Electrolytic coloration of air-grown sodium fluoride crystals

Air-grown sodium fluoride crystals were colored electrolytically by using a pointed cathode at various temperatures and electric field strengths, which should mainly benefit appropriate coloration temperatures and electric field strengths. image, F, M, N1, N2 color centers and O2−–F+ complexes were produced in the colored crystals. Current–time curves for the electrolytic colorations were given, and activation energy for the V color center migration was determined. The formation of the color centers was explained.