Metal Halide Induced Chemical Disorder in Chalcogenide Glasses

Chalcogenide glasses containing light alkali and Group 11 (Cu, Ag) halides MY (Y = Cl, Br, I) exhibit high ionic conductivity while their heavy alkali counterparts show promising properties for optical applications. The structural role of metal halides in chalcogenide glass networks remains either essentially unknown (alkali halides) or controversial (CuY, AgY). Recently, we have found unexpected role of silver halides as unconventional modifiers in AgY-As2S3 glasses in a drastic contrast to a common point of view considering AgY to be chemically inert in the glass network. Both the chemical interaction of silver with sulfur species was found, and As-As homopolar bonds in stoichiometric glasses. The extension of these findings to CuY and alkali halide glasses will help understanding the structural features of practically important systems.