Holmium Iodide Hydrates: Synthesis and Properties

Heterogeneous equilibria in the Ho2O3-HI-H2O and HoI3-HI-H2O ternary aqueous systems at 25°C are studied by the isothermal method. The crystallization fields are established, and the compounds HoI3 · 9H2O and Ho2I(OH)5 · 2H2O are isolated. The compounds are characterized by chemical, crystal-optical, and thermogravimetric analyses and X-ray diffraction. As is shown by thermal analysis in air, stable intermediate phases of compositions HoOI · 3Ho2O3 and HoOI · Ho2O3 exist in the region from 370 to 600°C.