Europium(II) iodide
Europium iodide is the iodide salt of divalent europium cation.
Preparation
Europium iodide can be prepared in a handful of ways, including:Reduction of europium(III) iodide with hydrogen gas at 350 °C:
Thermal decomposition of europium(III) iodide at 200 °C:
Reaction of europium with mercury(II) iodide:
Reaction of europium with ammonium iodide:
Structure
Europium iodide has several polymorphs. It adopts a monoclinic crystal structure in space group P 21/c.It also adopts an orthorhombic polymorph in space group Pbca. This form is isostructural with strontium iodide.
A third polymorph of europium iodide is formed if it is prepared from europium and ammonium iodide at low temperatures in liquid ammonia. This low-temperature phase is orthorhombic and in space group Pnma. This is the same structure as modification IV of strontium iodide.