The way from today's materials to new kinds of amorphous solids: Nano-glasses

Abstract

This review discusses the preparation, the atomic structure and the properties of new kinds of nanometer structured solids that consist either totally or partially of non-crystalline components. In the first part solid materials will be considered that are assembled of nanometer-sized glassy regions connected by glass-glass interfaces (called nano-glasses). The atomic and electronic structure of these nano-glasses (and hence all their structure dependent properties) differ from the ones of today's glasses (same chemical compositions) without glass-glass interfaces. In fact, nano-glasses may open the door to new technologies because they permit - for the first time - to produce non-crystalline materials with controllable defect microstructures and/or chemical microstructures resulting in new kinds of non-crystalline materials with new properties. The control of properties by varying the defect/chemical microstructure was limited so far to crystalline materials and it is the main reason why most present technologies utilize crystalline materials. In the second part materials will be discussed with nanometer-sized gas or liquid filled pores (nano-porous materials). Their properties are controlled by the high density (~1015 mm-3) of solid/liquid or solid/gas interfaces which can be tuned reversibly e.g. by applying an external voltage between an aqueous electrolyte in the pores and a nano-porous material. Due to the high density of these interfaces, the entire nano-porous material actslike a structurally homogeneous body andbecomes a solid of macroscopic dimensions with tunable mechanical, electric, magnetic etc. properties. © Printed in India.