Erbium(III) chloride

Erbium(III) chloride, is a violet solid with the formula ErCl3. It is used in the preparation of erbium metal. Erbium(III) chloride, is a violet solid with the formula ErCl3. It is used in the preparation of erbium metal. It is also found as a pink crystalline hexahydrate, CAS number . It has the interesting property that the pink colour is much more intense under the light from a fluorescent lamp, as may be seen from the picture. Anhydrous erbium(III) chloride is formed from the hexahydrate by heating under a strongly chlorinating atmosphere, such as chlorine or hydrogen chloride; otherwise erbium oxide chloride, ErOCl, is formed. An alternative preparation is to react the readily available Er2O3 with excess NH4Cl to make the intermediate salt (NH4)3ErCl6 plus both ammonia and water. This salt is stable with respect to hydrolysis and can be thermally decomposed under vacuum to yield anhydrous erbium(III) chloride with loss of ammonia and gaseous HCl.