Metallic nanoparticles (Cu, Ag, Au) in chalcogenide and oxide glassy matrices: comparative assessment in terms of chemical bonding

Abstract

Principal difference in origin of high-order optical non-linearities caused by metallic nanoparticles such as Cu, Ag, and Au embedded destructively in oxide- and chalcogenide-type glassy matrices has been analyzed from the viewpoint of semiempirical chemical bond approach. The numerical criterion has been introduced to describe this difference in terms of the mean molar bond energies character for chemical interaction between unfettered components of the destructed host glassy matrix and embedded guest atoms. It has been shown that “soft” covalent-bonded networks of chalcogenide glasses of As/Ge–S/Se systems differ essentially from glass-forming oxides like silica by the impossibility to accommodate agglomerates of metallic nanoparticles. In contrast, such nanostructured entities can be well stabilized in Cu-, Ag-, or Au- embedded oxide glasses in full accordance with numerous experimental evidences. Recent unsubstantiated speculations trying to ascribe this ability to fully-saturated covalent matrices of chalcogenide glasses like As₂S₃ are analyzed and criticized as misleading and inconclusive.