chalcogenide

Chalcogenide is a term used for compounds that contain one or more chalcogen elements, the elements of group 16 in the periodic table: oxygen, sulfur, selenium, tellurium, and polonium. In many contexts, chalcogenides are understood to be sulfides, selenides, tellurides, or mixed chalcogen compounds combined with metals or metalloids. Oxides are sometimes treated separately, but oxygen can be considered a chalcogen in broader discussions of chalcogen chemistry.

Chalcogenides display a wide range of bonding and structures. Binary chalcogenides such as ZnS, CdS, PbS, ZnSe, and PbSe are well studied, and layered transition metal dichalcogenides like MoS2 and WS2 exhibit two-dimensional properties relevant to electronics and catalysis. Mixed chalcogenides, including sulfide-selenide and telluride-sulfide systems, allow tuning of electronic and optical properties, including band gaps, conductivity, and refractive indices. Chalcogenides can form ionic, covalent, or mixed bonding, and many exhibit interesting semiconducting or optoelectronic behavior.

Applications span several fields. In electronics and optics, chalcogenides are used in semiconductors and photodetectors, as well as in infrared optics through Se- and S-based chalcogenide glasses. Phase-change materials such as Ge2Sb2Te5 rely on telluride chemistry for memory applications. In energy storage and catalysis, sulfide-based systems serve as solid electrolytes or catalytic materials. Chalcogenide minerals are important metal ores, hosting elements like copper, lead, and zinc. Some chalcogenides pose toxicity or environmental hazards and require careful handling.