dysprosium(III) Chloride
Properties
| State | Solid (hygroscopic; commonly hydrated) |
| Color | white to pale yellow |
| Solubility | Very soluble in water; soluble in alcohols |
| Melting Point | 774 °C (anhydrous) |
About dysprosium(III) Chloride
Dysprosium(III) chloride is the workhorse soluble Dy salt — pale yellow, viciously hygroscopic, and almost always sold as the hexahydrate because the anhydrous form is a genuine pain to obtain cleanly. Try to dehydrate DyCl3·6H2O by simple heating in air and you get DyOCl plus HCl rather than anhydrous DyCl3, a problem shared by the entire heavy-lanthanide chloride series. The standard workarounds are the NH4Cl method (heat the hydrate with a 6:1 excess of NH4Cl, which sublimes off the water as HCl·NH3 and leaves anhydrous DyCl3 behind) or vacuum sublimation at 800 °C under dynamic vacuum. Crystallographically the anhydrous chloride takes the AlCl3 layered structure with 6-coordinate Dy3+, while in aqueous solution the [Dy(H2O)9]3+ aqua ion is the dominant species — that 9-coordination tricapped trigonal prism is characteristic of the larger trivalent lanthanides. The most photogenic application of DyCl3 is in the strontium aluminate phosphor SrAl2O4:Eu2+,Dy3+, the bright green afterglow material in modern emergency exit signs. The Dy3+ acts as a charge-trap dopant: UV light pumps Eu2+, some carriers get caught in Dy3+ trap states, and they leak back out over hours to give the long persistent glow that ZnS:Cu (the old radium-replacement phosphor) couldn't match.
Where you'll encounter it
If you've ever opened a bottle of DyCl3·6H2O on the bench, you've seen it deliquesce into a pale-yellow puddle within minutes — that's not a mistake, it's a hexahydrate that wants to be a heptahydrate or just a solution. In a phosphor synthesis lab, you'd weigh DyCl3 alongside SrCO3, Al2O3, Eu2O3, and a bit of B2O3 flux, then fire under reducing atmosphere (5% H2/N2) at 1200-1400 °C to make the SrAl2O4:Eu,Dy that ends up in glow-in-the-dark watch dials and emergency signage. In a Schlenk-line organolanthanide lab, anhydrous DyCl3 is the entry point to Dy(Cp)3, Dy(Cp*)3, and the single-molecule magnets that have driven the magnetic-anisotropy literature for the past decade.
Common Uses
- Starting material for anhydrous Dy organometallics (cyclopentadienyl, amide complexes)
- Dopant precursor for SrAl2O4:Eu2+,Dy3+ long-afterglow phosphors in safety signage
- Co-dopant source in single-molecule magnet research (Dy3+ has the highest single-ion anisotropy)
- Feedstock for electrolytic production of dysprosium metal in molten chloride baths
- Lewis acid catalyst for selected acetalization and Diels-Alder reactions
- Reagent for Dy3+ separations via solvent extraction with organophosphorus extractants
- Precursor for Dy-doped scintillator and laser host crystal synthesis
- NMR shift reagent precursor for paramagnetic relaxation studies
Safety Information
GHS H315 (skin irritation) and H319 (eye irritation), Category 2/2A. Acute oral toxicity is moderate (LD50 ~3-5 g/kg in rat). The real workplace hazard is HCl evolution when the hydrate contacts skin moisture or warm humid air — wear nitrile gloves and weigh in a hood. No occupational exposure limit has been set specifically for Dy compounds; apply the dust control you would use for any respirable nuisance dust. Repeated lanthanide dust inhalation has been linked to pulmonary granulomas in occupational studies of rare-earth refinery workers.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals. We deliberately do not publish occupational exposure limits or other regulatory thresholds: those values are revised over time and differ between jurisdictions, so the only correct source is the current SDS and the regulations that apply where you work.