Lithium fluoride
Lithium fluoride (LiF) is an inorganic compound composed of lithium cations and fluoride anions, forming a white, odorless crystalline solid that occurs as a dry powder or cubic crystals. It is the least soluble among the alkali metal fluorides, with a solubility of approximately 0.134 g/100 g water at 25 °C, and exhibits high thermal stability with a melting point of 848 °C and a boiling point of 1673 °C.[1][2] Lithium fluoride has a molecular weight of 25.94 g/mol, a density of 2.64 g/cm³, and low hygroscopicity compared to other lithium halides. As a highly ionic substance, it possesses a high dielectric constant of about 9.0 and excellent transparency across ultraviolet (UV), visible, and infrared (IR) spectra, extending into the vacuum UV region down to 121 nm. However, it is a strong irritant to skin and eyes and toxic if ingested, classified as acutely toxic with hazard codes H301, H315, H319, and H335.[1][2] Due to its unique properties, lithium fluoride is used in ceramics and glass manufacturing as a flux, in optical components like UV windows and IR lenses, in thermoluminescent dosimeters for radiation detection, in molten salt mixtures for nuclear reactors, and as a precursor for lithium-ion battery electrolytes. Emerging applications include organic electronics and rechargeable batteries.[2][3]Properties
Physical properties
Lithium fluoride (LiF) is an inorganic compound with the molecular formula LiF and a molar mass of 25.939 g/mol.[1] It typically appears as a colorless or white crystalline solid, often in the form of cubic crystals or fine powder.[1] Key physical properties of lithium fluoride are summarized in the following table:| Property | Value | Conditions/Notes |
|---|---|---|
| Density | 2.640 g/cm³ | At 20 °C |
| Melting point | 848 °C (1,121 K) | - |
| Boiling point | 1,676 °C (1,949 K) | - |
| Refractive index (n_D) | 1.392 | At 0.6 μm wavelength |