It occurs through nearest-neighbor jumps of lattice vacancies, and the mobility is much higher for the Cl − than Cs + vacancies. The conductivity has a value of the order 10 −7 S/cm at 300 ☌. Caesium chloride has also a relatively high solubility in formic acid (1077 g/L at 18 ☌) and hydrazine medium solubility in methanol (31.7 g/L at 25 ☌) and low solubility in ethanol (7.6 g/L at 25 ☌), sulfur dioxide (2.95 g/L at 25 ☌), ammonia (3.8 g/L at 0 ☌), acetone (0.004% at 18 °С), acetonitrile (0.083 g/L at 18 °С), ethylacetates and other complex ethers, butanone, acetophenone, pyridine and chlorobenzene.ĭespite its wide band gap of about 8.35 eV at 80 K, caesium chloride weakly conducts electricity, and the conductivity is not electronic but ionic. In contrast to sodium chloride and potassium chloride, caesium chloride readily dissolves in concentrated hydrochloric acid. The crystals are very hygroscopic and gradually disintegrate at ambient conditions. It readily dissolves in water with the maximum solubility increasing from 1865 g/L at 20 ☌ to 2705 g/L at 100 ☌. Physical propertiesĬaesium chloride is colorless in the form of large crystals and white when powdered. Upon heating to above 450 ☌, the normal caesium chloride structure (α-CsCl) converts to the β-CsCl form with the rocksalt structure ( space group Fm 3m). When both ions are similar in size ( Cs + ionic radius 174 pm for this coordination number, Cl − 181 pm) the CsCl structure is adopted, when they are different (Na + ionic radius 102 pm, Cl − 181 pm) the sodium chloride structure is adopted. In contrast, the other alkaline halides have the sodium chloride (rocksalt) structure. This structure is shared with CsBr and CsI and many binary metallic alloys. The chloride atoms lie upon the lattice points at the edges of the cube, while the caesium atoms lie in the holes in the center of the cubes.
The caesium chloride structure adopts a primitive cubic lattice with a two-atom basis, where both atoms have eightfold coordination.
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