Glass-metal particulate composites

Abstract

Oxide glasses containing ultrafine metal particles have interesting physical properties and have been widely used in practical systems. The various preparational techniques developed so far for making these materials are discussed. Electrical conduction in these composites is controlled by electron tunnelling between the metal islands. At high electric fields certain glasses containing bismuth granules show a memory switching effect. The latter has been explained by a particle stretching model. Optical absorption characteristics of these composites can be explained on the basis of various effective medium theories developed so far for inhomogeneous materials. Glasses containing ferromagnetic metal grains show a superparamagnetic behaviour with a transition temperature below 300 K. Improvement in the mechanical properties of glasses can be achieved by incorporating metal particles of suitable characteristics within them. In this paper the present state of understanding of all these properties is reviewed.