Product Short Description: LITHIUM FLOURIDE 98% Product Description: LiF is therefore used in specialized optics for the vacuum ultraviolet spectrum, (See also magnesium fluoride). Lithium fluoride is used also as a diffracting crystal in X-ray spectrometry.Lithium fluoride is most widely used as a flux in the production of ceramics, such as enamels, glasses and glazes. Similarly it is also used in brazing and welding fluxes and molten salt chemistry in metallurgy.