Electrical fluoride glasses

Use Ceramic flux, carbon brushes for electrical equipment, glass making, manufacture of other fluorides, crystals for spectroscopy, electronics, dry-film lubricants. 

Figure 7.18. Master plots for electrical and mechanical relaxation in an anionconducting (F ) heavy-metal fluoride glass (After Angel1, 1990).

Grind finely pure laboratory grade, anhydrous potassium fluoride, and heat it in an electrically heated oven at 180-210° store in a desiccator. Before use, dry the powdered salt at 180° for 3 hours and grind again in a warm (ca. 50°) glass mortar. 

Cadmium Fluoride. Elemental fluorine reacts with cadmium metal as well as the oxide, sulfide, and chloride to give CdF2 [7790-79-6]. Alternatively, treatment of CdCO with 40% HF yields a solution of CdF2, which may be evaporated to recover efflorescent crystals of the dihydrate. CdF2 has been used in phosphors, glass manufacture, nuclear reactor controls, and electric bmshes and in 1991 sold as a pure electronic grade (99.99%) at l/g. 

Since hydrogen ions are six to twelve times more mobile than other cations, there will be a delay between loss of hydrogen ions from solution and migration of glass cations into the aqueous phase. Presumably, this electrical imbalance results in an electric field which acts as a driving force for the migration of cations. Aluminium and fluoride are almost certainly transported as cationic aluminofluoride complexes, AIF and AIFJ, mentioned above. 

---