Preparation method of Terbium Fluoride TbF3
Terbium Fluoride TbF3, chemical formula: TbF₃, colorless hexagonal crystal, density 7.2, melting point 1172℃, boiling point 2280℃. Stable under normal temperature and pressure. Insoluble in cold water, hot water and dilute acid. Mainly used for the preparation of metal terbium, magnetostrictive materials.
The hydrofluoric acid is added to the terbium salt aqueous solution, or the hydrated Terbium Fluoride TbF3 is prepared by the reaction of terbium hydroxide and hydrofluoric acid, and then the crystal water is removed by heating in a vacuum.
The concentration of hydrofluoric acid is generally 40%~48%, and its consumption is 110%~120% of the theoretical amount. The precipitate of Terbium Fluoride TbF3 precipitated from the aqueous solution must be thoroughly washed with water, and the water washing is carried out by the pouring method. The filtered precipitate was dried at 100~150°C to remove adsorbed water. A fluoride containing only water of crystallization is obtained. In order to avoid high temperature hydrolysis during dehydration to generate oxyfluoride TbOF, the dehydration process needs to be heated in vacuum. The vacuum degree should be higher than 0.133Pa, and the dehydration temperature should not be lower than 300℃.
Another dehydration method is to dehydrate the hydrated Terbium Fluoride TbF3 in a stream of dry hydrogen fluoride, and the final dehydration temperature is 600-650 °C. This dehydration method under the protection of hydrogen fluoride atmosphere can further fluoride the hydrated Terbium Fluoride TbF3 during the dehydration process, which can ensure the quality of the product. Since the hydrofluoric acid precipitation is carried out in an aqueous solution, a plastic container is generally used, and the material of the dehydration equipment must be resistant to high temperature corrosion, and a nickel-based alloy or pure nickel is generally used as the lining material.