Californium(II) iodide is a binary inorganic compound of californium and iodine with the formula CfI2.
[1] It can be produced by reducing californium triiodide with hydrogen in a quartz thin tube at 570 °C:[2] The compound forms a dark purple solid.
At slightly higher temperatures, it melts and reacts with the silica in the thin tube, producing CfOI.
[citation needed] Californium diiodide has two crystal structures, one is CdCl2-type crystal structure, stable at room temperature, with lattice parameters a = 743.4 ± 1.1 pm and α = 35.83 ± 0.07°; the other is metastable, of CdI2-type with lattice parameters a = 455.7 ± 0.4 pm and c = 699.2 ± 0.6 pm.
[3] Californium diiodide has an absorption band in the wavelength range from 300 to 1100 nm, which proves the existence of Cf(II).