Gadolinium(III) fluoride

Gadolinium(III) fluoride is an inorganic compound with a chemical formula GdF3.

Preparation
Gadolinium(III) fluoride can be prepared by heating gadolinium oxide and ammonium bifluoride. The reaction involves two steps:
 * Gd2O3 + 6 NH4HF2 → 2 NH4GdF4 + 4 NH4F + 3 H2O
 * NH4GdF4 → GdF3 + NH3 + HF

Alternatively, reacting gadolinium chloride with hydrofluoric acid and adding hot water produces GdF3·xH2O (x＝0.53). Anhydrous gadolinium(III) fluoride can then be produced by heating the hydrate with ammonium bifluoride; without the bifluoride, GdOF is formed instead.
 * GdCl3 + 3 HF + x H2O → GdF3·xH2O + 3 HCl

Properties
Gadolinium(III) fluoride is a white solid that is insoluble in water. It has an orthorhombic crystal structure with the space group Pnma (space group no. 62).

Uses
Gadolinium(III) fluoride is used to produce fluoride glasses.