |
| — | — | 2.27 | 0.0301 | -1.017 | — |
| — | — | 3.43 | 0.0331 | -1.014 | — |
| — | — | 0.70 | 0.0615 | -0.986 | — |
| P-1 (No. 2) | triclinic | — | — | — | 12.68 |
| C2/c (No. 15) | monoclinic | — | — | — | 4.82 |
| P-1 (No. 2) | triclinic | — | — | — | 9.83 |
| P-1 (No. 2) | triclinic | — | — | — | 4.33 |
Applications
Where hafnium(IV) iodide is used.
Frequently Asked Questions
Common questions about hafnium(IV) iodide, answered from cross-validated data.
What is HfI4?
Hafnium(IV) iodide is a stable, insulating inorganic halide used primarily as a precursor in the chemical transport and purification of hafnium metal.
What is HfI4 used for?
What is the band gap of HfI4?
Is HfI4 a metal, semiconductor, or insulator?
Is HfI4 thermodynamically stable?
What is the crystal structure of HfI4?
What is the density of HfI4?
How many polymorphs of HfI4 are known?
What elements does HfI4 contain?
Where does the data for HfI4 come from?
How It Compares
As a stable binary halide, hafnium(IV) iodide represents a fundamental building block in the study of group four metal halides. It functions as a primary reagent for vapor-phase transport processes, providing a stable pathway for the isolation and refinement of hafnium compared to more complex or less stable halide counterparts.
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.
- 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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