Beryllium double fluorides

The double fluoride, ammonium hexafluorovanadate ((NH4)3VF6), forms from the oxide at 210 to 250 °C, but decomposes at 600 to 700 °C to yield pure vanadium fluoride. Examples of metal fluorides obtainable through the double fluoride route include uranium tetrafluoride, beryllium difluoride and the rare earth fluorides ... 

Fluorides are nonhygroscopic, and their melting points are higher than those of the corresponding chlorides. Besides, the fluoride reduction reactions are considerably more exothermic. The prime examples of the use of fluorides as intermediates are the reduction of uranium tetrafluoride by calcium or magnesium the reduction of rare earth fluorides by calcium, reduction of beryllium fluoride by magnesium and the reduction of potassium tantalum double fluoride by sodium. 

Conditions like those described in Equation 9 exist also in the reduction of beryllium fluoride or its double fluoride (90) with sodium, according to ... 

Determined specific heat as 4453 from a 94 per cent, metal made by action of Na on BeClj. Speaks of the possibility of electrolyzing double fluoride of K and Be, but says material is very impure from fluorine attacking containing vessel. Gives many properties of Be and BeO not consistent with those of later investigators. Main study was evidently on specific Tieat, which being obtained at low temperatures, lead him to the belief in trivalent beryllium. 

The impure hydroxide obtained above is purified by converting to a double salt, ammonium beryllium fluoride, which subsequently, on thermal decomposition, gives beryllium fluoride. The latter is heated with magnesium metal... 

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