The invention discloses a method for preparing
rare earth fluoride by using fluorinated
ionic liquid. The
rare earth fluoride is represented by a
chemical formula REF3, wherein RE is selected from at least one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y and Sc. A fluorinated
ionic liquid and
rare earth oxides are used as raw materials, the rare earth oxides are directly converted into rare earth
fluoride through a solvothermal method, and the reaction can be carried out under a relatively low-temperature condition, so that a certain danger caused by
fluorine gas generated at a high temperature is avoided; and meanwhile, the preparation method of the rare earth fluoride provided by the invention is mild in reaction condition, and the rare earth fluoride can be obtained without adding any surfactant, catalyst or template, so that the purity and the yield of the rare earth fluoride are greatly improved. The
oxygen content of the rare earth fluoride prepared through the method is lower than 100 ppm, and the rare earth fluoride can be widely used for preparing rare earth fluoride single crystals, low-
oxygen metal gadolinium and fluorescent matrix materials.