RADIATION EFFECTS IN CERAMICS

Ceramics represent a large class of solids with a wide spectrum of app licability, whose structures range from simple to complex, whose bondi ng runs from highly ionic to almost entirely covalent and, in some cas es, partially metallic, and whose band structures yield wide-gap insul ators, narrow-gap semiconductors or even superconductors. These solids exhibit responses to irradiation which are more complex than those fo r metals. In ceramic materials, atomic displacements can be produced b y direct momentum transfer to often more than one distinguishable subl attice, and in some cases radiolytically by electronic excitations, an d result in point defects which are in general not simple. Radiation-i nduced defect interaction, accumulation and aggregation modes differ s ignificantly from those found in metals. Amorphization is a frequent o ption in response to high-density defect perturbation and is strongly related to structural topology. These fundamental responses to irradia tion result in significant changes to important applicable properties, such as strength, toughness, electrical and thermal conductivities, d ielectric response and optical behavior. The understanding of such phe nomena is less well-understood than the simple responses of metals but is being increasingly driven by critical applications in fusion energ y production, nuclear waste disposal and optical communications.