Changing Face of the Chameleon

by A. Lindsay Greer & Neil Mathur Nature, 27 Oct 2005 The chalcogens -- the elements in group VI of the periodic table, particularly sulphur (S), selenium (Se) and tellurium (Te) -- react with more electropositive elements, such as silver, to form chalcogenides. These are chameleon compounds: they can be crystalline or amorphous, metallic or semiconducting, and conductors of ions or electrons. Already important in optical storage discs and fibres, they are now being proposed as the basis for solid-state memory technologies. Two recent conferences have demonstrated that devices using chalcogenides hinge on thermal and dynamic phenomena involving electronic, atomic and ionic processes. The links between these phenomena are not fully established, so unsuspected technological opportunities may well lie in store. Read more