Yttrium iodide was prepared by reacting yttrium metal turnings with ammonium iodide. The resulting salt was distilled into a melting point assembly and t he melting point and vapor pressure were determined by conventional techniques . Little decomposition of the iodide on a hot surface was observed under conditions that gave 100% decomposition of zirconium iodide.
Dennison, D. H.; Spedding, F. H.; and Daane, A. H., "The determination of the melting point, the vapor pressure, and the decomposition temperature of yttrium tri-iodide" (1959). Ames Laboratory Technical Reports. 9.