Lithium metaborate is a chemical compound of lithium, boron, and oxygen with elemental formula LiBO2. It is often encountered as a hydrate, LiBO2·nH2O, where n is usually 2 or 4. However, these formulas do not describe the actual structure of the solids.
boric acid, lithium salt
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||49.751 g/mol|
|Appearance||white hygroscopic monoclinic crystals|
|Melting point||849 °C (1,560 °F; 1,122 K)|
|0.89 g/100 mL (0 °C) |
2.57 g/100 mL (20 °C)
11.8 g/100 mL (80 °C)
|Solubility||soluble in ethanol|
Heat capacity (C)
|59.8 J/mol K|
|51.3 J/mol K|
Std enthalpy of
Std enthalpy of
|NFPA 704 (fire diamond)|
|Safety data sheet (SDS)||External MSDS|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Lithium metaborate is one of the borates, a large family of salts (ionic compounds) with anions consisting of boron, oxygen, and hydrogen.
Lithium metaborate has several crystal forms.
The γ form is stable at 15 kbar and 950 °C. It has a polymeric cation consisting of a tridimensional regular array of [B(O−)4]− tetrahedra sharing oxygen vertices, alernating with lithium cations, each also surrounded by four oxygen atoms. The B-O distances are 148.3 pm, the Li-O distances are 196 pm.
Molten lithium metaborate, often mixed with lithium tetraborate Li2B4O7, is used to dissolve oxide samples for analysis by XRF, AAS, ICP-OES, ICP-AES, and ICP-MS, modern versions of classical bead test. The process may be used also to facilitate the dissolution of oxides in acids for wet analysis. Small amounts of lithium bromide] LiBr or lithium iodide LiI may be added as mold and crucible release agents.
Lithium metaborate dissolves acidic oxides MexOy with x < y, such as SiO2 Al2O3, SO3, P2O5, TiO2, Sb2O3, V2O5, WO3, and Fe2O3. Lithium tetraborate, on the other hand, dissolves basic oxides with x > y, such as CaO, MgO and other oxides of the alkali metals and alkaline earth metals. Most oxides are best dissolved in a mixture of the two lithium borate salts, for spectrochemical analysis.
- ^ David R. Lide (1998): Handbook of Chemistry and Physics, edition 87, pages 4–66. CRC Press. ISBN 0-8493-0594-2
- ^ M. Marezio and J. P. Remeika (1966): "Polymorphism of LiMO2 Compounds and High‐Pressure Single‐Crystal Synthesis of LiBO2". Journal of Chemical Physics, volume 44, issue 9, pages 3348-. doi:10.1063/1.1727236
- ^ Terrance D. Hettipathirana (2004): "Simultaneous determination of parts-per-million level Cr, As, Cd and Pb, and major elements in low level contaminated soils using borate fusion and energy dispersive X-ray fluorescence spectrometry with polarized excitation". Spectrochimica Acta Part B: Atomic Spectroscopy, volume 59, issue 2, pages 223-229. doi:10.1016/j.sab.2003.12.013
- ^ a b c Fernand Claisse (2003): "Fusion and fluxes". Comprehensive Analytical Chemistry: Sample Preparation for Trace Element Analysis, volume 41, pages 301-311.