alphaHgI2

Alpha mercury iodide, or alpha-HgI2, is the alpha polymorph of mercuric iodide, HgI2. Mercuric iodide is an inorganic compound that consists of mercury(II) cations and iodide anions in a 1:2 ratio. The alpha form is one of two crystalline polymorphs known for HgI2, the other being beta-HgI2. The two forms differ in crystal structure and physical properties, and they can interconvert under changes in temperature or crystallization conditions, with the beta form often more stable at ambient conditions.

In general, HgI2 is a pale yellow to orange-yellow crystalline solid with very low solubility in water. It is sensitive to heat and can decompose upon heating, and its exact melting behavior can depend on the crystal form. The alpha and beta polymorphs exhibit different lattice arrangements, which influence aspects such as crystal growth, defect density, and charge transport.

Alpha-HgI2 has been studied for its potential use in solid-state radiation detectors because mercuric iodide materials combine a high effective atomic number with a wide band gap, enabling photoconductive and detector-type applications. Research has focused on optimizing crystal quality, purity, and film deposition to enhance charge collection and detection efficiency in X-ray and gamma-ray sensing.

Safety considerations are important: mercuric iodide is a mercury compound and is toxic. Handling should be conducted with appropriate containment, ventilation, and waste disposal in accordance with applicable regulations.

See also: mercuric iodide, HgI2, polymorphism, radiation detector materials.