Selenium Sputtering Targets (Se)

Selenium forms several allotropes that interconvert with temperature changes, depending somewhat on the rate of temperature change. While in chemical reactions, selenium is usually an amorphous, brick-red powder. If rapidly melted, it forms the black, vitreous form, usually sold commercially as beads. The black selenium structure is irregular and complex and consists of polymeric rings with up to 1000 atoms per ring. Black Se is a brittle, lustrous solid that is slightly soluble in CS2. Upon heating, it softens at 50 ℃ and converts to gray selenium at 180  ℃; the presence of halogens and amin reduces the transformation temperature.