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 hygroscopic fluoride, it reacts with water vapour and generates gaseous HF. The niobium fluoride processing (NFP) consists of storing a wet or oxide starting material in a closed enclosure containing NbF5. The temperature is below 80 degrees C and the time may reach several weeks. The NFP has been successfully used for the synthesis of crystalline fluorides 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.