Photodichroic Crystals and Preparation Thereof.
DEPARTMENT OF THE NAVY WASHINGTON D C
Pagination or Media Count:
Patent on the improvement of the electrolytic and additive methods of coloring alkali fluoride crystals comprising the step of selecting an alkali fluoride crystal having the impurities of between 0 and 5 ppmA of OH between 0 and 50 ppmA of one or more alkaline earth cations, of which between 0 and 10 ppmA Mg and between 0 and 10 ppmA Ca between 0 and 50 ppmA of nonfluorine halide anions between 0 and 10 ppmA of SiF6, between 0 and 30 ppmA of other ions and the method of preparing these crystals which comprises converting the alkali fluoride to alkali hydrofluoride, crystallizing and vacuum drying the alkali hydrofluoride crystals, regenerating the alkali fluoride by expelling hydrogen fluoride, and crystallizing the alkali fluoride. Author