It can be produced by reducing californium triiodide with hydrogen in a quartz thin tube at 570 °C:[2]
2CfI3 + H2 → 2CfI2 + 2HI
Physical properties
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 CdCl 2-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 CdI 2-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).[4]