PbF2 LEAD FLUORIDE

PbF2 LEAD FLUORIDE 797.7308 -6.5142E+04 -2.6816E+02 8.0837E-02... 

PbF2 LEAD FLUORIDE 54.940 6.4425E-02 -9.8385E-13 1.4615E-15 -7.9884E-19 298 613 solid... 

Lead Fluoride. Lead difluoride plumbous fluoride. FjPb mol wt 245.21. F 15.50%, Pb 84.50%. PbF2, Prepd by treating lead carbonate or hydroxide with hydrogen fluoride and evaporating the soln by mixing solns of potassium fluoride and lead acetate by precipitation From the soln of a lead salt by HF by the action of fluorine on lead Ruff, Die Chemie des Fluors (Springer, Berlin, 1920)... 

Interest in solids with highly mobile ionic species is not new. In 1839, Michael Faraday reported measurements on several materials including lead fluoride (PbF2) that showed an unusual increase in the electrical conductivity at elevated temperatures, contrary to that found in normal metals. This finding was a surprising discovery, since most simple salts are not good conductors of electricity. 

Although Faraday discovered the unusual electrical properties of lead fluoride, he did not explain his observations. It is now known that the high electrical conductivity of PbF2 is due to the motion of F ions, not electrons. At 500-700°C, fluoride ions diffuse rapidly through the PbF2 lattice. PbF2 was the first example of a solid with high ionic conductivity. 

PbF2 is readily prepared by the action of hydrogen fluoride on lead hydroxide, lead carbonate, or a-lead oxide. It can also be obtained by precipitation from lead nitrate or lead acetate solutions using potassium fluoride, ammonium fluoride, or ammonium bifluoride. 

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