Fluoride glasses: fluorophosphates

Some zinc phosphate glasses have low transition temperatures and excellent water resistance [19], Fluorophosphate glasses based on AlfPOjlj and LiF possess special optical properties in addition to having good water resistance. Glasses of this kind, based on combinations of other cation metaphosphates and fluorides, have been patented [20]. 

Dedicated benchtop NMR analyzers for a variety of applications are available. These include an analyzer to determine fluoride in toothpaste quantitatively, such as the MQC from Oxford Instruments, a 23 MHz benchtop NMR, and another to determine water droplet size distribution in oil/water emulsions. Fluoride is often added to toothpaste as sodium fluoride or sodium mono-fluorophosphate to prevent tooth decay. The fluorine analyzer can determine fluorine at the level of a few hundred ppm. Toothpaste is squeezed into a glass sample tube and the quantitative determination of fluorine takes less than 1 min. The NMR method uses no solvents or reagents and is independent of the sample color and clarity, unlike the colorimetric methods and other instrumental methods such as ion chromatography (IC) that are used for this purpose. In the water droplet size distribution analyzer, droplets as small as 0.25 pm can be measured. The shelf life and palatability of products such as margarine, mayonnaise, salad dressings, and soft cheese depend on the size of... 

Within a few years these very first results were followed by laser effects in other R ions such as Pr +, Ho +, Er +, Tm +, Yb +, Dy +. In particular Er laser emission at 1.5 pm was obtained in silica glass (Snitzer and Woodcock 1965), and studied in phosphate, beryllium fluoride, fluorophosphate glasses (Auzel 1966a, 1968). All these pioneer results have already been reviewed in several books (for instance, Di Bartolo 1968, Roess 1969, Weber 1979 in volume 4 of this Handbook Kaminskii 1981, Reisfeld and Jorgensen 1977). 

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