2663. Cuprous Mercuric Iodide

Nomenclature

CAS number: 13876-85-2
(T-4)-Dicopper(1+) tetraiodomercurate(2-); copper(I) iodomercurate(II); cuprous tetraiodomercurate(II); mercuric cuprous iodide.
Cu2HgI4; mol wt 835.30.
Cu 15.22%, Hg 24.01%, I 60.77%.

Description and references

Superionic, thermochromic material; exists in two temperature dependent forms; a structurally ordered low temperature β-form and the more random high temperature α-form. Prepn and structural studies: J. A. A. Ketelaar, Z. Kristallogr. 80, 190 (1931). Prepn and phase diagram: M. Friesel et al., Phys. Scr. 35, 34 (1987); J. N"olting et al., Ber. Bunsen-Ges. Phys. Chem. 93, 1335 (1989). Optical properties: H.-R. C. Jaw et al., Inorg. Chem. 26, 1387 (1987). Crystal structure and phase transition studies: L. Eriksson et al., Z. Kristallogr. 197, 235 (1991). High temperature powder neutron diffraction studies: S. Hull, D. A. Keen, J. Phys. Condens. Matter 13, 5597 (2001). Use in holography: J. M. Yang, D. W. Sweeney, Appl. Opt. 18, 2398 (1979); in titrimetric applications: O. E. S. Godinho et al., Anal. Lett. 17, 135 (1984).

Properties

Deep-red, thermochromic cryst powder. Changes from scarlet to chocolate-brown at 67°. Poisonous. Practically insol in water, alcohol.

Use

For detecting overheating of machine bearings, etc. In pigments to prepare paints. Recording material for infrared holograms. Analytical reagent in titrimetric determn.