ROOM-TEMPERATURE SYNTHESIS OF FLUORIDE GLASSES

A new fluorination process based on soft chemistry has been developed. It uses the chemical properties of niobium pentafluoride. As a very h ygroscopic fluoride, it reacts with water vapour and generates gaseous HF. The niobium fluoride processing (NFP) consists of storing a wet o r oxide starting material in a closed enclosure containing NbF5. The t emperature is below 80 degrees C and the time may reach several weeks. The NFP has been successfully used for the synthesis of crystalline f luorides such as LiF, NaHF2, CaF2, BaHF2. Powdered fluoride glass was prepared at room temperature for 20 days from a wet oxide gel with the suitable cationic composition. Vitreous materials were characterized by differential scanning calorimetry and X-ray diffraction.