USA As Represented by Secretary of the Navy

Oscar Imber

Irwin Schneider

Philipp H Klein

William C Collins

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.sup.++ and between 0 and 10 ppmA Ca.sup.++ ; between 0 and 50 ppmA of non-fluorine halide anions; between 0 and 10 ppmA of SiF.sub.6.sup.= ; 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.

Growing community of inventors

Wheaton, MD, United States of America

Oscar Imber