Caesium bromide
title: "Caesium bromide" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["caesium-compounds", "alkali-metal-bromides", "caesium-chloride-crystal-structure"] topic_path: "general/caesium-compounds" source: "https://en.wikipedia.org/wiki/Caesium_bromide" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
| Watchedfields = changed | verifiedrevid = 443321289 | ImageFile = CsCl polyhedra.png | ImageSize = | ImageFile1 = Caesium-bromide-3D-ionic.png | IUPACName = Cesium bromide | OtherNames = Cesium bromide, Caesium(I) bromide |Section1={{Chembox Identifiers | ChemSpiderID_Ref = | ChemSpiderID = 22994 | SMILES = [Cs+].[Br-] | InChIKey = LYQFWZFBNBDLEO-REWHXWOFAA | StdInChI_Ref = | StdInChI = 1S/BrH.Cs/h1H;/q;+1/p-1 | StdInChIKey_Ref = | StdInChIKey = LYQFWZFBNBDLEO-UHFFFAOYSA-M | CASNo = 7787-69-1 | CASNo_Ref = | EINECS = 232-130-0 | RTECS = FK9275000 | UNII = 06M25EDM3F | PubChem = 24592 | InChI = 1/BrH.Cs/h1H;/q;+1/p-1 |Section2={{Chembox Properties | Formula = CsBr | MolarMass = 212.809 g/mol | Appearance = White solid | Density = 4.43 g/cm3 | MeltingPtC = 636 | MeltingPt_ref = | BoilingPtC = 1300 | BoilingPt_ref = | Solubility = 1230 g/L (25 °C) Disputed. 420 g/L (11 °C) See References 560 /L (15°C) 1020 g/L (28.5 °C) 1180 g/L (31 °C) 1240 g/L (32.5 °C) 1380 g/L (35 °C) | RefractIndex = 1.8047 (0.3 μm) 1.6974 (0.59 μm) 1.6861 (0.75 μm) 1.6784 (1 μm) 1.6678 (5 μm) 1.6439 (20 μm) | MagSus = −67.2·10−6 cm3/mol |Section3={{Chembox Structure | CrystalStruct = CsCl, cP2 | SpaceGroup = Pmm, No. 221 | LattConst_a = 0.4291 nm | UnitCellFormulas = 1 | UnitCellVolume =0.0790 nm3 | Coordination = Cubic (Cs+) Cubic (Br−) |Section4={{Chembox Hazards | NFPA-H = 2 | NFPA-F = 0 | NFPA-R = 0 | GHSSignalWord=Warning | GHSPictograms= | HPhrases = | PPhrases = | FlashPt = Non-flammable | LD50 = 1400 mg/kg (oral, rat) |Section8={{Chembox Related | OtherAnions = Caesium fluoride Caesium chloride Caesium iodide Caesium astatide | OtherCations = Sodium bromide Potassium bromide Rubidium bromide Francium bromide
Caesium bromide or cesium bromide is an ionic compound of caesium and bromine with the chemical formula CsBr. It is a white or transparent solid with melting point at 636 °C that readily dissolves in water. Its bulk crystals have the cubic CsCl structure, but the structure changes to the rocksalt type in nanometer-thin film grown on mica, LiF, KBr or NaCl substrates.
Synthesis
Caesium bromide can be prepared via neutralization reactions: : CsOH + HBr → CsBr + H2O : Cs2(CO3) + 2 HBr → 2 CsBr + H2O + CO2 It can also be prepared by direct synthesis: : 2 Cs + Br2 → 2 CsBr The direct synthesis is a vigorous reaction of caesium with bromine. Due to its high cost, it is not used for preparation.
Uses
Caesium bromide is sometimes used in optics as a beamsplitter component in wide-band spectrophotometers.
References
Cited sources
References
- Haynes, p. 4.57
- Haynes, p. 10.240
- Haynes, p. 4.132
- (1964). "Elastic Constants of CsBr and CsI from 4.2K to Room Temperature". Journal of Applied Physics.
- [https://pubchem.ncbi.nlm.nih.gov/#tab/sidsrcname=ChemIDplus&query=7787-69-1&input_type=text Caesium bromide]. nlm.nih.gov
- (1951). "Polymorphism of cesium and thallium halides". Acta Crystallographica.
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