GeSe2

GeSe2, or germanium diselenide, is a binary inorganic compound consisting of germanium and selenium in a 1:2 ratio. It belongs to the family of chalcogenide materials and is studied in both crystalline and amorphous (glassy) forms. In the crystalline phase, germanium centers are fourfold coordinated by selenium to form a covalent network of GeSe4 tetrahedra linked by Se atoms; the amorphous form retains a similar network with varying connectivity.

GeSe2 is typically prepared by direct combination of elemental germanium and selenium at elevated temperature, followed by controlled cooling to obtain a crystalline solid, or rapid quenching to yield a glass. Thin films can be deposited by chemical vapor deposition, sputtering, or other vapor-phase techniques.

Properties of GeSe2 include important optical and electronic characteristics typical of chalcogenide glasses: it generally exhibits a wide band gap relative to many semiconductors, high refractive index, and good infrared transparency in bulk and glassy forms. It is relatively brittle as a solid and is chemically reactive with oxidants at elevated temperatures.

Applications focus on chalcogenide glasses and thin films as infrared optical materials and nonlinear optical media. GeSe2-based glasses are used in infrared optics, waveguides, and optoelectronic device research; the material also serves as a model system for studying structure–property relationships in chalcogenide networks and glass formation.

GeSe2 is often studied alongside related chalcogenides such as GeSe and Ge-S–Se systems, contributing to broader understanding of germanium chalcogenides.