Yttrium oxyfluoride

Yttrium oxyfluoride is an inorganic chemical compound with the formula YOF. Under normal conditions, the compound is a colorless solid.

Synthesis
Yttrium oxyfluoride may be formed in the decomposition of crystalline hydrate of yttrium fluoride upon heating to 900 °C in a vacuum:
 * $$\mathsf{2YF_3\cdot 1/2H_2O \ \xrightarrow{\tau, 900^oC}\ YOF + YF_3 + 2HF }$$

Yttrium oxyfluoride can also be made by hydrolysis of yttrium fluoride with superheated steam at 800 °C:
 * $$\mathsf{2YF_3 + H_2O \ \xrightarrow{800^oC}\ YOF + 2HF }$$

Physical properties
Yttrium oxyfluoride forms colorless crystals of tetragonal crystal system; its cell parameters are: a = 0.3910 nm, c = 0.5431 nm. According to hexagonal crystal family, the cell parameters are: a = 0.38727 nm, c = 1.897 nm, Z = 6.

Applications
Stable yttrium oxyfluoride material is used for inner walls of plasma process equipment.