Yttrium fluoride

Yttrium fluoride (CAS 13709-49-4), systematically yttrium(III) fluoride or yttrium trifluoride (YF₃), is an anhydrous rare earth compound.

Where is Yttrium fluoride used?

• Electronics and semiconductors: source material for plasma-chamber protective coatings, where YF₃ and yttrium oxyfluoride (YOF) layers resist halogen-based plasma etch chemistries
• Optical coatings: evaporation source for thin-film low-refractive-index anti-reflection layers, a ThF₄-free alternative with comparable refractive index and superior handling safety
• Sputtering targets made from high-purity YF₃ powder support physical vapour deposition (PVD) process lines
• Photonics and lasers: fluoride precursor for yttrium lithium fluoride (YLF) laser crystals, fluoride glass and fibre for infrared optical systems
• Metals and mining: intermediate in metallothermic reduction of yttrium metal via calcium reduction and in Mg–Y master alloys that refine grain structure and improve elevated-temperature mechanical properties in magnesium alloy systems for aerospace and defence components
• Its low phonon energy makes fluoride hosts grown from YF₃ feedstock attractive for mid-IR transmission.

Good to know: Registered under REACH for commercial supply into the European market. Oxygen impurity is controlled to ≤ 0.1 % for optical-coating applications to preserve low-absorption characteristics in the UV–VIS–NIR window.

Commercial specifications

• Density 4.01 g/cm³; melting point 1,387 °C; refractive index approximately 1.5
• Purity grades 2N to 5N on a rare earth oxide basis, typically YF₃/TREO ≥ 99 % up to ≥ 99.99 %; TREO generally above 80 %
• Forms: milled powder with median particle size (d₅₀) 1–10 µm; thermal-spray granules 10–60 µm; evaporation granules 0.2–5 mm
• Packaging: 1 kg and 5 kg containers for research and process-qualification lots; 25 kg drums for production-scale supply