KI
Potassium iodide · KI
Potassium iodide is a stable, insulating salt widely used in medical applications, radiation protection, and optical technologies.
About Potassium iodide
Potassium iodide is a fundamental inorganic salt characterized by its wide-gap insulating electronic structure. As a thermodynamically stable compound, it maintains structural integrity under standard conditions and is highly valued for its chemical reliability in various industrial and scientific processes.
This material is widely recognized for its role in health and safety applications, particularly in thyroid protection during radiological emergencies. Beyond its medical utility, its optical properties make it a key component in the manufacturing of specialized radiation detectors and high-performance optical lenses.
Key Properties
Cross-validated computational properties for Potassium iodide, 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 KI, 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 | 3.85 | 0.0000 | -2.998 | 3.10 |
| Cmcm (No. 63) | orthorhombic | 3.75 | 0.0193 | -2.978 | 2.97 |
| Pnma (No. 62) | orthorhombic | 4.07 | 0.0202 | -2.978 | 2.95 |
| P63/mmc (No. 194) | hexagonal | 4.44 | 0.0204 | -2.977 | 3.09 |
| Pm-3m (No. 221) | cubic | 3.24 | 0.0603 | -2.937 | 3.49 |
| Cm (No. 8) | Monoclinic | — | — | — | 2.12 |
| P63/mmc (No. 194) | — | — | — | — | — |
| Pm-3m (No. 221) | — | — | — | — | — |
| Pnma (No. 62) | Orthorhombic | — | — | — | 2.95 |
| Pnma (No. 62) | Orthorhombic | — | — | — | 3.01 |
| Pnma (No. 62) | Orthorhombic | — | — | — | 3.07 |
| Cmcm (No. 63) | Orthorhombic | — | — | — | 1.31 |
Applications
Where Potassium iodide is used.
Frequently Asked Questions
Common questions about Potassium iodide, answered from cross-validated data.
What is KI?
Potassium iodide is a stable, insulating salt widely used in medical applications, radiation protection, and optical technologies.
What is KI used for?
What is the band gap of KI?
Is KI a metal, semiconductor, or insulator?
Is KI thermodynamically stable?
What is the crystal structure of KI?
What is the density of KI?
How many polymorphs of KI are known?
What elements does KI contain?
Where does the data for KI come from?
How It Compares
As a primary halide salt, potassium iodide serves as a benchmark for stability and performance within its class of alkali metal halides, setting the standard for ionic bonding characteristics and chemical reactivity in this group.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- mpaloe — Data from mpaloe.
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
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