Dysprosium(III) sulfate is an inorganic compound with the chemical formula . It commonly crystallizes from aqueous solution as the yellow octahydrate, .
Preparation Dysprosium(III) sulfate can be prepared by dissolving dysprosium(III) oxide in sulfuric acid:
Dy2O3 + 3 H2SO4 → Dy2(SO4)3 + 3 H2O
Crystallization from aqueous solution gives the octahydrate. The anhydrous form can be obtained by heating the hydrate to about 360 °C.
Properties Dysprosium(III) sulfate octahydrate crystallizes in the monoclinic crystal system, in space group C2/c (No. 15), with four formula units per unit cell. Its lattice parameters at room temperature are a = 13.469 Å, b = 6.695 Å, c = 18.202 Å and β = 102.06°.
Like other heavy rare-earth sulfates, dysprosium(III) sulfate exhibits retrograde solubility, with its solubility in water decreasing as temperature increases. Measurements between 25 and 95 °C found the octahydrate to be the equilibrium solid phase throughout this temperature range.
In sulfuric acid solutions, the solubility initially increases with acid concentration and passes through a maximum, behaviour attributed to sulfate–bisulfate equilibria and sulfate complex formation.
Thermal decomposition On heating, dysprosium(III) sulfate octahydrate loses its water of crystallization in stages to form anhydrous Dy2(SO4)3.
Further heating gives different products depending on the atmosphere. Under a reducing carbon monoxide atmosphere, dysprosium oxysulfide, Dy2O2S, forms at about 1150 K. In air, dysprosium oxysulfate, Dy2O2SO4, is formed at about 1310 K.
The Dy2O2S produced by this route exhibits yellow photoluminescence arising from Dy3+ transitions and has been investigated as a phosphor material.
Related compounds A dysprosium sulfate-based coordination polymer, , has been characterized by single-crystal X-ray diffraction. It is of research interest as a proton-conducting material.
A hydroxysulfate and ethylsulfate have also been characterized.
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