Erbium(III) Fluoride
Properties
| State | Solid |
| Color | Pink |
| Solubility | Essentially insoluble in water; insoluble in organic solvents |
| Melting Point | 1150 °C |
| Boiling Point | 2200 °C |
About Erbium(III) Fluoride
Erbium(III) fluoride is the pink, water-insoluble counterpart of pink, water-soluble ErCl3 — both salts get their color from the same Er3+ f-f transitions, but the fluoride lattice is too stable to dissolve. ErF3 crystallizes in the β-YF3 orthorhombic structure (space group Pnma), the same heavy-lanthanide trifluoride structure type as DyF3, melts at 1150 °C, and resists hydrolysis even in boiling water — its Ksp is around 10^-24. That insolubility is the practical reason ErF3 is the dopant of choice for ZBLAN fluoride-glass fiber amplifiers, where the fluoride matrix needs to stay chemically intact during glass melting at 800-900 °C and during fiber drawing. The reason anyone cares about Er-doped fiber at all is the 4I13/2 → 4I15/2 transition near 1530 nm, which happens to be the wavelength of minimum loss in silica fiber. In silica, that transition is broadened by Si-O phonons to about 30 nm of usable gain bandwidth — fine for early EDFAs. In ZBLAN, with phonon energies roughly half of silica's, the gain spectrum is broader and flatter (50-80 nm), supporting much denser DWDM channel counts and higher per-fiber capacity. ErF3 is also the standard Yb-codoped upconverter — Yb3+ harvests 980 nm pump light and feeds energy sequentially to Er3+, populating high-lying levels that emit green at 525/545 nm and red at 660 nm. That two-photon upconversion is what powers anti-counterfeiting inks on currency and pharmaceutical packaging.
Where you'll encounter it
If you've handled ZBLAN fluoride-glass preforms in a fiber-laser lab, you've worked with ErF3 — typical doping levels are 0.5-2 mol% in the ZrF4-BaF2-LaF3-AlF3-NaF host, hand-blended as fluoride powders and melted under reactive atmosphere. The resulting fibers run 2.7 µm and 1.55 µm laser lines used for medical surgery and IR countermeasures. In a nanoparticle synthesis lab, ErF3 ends up in NaYF4:Yb,Er upconversion nanocrystals, which you can image by exciting at 980 nm and watching them light up green under a microscope — the basis for deep-tissue biological imaging that avoids tissue autofluorescence.
Common Uses
- Dopant in ZBLAN fluoride-glass fiber amplifiers for C-band and L-band DWDM telecom
- Activator in NaYF4:Yb,Er upconversion nanocrystals for deep-tissue bioimaging
- Gain-medium dopant in 2.7 µm and 1.55 µm mid-infrared fiber lasers
- Calcium metallothermic reduction feedstock for Er metal production
- Anti-counterfeiting upconversion phosphor in currency and pharmaceutical packaging
- Optical thin-film material for IR window coatings
- Reference compound for Er3+ luminescence quantum yield measurements
- Co-dopant in scintillator and storage-phosphor crystal growth
Safety Information
GHS H315/H319 (skin and eye irritation, Category 2/2A). Low acute toxicity (LD50 > 5 g/kg orally in rat) — the lattice is stable enough not to release significant fluoride at physiological pH. Acid digestion (HNO3 or HCl) generates HF, so any sample-prep procedure for ICP-MS analysis needs hood work, calcium gluconate gel on hand, and PTFE labware. Airborne dust is controlled as a soluble fluoride, on fluoride content rather than on the erbium. Long-term inhalation of rare-earth fluoride dust has been associated with pulmonary fibrosis in refinery cohorts.
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.