Lutetium(III) sulfate is an inorganic compound of lutetium and sulfuric acid with the chemical formula Lu2(SO4)3. It commonly crystallizes from aqueous solution as the octahydrate, Lu2(SO4)3·8H2O.
Preparation Lutetium(III) sulfate can be prepared by dissolving lutetium(III) oxide in sulfuric acid:
Lu2O3 + 3 H2SO4 → Lu2(SO4)3 + 3 H2O
Crystallization from aqueous solution gives the octahydrate.
The octahydrate can also be crystallized by evaporation of aqueous solutions containing lutetium(III) ions and sulfate ions. Crystallization from aqueous solution gives the octahydrate.
Properties Lutetium(III) sulfate is soluble in water. The octahydrate has a molar mass of 782.25 g/mol and forms colorless to white crystals.
Like the other heavy rare-earth sulfates, lutetium(III) sulfate exhibits retrograde solubility: its solubility decreases strongly as temperature increases. Between 25 and 95 °C, the octahydrate is the equilibrium solid phase in contact with saturated aqueous solutions.
Across the heavy rare-earth series from gadolinium to lutetium, sulfate solubility increases markedly with increasing atomic number; lutetium(III) sulfate is therefore substantially more soluble than the corresponding gadolinium or terbium sulfates at comparable temperatures.
At 20 °C, a solubility of approximately 42.3 g per 100 mL of water has been reported for the octahydrate.
A trihydrate, Lu2(SO4)3·3H2O, is also known. Its crystal structure is considerably more complex than that of the common octahydrate, containing three crystallographically distinct Lu3+ sites with coordination numbers of six and eight.
Reactions Lutetium(III) sulfate reacts with alkali hydroxides to precipitate lutetium(III) hydroxide:
Lu2(SO4)3 + 6 NaOH → 2 Lu(OH)3↓ + 3 Na2SO4
On strong heating, lutetium sulfate ultimately decomposes rather than boiling. Lutetium sulfate has also been used as a precursor for preparation of lutetium oxysulfate and lutetium oxide materials.
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