Erbium(III) bromide is an inorganic compound of erbium and bromide, with the formula ErBr3. The anhydrous compound is a rose-violet, hygroscopic solid, while the hexahydrate, ErBr3·6H2O, forms pink crystals.
Preparation Anhydrous erbium(III) bromide can be prepared from erbium(III) oxide using the ammonium-bromide route. In this method, the oxide is reacted with excess ammonium bromide, initially producing an ammonium bromide complex which decomposes on heating to give the anhydrous tribromide:
Er2O3 + 6 NH4Br → 2 ErBr3 + 6 NH3 + 3 H2O
The hexahydrate can be crystallized from an aqueous erbium bromide solution acidified with hydrobromic acid.
Properties Anhydrous compound Anhydrous ErBr3 is a rose-violet, hygroscopic crystalline solid.
It melts at about 923 °C according to modern compilations, although older measurements reported values near 950 °C. It is readily soluble in water but is moisture-sensitive in the anhydrous state.
Like other heavy rare-earth tribromides, molten ErBr3 has been investigated by neutron diffraction. The melt retains strong short-range Er–Br correlations but loses the long-range order of the crystalline phase.
Hexahydrate Erbium(III) bromide hexahydrate, ErBr3·6H2O, forms pink crystals.
Brown, Fletcher and Holah studied the crystallographic properties of a series of lanthanide tribromide hexahydrates and showed that the hydrated bromides form structural families related to one another across the lanthanide series.
The hydrate readily loses water on heating, but direct dehydration is liable to produce erbium oxybromide rather than pure anhydrous ErBr3; this is why ammonium-halide methods are preferred for preparation of oxygen-free anhydrous material.
Reactions Erbium(III) bromide reacts with lithium bromide at elevated temperature to form the ternary bromide Li3ErBr6:
ErBr3 + 3 LiBr → Li3ErBr6
Li3ErBr6 belongs to a family of lithium rare-earth bromides studied for their lithium-ion mobility.
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