MODIFIED PURIFICATION OF MERCURIC IODIDE FOR CRYSTAL-GROWTH

The standard procedure used in our laboratory to purify commercially available mercuric iodide (HgI//2) consists of a sequence of steps: (1) repeated sublimation under continuous evacuation, followed by (2) melting and recrystallization, and (3) a sublimation process in a closed tube. This paper describes a modification of the standard purification sequence by adding recrystallization of the HgI//2 in hydrochloric acid. Leaching cation impurities out of HgI//2 powder with hydrochloric acid has been practised before by Zaletin et al. Our objective for the hydrochloric acid treatment was to remove nitrates and hydrocarbons which were interfering with the vapor transport during crystal growth. Results of the procedure are presented in terms of total carbon and selected ion content of the treated and untreated material.